Electrical System Troubleshooting

Last updated: May 20, 2002

Starting Problems

Date: Tue, 4 Jun 2002 00:41:51 -0700
From: "Nathan Kwok" (natek@ucla.edu)
Subject: re: (rx7) [3] Warm starts

I highly doubt your motor is going bad. I'm not sure who told you hard warm starts are a symptom of the motor "going bad", but most problems tend to manifest themselves when the car is cold, not warm, because that is when sealing is the worst. A compression check will reveal problems and it never hurts to know however. If by some chance you have an auto, take a look at this: Good luck. -Nathan Kwok '93VR

Applicable Models: 1993 RX-7 A/T
Subject: NO START AFTER HEAT SOAK

APPLICABLE MODELS/VINS
- ----------------------
1993 RX-7

Automatic transmission vehicles with a VIN of JM1FD***P0200001 through
JM1FD3***P0210498.

DESCRIPTION
- -----------
Hard restart after running the vehicle at high speeds on hot days. Vehicle
restarts easily after engine compartment cools down.
This hard start condition is caused when heat from the engine increases the
electrical resistance in the starter wire. This decreases the amount of
current received at the "S" terminal on the starter.

To correct this problem, the starter harness length has been changed and the
amount of current applied to the "S" terminal during starting increased.

REPAIR PROCEDURE
- ----------------
If the condition exists, install the countermeasure starter wire harness.
1. Disconnect the vehicle battery.
2. Raise the vehicle on a hoist or raise the front end with ramps.
3. Disconnect the connectors at the starter.

[Picture showing where to disconnect the harness]

4. Connect countermeasure harness FDY1 67 SH0 as shown.

[Picture showing where the new harness fits in]

5. Tape off the OEM starter solenoid wire. Secure countermeasure harness
with 4 tie-wraps E018 67C92. Confirm there is no interference between
the brake and fuel lines.

[Picture showing where to install the tie-wraps]

PARTS INFORMATION
- -----------------
PART NUMBER: FDY1 67 SH0
DESCRIPTION: Starter Wire Harness
QTY: 1

PART NUMBER: E018 67 C92
DESCRIPTION: Tie-Wrap
QTY: 4

________________

Date: Sun, 19 Mar 2000 07:40:45 -0500
From: Ian Hobbs (ianhobbs@home.com)

I have had a couple of different 2nd gens that I had starting problems with (both had different problems) so am familiar with your frustration. I am not an expert as many on this list are but I will give you my two cents.

First option, it could still be flooded. Just changing the plugs never deflooded mine. After getting tired of paying the towing fees I began experimenting and found the most effective way to re start was pulling the egi fuse and turning it over for 10-15 seconds, then putting the fuse back in and turning it over again. Try 2 or 3 times. If it was really flooded I had to do the above, then take the plugs out and dry them, then do the above again. Doing the above as soon as it flooded avoids having to take the plugs out. I eventually had a fuel cut switch installed so I did not have to get out, pop the hood and pull the fuse every time.

Second option, spark problem. You have changed the plugs and wires so that rules those out but you could have a coil problem. Put a timimg light on the wires and check that you are getting a spark from each wire. Check your battery and make sure it is up to strength. All the cranking in trying to get it started plays hell on the battery.

Third option would normally be fuel but it sounds like you have diagnosed this one fairly well. You mentioned that it had sat ove the winter, did you put a fuel stablizer in the gas tank??? Bad fuel could be a problem. You could test this by disconnecting the fuel feed from the tank and running a feed from an alternate source. You can get kits for doing this that are usually used for running injector/cylinder cleaning fluids through the engine.

Last option is the painfull one, you have an engine problem and are not getting compression. You can test this by pulling the plugs and using a compression tester. Look for consistency across the numbers between the chambers. If something is wrong i.e. an apex seal is shot/siezed you will normally see a big difference on one or two of the numbers. I store my cars in the winter but always start them every two weeks. Rotary engines do not sit well. Your options here are limited. I have seen some notes with regards to putting about a quarter cup of automatic transmission fluid in each cylinder to try to break down any carbon deposits/help with compression but have never tried this and would seek better advise than me before trying this.

Side note: If option 1 solves the problem and flooding is the issue you likely have 1 or more leaky injectors (common problem). If I understand this correctly their are two sets of injectors, primary and secondary. You can have the primary ones taken out and cleaned for a minimal charge which may solve the problem. Yu can also buy a little cross connector Mazdatrix that equalizes the fuel pressure in the rail which may help. If it is the secondary injectors either be prepared to spend big bucks or live with the fuel cut switch which is what I did on one of my 7's. On my other car it was a coil problem.

__________________

David Lane has written some excellent posts on starting problems. He has just (April 27, 1999) done a new write-up that might supercede his previous posts, but I am going to leave the older ones following the new one as well. --Steve

_______________

From: David Lane
Date: April 29, 1999

(Ed.'s note: this is indeed the revised article. --Steve)

BEFORE REPLACING YOUR STARTER MOTOR

Funny how cars always pick an inconvenient time to refuse to start. It's always just when you want to go somewhere.

How does it know?

We all understand about the rotary engine's classic flooding problem, and the solution is well documented elsewhere. Less well understood are the kind of problems which keep the car from cranking when you turn the key. All you get is a "click" from underneath the car, or perhaps the whole electrical system goes dead. One of my favorites is a really nasty grinding noise. Sometimes turning the key on and off a few times resolves the trouble--at least for awhile. Most people figure the starter motor is bad, and they replace it, only to discover that the trouble persists.

This article will help you trouble-shoot the electrical system which supports the starter motor. To help you make sense of it, I need to explain how the system works. Then, we can look at typical problem areas. These problems are most often associated with age, so it makes sense that they will show up with the earlier cars first. My own car is an '85 GSL-SE, but I understand that most RX-7s are the same (or at least similar).

The usual disclaimers apply: I am not a mechanic and I make no pretense about being an expert. However, I have experienced these problems on my car, and I want to share what I have learned.

At the end of the article I will give you some tricks to pep up your electrical system. I will also discuss the "grinding noise" problem in that section.

HOW IT WORKS

The starter is wired directly to the positive battery cable. Switching the starter motor on and off is accomplished by an electromagnet called the starter solenoid. Turning the key activates the solenoid, which does two things. First it slides a gear (connected to the starter motor) in place to mesh with a matching set of teeth around the engine flywheel. Then it moves a metal "contact plate" to complete the electrical circuit between the battery and the starter motor. This circuit requires clean electrical connections between the starter motor, both battery cables, and the engine. Hopefully, the starter motor starts to spin and the engine cranks. When the ignition key is released, the solenoid returns to its original position, breaking the electrical circuit, and removing the gear from the flywheel.

As usual, Mazda has their own way of naming things. The gear connected to the starter motor is called the "pinion" gear in the shop manual--probably to complement the "ring" gear which circles the flywheel. This is technically correct, but most mechanics refer to the gear on the starter motor as the "Bendix" gear, after the man who invented the engagement mechanism. In the shop manual, the solenoid is referred to variously as the "magnetic switch," or "magnet switch."

Troubleshooting the starting functions of the car is best done in three phases. First the battery and its connections must be checked. Then, depending on your particular problem, you can look at either the large battery cables that power the starter motor, or the smaller circuit which activates the solenoid.

THE BATTERY

Since it is central to the entire operation, the first thing to check is the battery. An ailing battery can give you differing symptoms depending on what is wrong with it. Slow cranking and dim lights, are typical of a battery that isn't up to snuff. A nearly dead battery can give you no cranking at all--just a clicking sound. You can also check the voltage meter on your car with the key on and the engine off. You should see around 12 volts. With the engine idling, but no electrical accessories on, you can see as high as 13.8 volts.

If you suspect that your battery is not doing its job, the best way to test it is "under load," simulating what the battery must do when the starter motor is cranking the engine. It takes a special machine to do that, so take the battery to a shop that specialized in batteries, or a good garage. Be advised that a battery can put out acceptable voltage at rest, and still not perform properly under load.

As part of checking the battery, pay particular attention to the terminals--the clamps that hold the cables to the battery posts. Strange as it may seem, it only takes a thin film of corrosion to block or severely inhibit flow of electricity to and from the battery.

Here is how to clean the terminals. Working with these connections can be hazardous if you are not careful, so heed the warnings as we go along.

  1. Remove both battery cables from the battery.

  2. Check to be sure the terminal is attached tightly to the cable itself.

  3. Use sandpaper or a commercial battery terminal cleaner to clean the terminals and the battery posts. You must see bright metal on the mating surfaces.

  4. Apply a thin coating of petroleum jelly to the battery post, or use a commercial corrosion inhibiting product.

  5. Replace the connectors on the battery posts.

The posts are slightly conical, so if the terminal is still loose after being tightened all the way, loosen it up again, spread it a little with a screwdriver, and maybe tap it lightly so that it clamps down more toward the base of the post.

PROBLEMS ASSOCIATED WITH BATTERY CABLES

When a battery cable goes bad, or a connection gets dirty, the effect is like an electrical traffic jam. The cables can't pass electricity fast enough to power the starter motor. Thus, when you turn the key, you hear a loud click from the solenoid, but there is not enough current to crank the engine.

The first task is to clean all connections associated with the cables. For safety, remove both cables at the battery before proceeding. Otherwise, you risk handling live cables, and the results can be a shower of sparks. Put the front of the car up on jack stands, or a ramp. Do not rely on a jack alone if you are under the car.

The first connection to check is the positive battery cable, where it terminates at the solenoid (located on the starter motor). The battery cable is the one on the left, covered with a rubber boot. Remove the cable and sand the connecting surface until it is bright. Replace the cable. While you are working in that area, you will notice a smaller wire terminating with a clip connector on the solenoid. This carries electricity from the ignition circuit, activating the solenoid when you turn the key. Might as well pull it off and clean up the post. You can also squeeze the female end attached to the wire if it no longer makes a tight connection.

While you are looking at the aft end of the solenoid, consider that the two large terminal posts are the ones connected by the metal plate when the solenoid is activated. If you look carefully, and have enough light, you will be able to see that the large post on the right has a wire attached to it which runs into the starter motor. Now let's go to the negative battery cable--the ground strap.

The ground strap is part of every electrical circuit in the car, so if it is internally corroded, or if the connections are dirty, everything will be affected to one extent or another. This includes lights, starting, and other things we don't usually think of, such as engine management computers and the various relays and small solenoids which serve switching and control functions. Some of these systems are mounted to the body. Others are mounted to the engine, so the ground strap is connected to both. As you can tell by the thickness of the wire going to the starter solenoid, powering the starter motor requires more electrical flow than any other electrical function, so any weakness in the ground strap is likely to show up there first.

The ground strap is connected to the engine. Mid-way down the cable is the connection to the body--typically part way down the driver's side shock tower. Remove the connections, sand until bright (including the mating surface in the shock tower), and replace. Third generations cars have another ground strap from the exhaust to the body. While a fault at this connection will not cause a starting problem, some owners have reported problems if this cable is not clean and solid.

Replace the connections at the battery, and try to start the car.

If this doesn't fix the problem, the next step is to test for internal corrosion in the cables. There is some possibility that the cables are corroded, but in the process of cleaning the terminals, you have caused enough internal friction to rub away some of the corrosion. In this case, the car might start, but exhibit the same problem at a later time. When the cables crud up internally, it is hidden underneath the insulation. Also, you can't test for corrosion with a volt meter because even a badly corroded cable will provide plenty of voltage to produce a reasonable reading. The best approach is to substitute a jumper cable (the ones you might use to jump start the car with a dead battery) for the cable you want to test. Here is how:

To test the ground strap, first disconnect the ground strap at the battery to expose the negative battery post. Connect one end of your jumper to a clean, unpainted place on the engine. Connect the other end to the negative battery post. Try to start the car. If you have no luck with that, remove the jumper cable from the engine and connect it to the body via an unpainted bolt or other piece of unpainted metal. Try to start the car again. If the car starts in either case, you need a new ground strap. You can get something close at a local parts store, or get the genuine Mazda part from Mazdatrix or your usual source of parts. It saves time to use a Mazda part because it has provisions for the body and engine connections. If the car doesn't respond to substituting a jumper cable for the ground strap, move on to the positive battery cable.

Testing the positive battery cable is a little more tricky. We want to avoid sparks, so the first thing to do is to remove the positive battery cable at the battery. Next, clamp one end of your jumper cable to the left hand post at the solenoid (where the stock cable is connected). Be very sure the clamp is ONLY touching the terminal post (including the stuff connected to it) and NOT anything else. Nothing on the body, nothing on the engine, nothing on the starter motor. Any contact with a ground such as those mentioned will result in a shower of sparks when you connect the jumper cable at the battery. To double check that you have a clean connection at the starter, bring the other end of the cable near the positive battery terminal and quickly brush it across. If you get no reaction, it is safe to clip it to the battery terminal. If you get sparks, recheck the connection at the solenoid. Once the jumper is in place, try to start the car. If the car starts, replace both battery cables (the negative cable, if not bad already, will go bad soon).

If the car still won't crank and you still get the click from the solenoid when you turn the key on, the problem is probably within the solenoid or the starter motor itself. You can check the solenoid with a test light or volt meter by clipping one connector to a ground on the engine or body, and the other to the right hand terminal on the solenoid (the one with the wire leading inside the starter motor). All connections of the battery cables are normal for this test. Turn the key to start. If the solenoid is good, you should see twelve volts or so on the meter. If you are using a test light, it should illuminate. If the solenoid seems good, it may be time to pull the starter motor and have it checked.

PROBLEMS ASSOCIATED WITH THE SOLENOID ACTIVATION CIRCUIT

If you turn the key and nothing happens--not even a loud "click" from under the car, and if you have properly checked the battery and cables, you may not be getting power to the solenoid. Here is how that circuit works--at least on a 1st generation car. Later models are probably similar in concept, but I have not researched it.

As usual, we start from the positive terminal of the battery. In addition to the thick wire which goes to the starter, there is another wire that supplies power for virtually everything else. This wire goes to the fuse box under the hood. First generation cars don't have a fuse box in the traditional sense, relying instead on what Mazda calls "fusible links." These are actually little U-shaped wires, loosely covered with cloth, and designed to burn through in the event a short circuit draws too much electricity through them. The box of fusible links is mounted to the front of the driver's side strut tower. Since later generations of RX-7s have a proper fuse box, they are less troublesome in this regard.

The fusible link marked "Main" is in the electrical path going to the dash board and ignition key. When you turn the key to "start" electricity is sent to the starter solenoid via the small clip-on connector located between the two large connecting terminals.

If turning the key to "start" results in the dash lights going out, you probably have a problem with the fusible links. Disconnect the positive battery terminal at the battery. I suggest removing the box of fusible links and cleaning all connections while you are there. Pay particular attention to the clip connections on the fusible links themselves. Remove, clean, and tighten the connection where the battery power comes in. Do not throw away a broken fusible link. You can get an in-line fuse holder from an auto parts store, but the size of the clip connector is not easy to find. You may have to solder the connector from the old fusible link on to the new fuse holder. A fuse holder is not a bad idea for the "main" circuit since fusible links (while not known to be particularly troublesome) are out in the open, and vulnerable to clumsy hands. Don't ask how I know .

If turning the key to "start" does not effect the dash warning lights, you will want to verify that the solenoid has power coming to it to activate the electromagnet. First, clean and tighten the clip-on connector at the solenoid. Next, check to see if it is getting power by putting a meter or circuit light between the wire and ground (an unpainted part on the engine or body). Turning the key to "start" should light the light, or register 12+ volts on the meter.

If the solenoid IS getting power, but not activating (no click) you may have a bad solenoid. The shop manual says you can check for continuity between the right hand post and the body of the solenoid. They illustrate this with the solenoid separated from the starter and off the car. At least remove the positive battery cable at the battery end. Remove all three cables from the solenoid terminals. Set your meter for resistance, or use a continuity checker. Check for continuity between the right hand post and the body of the solenoid. If you get no continuity, the solenoid is bad. Although the shop manual says to "replace the switch," I would not be surprised if you had to buy the whole starter/solenoid assembly. Just a hunch.

If the solenoid is NOT getting power, you may have a mechanical or electrical problem with the ignition switch itself.

HOW TO PEP UP YOUR ELECTRICAL SYSTEM

A respected RX-7 mechanic says that no car leaves his shop without the following simple modifications done to the electrical system. All are done with 8 or 10 gauge wire. You can secure the wire to the battery terminals using the terminal clamps, or you can get clamps which have provisions for extra wiring--as you might find with a complex auto sound system.

Run two new ground wires. One goes from the engine to the negative battery terminal. The other goes from a bolt or bare-spot on the chassis to the negative battery terminal. The additional ground paths will provide a little cushion for the stock wiring which is marginal when new. This has been known to solve low voltage problems at the cigarette lighter--the kind that gives you low voltage warnings on cell phones or Valentine One radar detectors. The V-1 detectors will show a false "laser alert" if you try to power it with low voltage.

Run one new wire between the alternator output (the wire secured by a nut) and the positive terminal of the battery. This parallels the stock wire and makes it "easier" for the alternator to recharge the battery. With both these modifications, you should see at least 13.8 volts at on your dashboard volt meter when at idle (but without other electrical loads).

THE GRINDING NOISE

At the beginning of this article, I spoke of a grinding noise you get sometimes when you try to start the car. Most often, you can just turn the key off and try again. Sometimes it takes several attempts to get the car to crank. Grinding occurs when the gear teeth of the starter motor and the flywheel ring gear fail to engage. The starter motor powers up and the gears grind against each other. Over time, this erodes the matching surfaces (bevels) on both gears, making the engagement process progressively more difficult. While there may be a mechanical reason for the problem, in many cases something is marginal in the electrical system. For instance, it may be that the solenoid is not getting enough power to solidly place the bendix gear in mesh with the ring gear. In that case, cleaning up the circuit supporting the solenoid will help. Another possibility is that there is a problem with the ground strap, making the circuit sluggish. In that case, working with the ground strap as previously described (or replacing it) will help. Certainly, installing the suggested supplemental wiring will have a positive effect, as it increases the available ground path. It the car usually cranks normally, and occasionally grinds, I would troubleshoot this particular problem in the following order (taking care to use the precautions mentioned in the earlier text).

  1. Clean and tighten the clip lead to the solenoid.

  2. Clean and tighten the Main fusible link (1st gens).

  3. Install the supplemental wiring

  4. Replace ground strap.

I actually replaced a starter motor because of the grinding problem, but it did not go away. As I worked through the above items (trying to solve another problem) the grinding became progressively more rare.

David has a 1st gen, but this should be similar to the 3rds, and he describes a good troubleshooting methodology. --Steve

Date: Tue, 12 May 1998 11:08:25 +0000
From: "David Lane"

Thanks to the people who responded with suggestions regarding my starting problem. This summarizes most of the advice given, and what happened. If you recall, I get a single, loud click when I turn the key to start, but the starter motor doesn't crank at all. I have learned a lot, and when time permits I will write a "primer" on first gen starting problems with the information that has so kindly been offered--plus what I have gotten from the shop manual.

Here is the update.

The local shop verified that the starter motor spins, which doesn't necessarily mean it has enough torque to crank the engine--but it is a step in the right direction.

At the suggestion of list members, I cleaned up all of the electrical connections to the starter motor, and verified that the battery clamps were clean and solid. I put a charger on the battery, which was in good shape.

For background, the starter has two big threaded terminals and one small clip terminal, all located on the solenoid. Turn the key to start, and 12 volts comes to the clip terminal. This activates an electromagnet (Mazda calls it a "magnetic switch") which engages the starter gear with the flywheel. The same mechanism also moves a fairly large contact plate which closes the connection between the two threaded terminals--one terminal takes the positive cable from the battery. The other is connected to the starter motor itself. When the connection closes, the starter motor should spin.

According to the shop manual, the terminal on the solenoid that receives the battery cable is called the "S" terminal. The other terminal, connected to the guts of the starter motor, is the "M" terminal (S & M anyone?).

One theory was that the contact plate in the solenoid was dirty, and not connecting very well. This seemed logical since when measuring from the S terminal to engine ground, I got over 12 volts, but when measuring from the M terminal to the engine ground (key on "start") I only saw about eight tenths of a volt. Power was getting to the S terminal, but didn't seem to be making it through the contact plate to the M terminal.

To see what I could find I pulled the solenoid off the starter motor to see if there was any reason to think the contacts were bad. It looked like a clean connection--at least what I could measure with a continuity meter. I couldn't get to the plate itself . It seems to be sealed in there. The shop manual said that with the solenoid off of the starter motor, you should get continuity between the M terminal and the body of the solenoid. This was so, so I put it back together, and looked further. For the record, list members told me you can get a starter solenoid separately.

I had received suggestions that the clip connector from the ignition may be loose. That seemed unlikely since I heard the solenoid "click" so clearly whenever I turned the key. But I decided to test it anyway. Maybe the solenoid wasn't operating at full strength due to a weak supply of power for the magnet. I cleaned the clip connection and pinched the contacts a little to tighten them.

No change.

I verified that I was getting 12 volts to the clip connector by turning the key to "start" and measuring voltage between the clip connector and ground. As an aside, there is a relay in the ignition circuit which clicks once when you turn the key to "start." Since the clip connector was not clipped to the solenoid (which would have made the much louder solenoid click at the same time), you could hear the relay clearly. The presence of voltage at the connector verified that the ignition circuit and relay were working, and eliminated the possibility of a problem with the ignition switch.

The guy at the garage said I should be able to trick the starter motor into cranking by using a screwdriver to short the incoming battery cable (S terminal) to the contact that receives the clip lead. This would connect 12 volts from the battery to the solenoid. The solenoid would activate, which in turn would connect battery current to the starter motor. This should cause the motor to crank. I have seen this done before, but there are usually a lot of sparks, so I was pretty ginger with it.

Nothing. No sparks. Nothing.

(Editor's note: A bad solenoid was my first guess, and this is exactly how I used to test it on my '69 Firebird. This WILL start the car, so make sure it is well supported by jackstands or preferably ramps. If not, you probably have continuity problems. The ground strap is one possibility; you may also need to replace the battery cables. The '69 ate starters like candy. Also clutches, tires, and gas. You could get a starter heat shield for it, and that cured my problem. The headers were wrapped around the starter and the heat just killed it. --Steve)

I clipped a small gauge wire to the incoming battery cable, and gingerly brushed the other end on an unpainted engine part--again looking for sparks.

Again, nothing.

I put a meter between the battery cable and the engine. It read 12.7 volts.

Hmm.

I disconnected the Positive battery lead from the S terminal, ran a small clip lead from the end, and brushed it against a body panel. Lots of sparks. I brushed it against the engine. Nada. This told me that the positive cable was doing its job.

At this point I started suspecting the ground strap was conducting enough through the engine to get a voltage reading, but not nearly enough amperage to get the starter motor spinning. Ground straps on 1st gens connect to the engine, but also to the body near the left side strut tower. I figured there may be somthing wrong with the engine connection.

I disconnected the battery ground strap where it connects to the engine, cleaned up the end, and reconnected it. Viola! The car easily cranked. I checked it out three times over about a half hour and the starter fired as normal. My "spark" test between the battery cable (S terminal) and the engine showed lots of sparks.

This morning, I went into the garage to clean up. I turned the key just to make sure everything was okay.

Big click. No crank.

Aaargh!!

Again, no sparks from shorting the S connection to the engine (again using a clip lead).

At this point, I am betting on a crudded up battery ground cable. I understand from past posts to the list that they can corrode internally and lose their ability to provide enough amperage to power the starter.

I will order a ground cable from Mazdatrix today.

Again, thanks to those of you who took the time to explain things to me. You are a patient bunch. I will post back when I verify that this was the cause of the problem

_________________

Date: Sat, 16 May 1998 19:26:00 -0700
From: "David H. Lane"

When I shorted the starter out (key on). There were no sparks. I have replaced the ground strap and everything is fine. Just for good measure (at the advice of Mark Schroeder) I ran three extra pieces of 8-gauge wire: one from the alternator output to battery plus; one from battery minus to the body; and one from battery minus to the engine.

Schroeder says that these cars (all gens) can be as much as a volt low under load, and that he does this extra wiring on any car he modifies. He thinks this lower voltage might effect some of the engine systems. I have written it up for the net, but wanted to get his approval before putting his name in the post.

After doing the wiring, I fired the car up and it did seem to be on steroids.

_________________

Date: Thu, 24 Sep 1998 16:42:20 +0000
From: "David Lane"

(David writes about a [1] or a [2], but this should probably apply to the [3] as well. --Steve)

A couple of things:

First, the layout of your electrical system:

Power for the starter comes from the positive terminal of the battery. The other end of the thick positive cable connects to the starter motor itself.

Power for the dash comes from a smaller wire that branches off the positive battery cable and goes to the "main" fusible link--part of five fusable links on the driver's side strut tower. You are getting dash lights so that is probably okay. If someday you don't get dash lights, clean the connections in the fusable link box.

Now, both circuits return to the battery negative side through the ground strap. This is attached to the negative battery terminal on one end. The other end is attached to the engine, and the middle is attached to the body, below where the fusible links are. Since you say you lose power to both the starter and the dash lights, the most likely culprit is the ground strap.

These ground straps corrode internally, so sometimes you can bend them a little and things will be okay for awhile. If you want to test it out before buying a new ground strap, carry a jumper cable with you. When you next have the problem, run the jumper from the negative battery terminal to an unpainted part of the body or to the engine. Try both. In effect, this will bypass the stock ground strap.

If the car starts with this tempory ground strap, order a new ground strap. Mazdatrix has them. You said you checked the battery terminals for cleanliness. Do the same for the other ends. You might also check to be sure the bare wires at each end of the main cables are not loose in the connectors.

If it doesn't fix the problem, and if you can manage it, remove the negative cable from the battery, run a jumper cable from the plus battery terminal to the starter motor (where the battery cable attaches. Looking at the motor from the rear it is the big terminal on the left side). Re-attach the negative cable and try to start the car. If it starts, the positive cable is at fault--either the end connections are not clean, or something internal is crudded up.

Most likely, you will find that the negative battery cable is the problem.

CAUTION: Do not work on the positive cable unless the negative cable is first disconnected from the battery. You could get significant sparks if the positive cable touches anything on the engine or body.

If you are in the mood to improve your electrical system, try the following:

Disconnect the battery. Disassemble and clean all contacts and connections in the fusable link box.

Run an extra ground wire (10 or 8 gauge) from an unpainted part of the body to the negative battery post.

Run an extra ground wire (same size) from the engine to the negative battery post. These two wires will improve electrical flow throughout the system. The standard Mazda wiring is marginal in that respect.

Run an extra wire (same size) from the alternator output (a screw terminal on the back) to the positive battery post. I understand from one of the gurus out there that it will make your alternator's life easier.

You might find it to be a cleaner installation if you use battery clips made to accommodate accessory wires. Auto sound shops have them.

When I did these things on my GSL-SE all sorts of little electrical anomalies associated with low voltage went away.

________________

Date: Fri, 25 Sep 1998 08:44:40 +0000
From: "David Lane"

A side note here. If the negative cable (ground strap) is crudded up, a volt meter will still read 12.x volts--something I discovered when diagnosing my own problem. The trouble is that enough juice will not flow to spin the starter motor when it is under load.

If you don't mind a semi-ignorant analogy, it is like measuring traffic flow on a single lane road and a multi lane road. Traffic on both roads ideally flows at 60 mph, but the multi-lane road delivers a greater quantity of cars to the destination in a given period of time. One of the reasons the positive battery wire (and the ground strap) is made of such thick stuff is to allow "multi-lane" electrical flow.

________________

Date: Fri, 31 Mar 2000 21:43:24 EST
From: MaxPesce@aol.com

> I have some problems when starting my 7,
> 
> When the car is hot, it is very difficult to start, it cranks perfectly but
> the engine
> is either not starting or very slowly raising to the idle rpm. 

Actually this was the subject of a Mazda TSB and is caused when starter motor and battery are heat soaked - the orig. wiring harness has too much resistance when HOT thus not allowing the starter to spin the engine fast enough and also causing enough voltage drop from the HOT battery (batteries produce less voltage when hotter than about 100f) to cause weak or no spark the Factory fix is upgraded cables. My 93 touring suffers same malady - drive for 20 min. or more park for 10-15 min - No start - wait 5-10 with hood up STARTS! also try turning Key to ON & letting Fans run for 2-3 min before starting when engine compartment is at maximum heat soak temp. works most of the time for me unless REALLY HOT Day. then must go to HOOD UP method.

Ignition Problems

Date: Tue, 22 Jun 1999 07:44:51 -0400
From: "Ryan Schlagheck" (ryan.schlagheck@worldnet.att.net)

I've sprung a leak in my Leading #2 plug wire, a Jacobs 8.5mm EnergyCore. The wires are 14 months old, and there is a pronounced slit in the plug end of the boot (versus the coil end) that lets the spark from the coil find a path to the block instead of to the plug. For those who have not had the misfortune of this problem, the symptoms are excessive backfiring under load, usually at WOT in 3rd and 4th gear. This happens at low boost too, as I'm running 10psi. With my open intake and exhaust, I'm literally dumping fuel out of the A'pexi tailpipe ;-)

When the plug wire was intact, the car ran to redline like a banshee. I'm wondering whether 10mm Magnecors feature better silicone/sealing to prevent the spark from getting through the shielding.

Battery Draining

Fro: Steve Cirian
Date: May 9, 2000

>I have the weirdest situation. My battery keeps on losing its charge after a 
>month or two. Ive recently replaced my alternator & battery twice as a 
>result. So I know it is not a problem with those two parts. I even had a 
>diagnostice test to make sure a draw on the battery is not occurring. The 
>only logical explanation for the battery losing its charge is because of the 
>10-minute fan cool down mechanism. I do like the feature of this cool down 

There are other logical explanations, such as a short somewhere that is slowly draining the battery.

The fans running should not be an issue since while they may be running off the battery when the engine is shut off, the battery will be charged again after you start the car up again. Also, they should not drain the battery much, unless their bearings are seized or some other cause that would make them very difficult to turn.

Unless you drive only a couple of blocks, the alternator should be able to charge the battery back up pretty quickly.

The cause of the drainage will probably be a component that will work even with the ignition switch off. e.g.- alarm (if installed), lights (dome, head, tail), cigarette lighter (I think this works when the ign. is off), stereo (if an aftermarket one wired in around the ign.), or fans (maybe a short in the switch that keeps current flowing even if it is not sending it to the fans?).

Or maybe a short from a wire that has been vibrated enough to wear through the insulation and ground out.

Have you done the fan mode? Double check that wiring and the switch.

Any other sorts of mods related to the electrical system, e.g.- extra grounding for the 3K hesitation problem?

How often do you drive the car?

How did you do the diagnostic test? I suspect it may not have been done right since the battery should recharge after you start the car up again.

There is an outside chance that there could be grounding problems. Check all points of all the grounds for corrosion. I am not an electrical engineer, but there could be some variation between potentials across the multiple grounds that is causing draining.

I think there was a TSB on the wiring harness, but that was related to heat soak/starting problems. See the TSB section of my site.

Cigarette Lighter Powered Devices

Date: Tue, 10 Mar 1998 10:40:49 +0000
From: "David Lane"

Valentine-1s tend to give false "Laser" warnings on RX-7s. It is caused by low voltage at the cigarette lighter plug. The V-1 uses the "laser" warning signal as a low voltage warning. This can occur even though the volt meter on the dash board is showing more than 12 volts.

I don't know why, but I can add to the discussion that most anything you plug into the cigarette lighter will feel the effects or marginal voltage, including cel phones, and other devices. There is something unusual about the way our cars are wired that causes this, but I don't know what it is, and I can't make much sense of it.

I have a brand new battery in my car (fully charged) and recently installed some new stereo stuff. There is an Eclipse head unit, small EQ and two small outboard amps (one Eclipse, one older Rockford). The power amps are wired directly to the battery and the head unit is wired to the power source from the OEM stereo. I was listening to the system (engine off) and wanted to open the windows. When the power windows on my car reach the end of their travel, they keep trying to move until you let go of the switch. This drops the voltage in the system. The power amps did not click off, but the head unit got so starved for electricity that it tripped its security feature and wouldn't turn back on until I re-set it.

I get the same voltage reading across the battery terminals as I do between the +terminal and the chassis, so I believe my ground strap is okay.

I can't help but wonder if maybe running a thicker wire from the battery to the circuit that powers the non-engine related electrical system might help. If anyone has tried something like this, or has more clues to what might make the accessory electrical supply more robust, it would be helpful.

________________

Date: Fri, 20 Aug 1999 15:58:53 +0000
From: "David Lane" (dlane@gigue.peabody.jhu.edu)

Since upgrading my ignition I started getting the dreaded laser alarm as the engine revved, so I called Valentine.

My V-1 was behaving quite strangely. It would false every time the tach passed 3k--like clockwork. If I held revs at about 3400 rpm the laser alarm would sound continuously, then drop out as the revs climbed above that. It was so bad I had to disconnect the V-1 entirely to keep from going crazy.

I came home and checked voltage at the fuse going to the cig lighter plug. It held steady at 14 volts as revs built.

When I called Valentine, the lady who answered the phone connected me with a tech who said that there was a quick voltage fluxuation that was too fast and too slight to see on a volt meter. However, the laser antenna is very sensitive and under the right circumstances it would result in an alarm. I asked if this was unique to rotary engined cars, and he replied that there were certain BMWs that also had this problem. In any case (as we have learned before) the solution is a small capacitor in the power circuit to buffer the power coming into the unit.

The Tech transferred me back to the nice lady who simply took my address and said she would send me a new lighter plug with the capacitor in it. No charge--even though my V-1 has a few years on it, and the problem is a result of a non-stock condition.

Valentine gets a good price for these units, but every time you work with them you are reminded that it is a good value.

For the record, there are two circumstances which will cause a V-1 to false on Laser (well, three actually).

1.  The laser signal is used as a low voltage alarm.  On cars that
    get a laser signal when the engine returns to idle, this is the
    probable cause.  You can usually get around this by pepping up
    your electrical system with extra grounding, and possibly an
    extra wire running from the alternator output to the positive
    terminal of the battery.  For older cars, new battery cables
    help, as does cleaning up the connections around the fuse [2] or
    fusable link [1] boxes.

2.  As above, the laser warning may be responding to fluxuations in
    the power supply.  It will false as the engine is revving.  The
    solution is to call Valentine and request a cigarette lighter
    plug with a built in capacitor.  Another solution is to get
    power to the unit directly from the battery. 

3.  You will get a false laser warning if you head your car directly
    into a red neon light--that is to say a red light emitted from a
    neon tube, as opposed to a headlight from a red Neon.  Never
    mind.  The solution to either situation is the same.  The V-1 is
    working normally.  

________________

Date: Tue, 24 Aug 1999 11:11:52 +0000
From: "David Lane" (dlane@gigue.peabody.jhu.edu)

I received the new cig lighter plug from Valentine the other day. For those who are interested, it contains a 1 micro-farad capacitor rated at 50 volts. The tech at Valentine said it had to be a ceramic.

The reason I was on the phone again was that it didn't solve my problem. I also tried hard wiring the unit directly to the battery, and that didn't help either. It seems like there is another possible cause for laser falsing on these units--one that I did not list in my earlier post.

The capacitor will take care of whatever might be coming through the power line, but it won't help if I am picking up something in the air. A few questions from the tech and I realized that the problem had started about the same time I installed the Magnecors. I didn' notice it for awhile because the problem doesn't show up until the car has been running for awhile. The tech suggested moving the V-1 as far away from the engine as possible. I did this on the way home last night, and the problem became more occasional--but still didn't go away.

I called Magnecor this morning. They agreed that it is possible, and (believe it or not) suggested that I check the grounding of the hood, since it is the only shield between the ignition and the V-1. I will do that tonight.

I asked Valentine if it would be possible to de-activate the (only marginally useful) laser feature on my V-1, and that's when I learned something interesting. The latest version of the V-1 (included in the latest upgrades) has a series of externally adjustable parameters that are not in the instruction book--kind of like getting error codes from our cars, or going through coded menus on a cel phone. You can disable the laser warning that way--and probably other things. Valentine service can send a fax with instructions.

I asked the tech if he minded me putting that info out on the net, and he said it was okay with him.

Needless to say, my unit is one of the older ones, so I would have to send it in, either for an upgrade, or just to have the laser board removed. I think I will try grounding the hood first. The guy at Magnecor said that even one or two ohms resistance between the hood and battery ground could negate any shielding effect the hood might have.

________________

Date: Wed, 11 Mar 1998 03:25:29 -0500
From: "Stephen Ziegler"

It is possible to see the same voltage from + to ground as you would see between the battery terminals even if you have a bad or high resistance connection through your ground strap. You wouldn't see the difference until there was current flowing through the ground strap and thereby dropping voltage across the bad connection.

You might want to try turning on your stereo while having someone rolling down the window as you described (although you don't want to keep the window regulator motor energized with the window all the way down for any appreciable length of time. Without the motor spinning, there will be no counter EMF (electromotive force) to oppose the current flow through it, therefore you will have a high current passing through the motor. This is why you see the power drain when the window reaches bottom and you are still holding the switch down).

Measure you voltage from ground to the + terminal and between terminals while the window is still bottomed out and the window switch down. If you see a difference, odds are that the ground strap has a bad connection, or even the - cable end at the battery has a bad connection. Hope this helps...

Wiring Devices to the Battery

Date: Tue, 10 Mar 1998 18:46:52 -0700
From: David Beale

David, I often do 2 way radio installs in vehicles. We find the way to be sure they will work well is to wire them with #12 wire directly from the battery. To make sure the equipment goes on/off when the car is shut down we use an accessory relay (30 Amp), with the coil wired to an accessory point in the fuse box (the radio fuse is good). It sounds like this would be a good option for the cigarette lighter/sound power setup.

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