Daytime Running Light (DRL)Conversion

Last updated: February 11, 2000

Date: Thu, 10 Feb 2000 20:40:24 EST
Subject: (rx7) [3]Fog Lights as DRL's


Objective: Modify the '93 RX-7 Touring Model fog-lights such that they automatically turn on when the engine is running and turn off after the engine is shut off. With the J.C. Whitney low-voltage controller, the Fog Lights operate at 9 volts to prolong bulb life. After this conversion, the fog-lights cannot be operated by the console mounted switch. According to the product brochure, this conversion meets Canadian DRL Standards.

This mod can also be applied to after-market fog lights. If you are installing the fog lights with this controller you won't have to run a wire to a cockpit switch or use an electrical relay (big bonus). Just follow these instructions and use the white (hot) wire from the DRL controller to supply the 9 volt power to both fog lights.

You could also get the 12 volt DRL controller and hook it up to the white parking lights in the front of the car to use them as DRLs. Just cut the hot wire at the lights and connect the power wire from the DRL controller box.

Some states don't allow fog lights to be on at the same time as your bright lights so this mod wouldn't really be legal but it's easy to get around. Just disconnect the DRL controller's power wire (or remove it's fuse) when you take it in for inspection and tell the guy the fog lights don't work. After the inspection hook them back up.

DRL bracket and controller


  1. Purchase DRL-Controller The controller replaces your fog lights 12 volt power source from the fog light switch with 9 volts that is supplied only when the engine is running. I got the controller from J.C. Whitney (312) 431-6102 or Fax at 800 537-2700. "Low Voltage Light Control" Catalog Item number 13HY5227R. I checked an older JC Whitney catalog and found yet a different part number. So, I'd advise interested parties to call JC Whitney and get a current catalog from which to order. Costs about $25, plus shipping. It is a small black box. They also sell a 12-volt controller for those who want full brightness from the bulbs. The low-voltage is supposed to prolong bulb life and reduce power requirements.

    Note: The DRL-Controller described here was manufactured by Hamsar Diversco, Inc., 5320 Downey Street, Burlington, Ontario, Canada, L7L 6M2, (905) 332-4094, and is their Model 70986 "Visi-Light". Since J.C. Whitney can switch suppliers, it is possible that another manufacturer's controller will install differently, particularly with respect to wire colors. Be careful.

  2. Disconnect the Console Fog-Light Switch You absolutely must permanently disconnect the fog-light switch inside the car. If not, the DRL-Controller fuse will blow when the fog-light switch is activated. Gently pry up the console and disconnect the fog-light switch and tape up the wire ends.

    DRL Mount Hole

  3. Find a Place to Mount DRL-Controller You must be in close proximity to the positive battery terminal, a spark plug wire and one fog light. I located a place immediately under the tip of the master cylinder on the driver's side fender bulge. There was a vacant 8mm x 1.25 bolt hole with enough space for the DRL-Controller. Double check the threads so that you don't strip them.

  4. Fabricate a mounting bracket for the DRL-Controller. I bought a piece of 18-gauge sheet metal at Home Depot and cut out a mounting bracket. You can also use sheet aluminum available at hardware stores. My bracket is the size of the DRL-Controller with a 1-inch by 1-inch tab off to one side. The tab has a hole drilled for a bolt. The tab is bent at about a 30-degree angle for better fitment. Prime and paint the bracket.

    DRL Bracket

    Drill two pilot holes in the mounting bracket and screw the DRL-Controller to it with sheet-metal screws.

    Install the DRL-Controller & Mounting Bracket in car - at this point the DRL-Controller is attached to the mounting bracket, and this assembly can be installed with a single bolt if you used at the location described above. I put a layer of electrical tape between the bracket and the car to minimize corrosion.

    DRL mounted controller

  5. Verify Wire Colors - The wire colors can be very confusing. The wires coming from my DRL-Controller had the following colors and functions. Your colors and functions may be different, so check them.
    Green:   Wrap Around Spark Plug Wire
    Black:   Ground Connection
    Red:     Fused, Hot From Positive Battery Terminal to DRL-Controller
    Orange:  Hot to Hi-Beam (not used in this mod)
    White:   9-volt Hot (labeled "Low Beam")

  6. Disconnect Positive Battery Terminal and Connect Wires Again, pay particular attention to wire color.

    DRL battery connection

  7. Reconnect Positive Battery Terminal

    Start Engine See if fog-lights come on. If not, check the fuse. If it has blown, check the functions of the black and white wires connecting to the fog-lights. Also make certain that the console fog-light switch has been disconnected. At this point your fog-lights should be fully functional DRL's.

  8. Tidy Up - Once everything is working, use tie-wraps to secure the various wire runs. Replace Battery Cover.

DRL finished picture

Note: The installation described above should NOT work if the wiring diagram shown on page E-1 Section Z of the Shop Manual is correct. Page E-1 shows the fog-light ground wire to be Black, and the hot wire is shown as White. However, when I initially installed it this way, my DRL-fuse blew when I started the car, indicating a dead-short. So I then treated the Black wire at the fog-light as the "hot" wire and this solved the problem. The only way I understand this could happen is if the Shop Manual reversed the White and Black wires in the diagram. As I have only a rudimentary electrical knowledge, comment would be appreciated by an electrical engineering types.


Date: Thu, 10 Feb 2000 20:40:24 EST

I purchased the DRL controller at JC Whitney, the catelog place. Their telephone number is 1-800-837-4227. Call them for a catelog (their part numbers are always changing.)


Note: Also see the Fog Light Rewiring Page for info on how to rewire the fog lights so they will come on w/o the headlights.


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