15 September, 2004
Jeff Bihn, Marcus Hall, and Jeffrey Ho See have contributed suggestions to the MR2.COM archives that describe modifications to remedy this condition. Unfortunately, these are mostly text descriptions. I'm not very skilled when it comes to electrical mods, so photos are always appreciated in addition to text descriptions and/or schematics. Hopefully the photos I've included in this guide will help others who wish to make this modification.
Finally, remember that this is only a guide -- not gospel. What you do to YOUR vehicle is YOUR responsibility. I do not endorse, approve, authorize, or otherwise encourage you to make alterations to your vehicle. Be careful, and recognize the dangers associated with modifications to your vehicle's critical systems, like electrical, engine, brakes, etc.
Please contact me if you have comments or suggestions about the article or the project, or if you find errors on these pages.
My goal was to modify the wiring to enable the fog
lights to run completely independently of the other lights. My only
concern is that they run unswitched, e.g., they run with the key in the
off position. It's more useful that way, but I hope I don't accidentally
leave them on some day and kill my battery. There is an indicator light
in the gauge cluster, but I'm not sure if that is enough for me. My
memory seems worse every day.
First off, you'll have to decide how much stuff to remove from your front
trunk. I removed the spare tire and the entire inner lining to make
working simpler, but I guess you could get by without entirely removing
The red ovals indicate two areas (there are others not in the photo)
where you'll need to remove fasteners holding the retaining brackets for
the fuse panel. In my case, I also needed to remove the reinforcing brace,
a multi-armed brace that attaches in several places near the center of the
trunk. I'm not sure this is entirely necessary, but it made it easier to
work on the back of the fuse panel, and it enable me to clean out some
rustproofing "goop" that was sprayed everywhere.
Once the top cover is removed, you can see the fog light relay in the
upper right corner. If you enlarge this photo, you'll notice that the
printed schematic on the case of the relay lists four terminals: 1, 2, 3,
and 5. This was a bit of a problem, since both the BGB and Marcus Hall
referred to terminals 1, 2, 3, and 4. Not a biggie, but disconcerting for
a novice electrician.
I chose to remove the fog light relay, since I was planning on soldering
some leads attached directly to the relay terminals.
Turn the fuse panel over, and remove the back cover. This is made more
complicated by the four clips that are used to retain the cover. To free
them, you need to work a small screwdriver in from the top and unlatch the
locking mechanism for each clip.
Once the cover is removed, you'll have lots of multi-colored wires within
The photo focuses on the four wires leading to the fog light relay. I've numbered them according to the terminal numbers on the relay. The two wires we are interested in are #2 and #5.
Wire #2 (red w/yellow stripe) only receives power when the low-beam
headlights are powered on, so we need to remove that dependency. Luckily,
#5 is hot at all times. All we need to do is cut Wire #2 and splice it to
Wire #5, as shown below:
NOTE: Splicing Wire #2 into the black w/orange stripe wire (which goes to the FAN MAIN relay) instead of Wire #5 above will provide power only when the ignition is in the ON position, an excellent suggestion for preventing accidental battery discharge. Thanks go to Ricky Benitez at MRControls.com for this and numerous other MR2 tips.
After carefully taping the splice to prevent any shorts, you can replace the back cover, and re-mount the fuse panel in its original location. Replace the relay and you're ready to try it out......NOT!
Ah, yes, another Toyota mystery. All you seem to have accomplished is
that the fog lights will now come on even if the high beams are on. Not exactly
what I was looking for. I pored over the BGB's wiring diagram, but I got
lost until I re-read Marcus Hall's guide that mentions that
"some" MR2's run the ground wire over to the retract relay. This
must be the year. Why this is so complicated is a subject for discussion,
but another time. I'll avoid speculating and get on with the fix.
Move your attention to the left side of the front trunk, and you'll see a
HUGE, bright green electrical component with a mass of wires going into
This is the retract relay, and your job is simple. Slide the relay off its mounting bracket, remove the connector from the bottom, and locate the only wire in the bundle that's red with a black stripe. It's the second wire in from one of the connector edges.
You simply need to cut this wire and ground it. You can choose another
splicing operation as we did with the fuse panel, but I chose to ground it
to a frame bolt. It required slitting the wire covering open, cutting the
wire, splicing a length (about 6") of wire fitted with a ring
connector, then taping the wire bundle back up. Here's the finished
|I fastened the ring connector to the same bolt that two
other wires were grounded to, right near the wire bundle:
This solved the mystery, and now the fog lights are totally independent of the other lighting systems.
1993 MR2 Turbo