turboren

OK, here's the story. I've had this problem with the headlights on my 91 A/T since I bought it Charleston, SC, in the summer of 1999. When the headlight cluster switch was turned to the parking light position, nothing would happen. If it were turned further to the headlight position, only the headlights would come on. The only way to get the parking and instrument lights to come on was to turn the retractor switch (above the light switch) on, to keep the headlights up.

The guy I bought it from didn't know there was a problem, as this was his first (and probably only) FC. I knew better, however, so a couple days after I bought it, I tried to figure out the problem. I knew the headlight switches were prone to failure, so I grabbed a spare from my stock and went to replace it. Upon pulling the cluster panel, I found that the harness going into the back of the left (headlight) cluster switch had a jumper wire running from the retractor "up" wire (red/blue) to the instrument panel illumination wire (red/green). At first, I thought, "What idiot did this? No wonder the lights don't work right," and promptly dispatched the offending jumper with my trusty soldering iron (whoever did it at least had the sense to solder the connections). I then installed and hooked up the switch, fully expecting the lights to once again operate normally. Wrong! The HL were the only lights working again, and this time, of course, I couldn't turn the IC and P lights on by using the retractor switch (although, the retractor switch did still operate as it should).

Thankfully, I had the foresight to NOT reinstall the trim panel completely, but I did have to remove the cluster switch from the panel. No sweat, I figured, two bad switches can't be that uncommon, especially since I couldn't remember from which car I had taken the switch originally. I tried another spare, but that had the same results. No way, I thought, I can't have THREE bad switches. So, I pulled the switch from my daily driver, which, obviously, was known to be good. Still no luck.

So, after some choice words, and feeling rather foolish for having disconnected it in the first place, I reconnected the jumper wire and reinstalled the old switch (which I had confirmed to be working in my daily driver). Things were back to working again, just not as they should. I was done for the day, and decided to tackle the project some other time.

Well, that time never came, as I never drove the car (had 65k on it when I bought it, and has 69.5k today), and I ended up getting orders to Iceland in the fall of 2001. I thought of taking the car with me to Iceland, but decided the salted winter roads would probably ruin it. I ended up leaving it with my cousin back in Charleston, and left him instructions on how to turn the lights on.

I moved from Iceland to Norfolk, VA, this past June, but wasn't able to pick up the car for another month thereafter. When I got it back, it had about 500 more miles on it (he obviously hardly drove it, either), and the lights were still not operating properly. In fact, they had gotten worse, to the point where the switch had to be beaten on to get the HL down. I figured the contacts on the retractor relay were going bad, which was confirmed when I later pulled the switch apart. I picked up the two spare switches I had before returning to Norfolk.

After a few nights of driving, I noticed a smell that I couldn't place at first, but then realized it smelled like a hot iron (one you press clothes with), when the lights were on. I felt the panel in the vicinity of the cluster switch, and it was hot to the touch, but not hot enough to melt, of course. The next afternoon, I took the panel off to find that the heat sink for one of the components (transistor, I think) had melted completely through the plastic housing. Thinking that the jumper wire must be causing the overheating problem, I tried again to remove the jumper wire, and again had no luck. I tried the spares, but only one worked, so I used it. The next night, I could tell the replacement switch was also getting too hot, so I removed it the following afternoon, routed the wiring to outside the panel, and connected the switch, leaving it hanging from its harness. After another couple days, I realized I couldn't risk having the one good switch I had left burn up as well, so I decided to use the original switch to turn and keep the lights on, and then I'd use the spare to turn them off, plugging each in for its assigned task.

I continued this way for about two weeks. Then, finally, on the 18th, my household goods arrived. I spent a couple days organizing and unpacking, and tonight found my trusty 91 FSM, and set out to cure this problem once and for all.

First thing I did, of course, was remove the jumper wire. Then I broke out the DMM and chased voltages and continuities. What I found was puzzling. According to the readings I was getting on the cluster switch harness, everything should have been working properly when using a known good switch. I tried jumping various terminals to see if I could get things to work. Interestingly, I could get the P and IC wires to work if I jumped across the red to red/green and red to red/black wires, respectively, but could not get the white/green wire to power the same wires when it was jumped from; this despite the fact that the white/green wire was showing +12V at all times (as it should). I even removed the cluster harness and jumped the wires at the connector from the front wiring harness, with the same results. The next junction back was the fuse block, and I had already determined all the fuses to be good by both visual and continuity checks. As I had already been at this for four hours, I decided I had nothing to lose by pulling and replacing the fuse.

And the clouds parted, and the cluster switch did say, "Let there be light!" That was it, all along. A stupid fuse, which looked good, and actually was, just wasn't making a good connection because it was corroded.

Lessons learned:

1) Just because you have enough voltage doesn’t mean you have enough current.
2) If it seems that something very major is wrong, it's probably something simple.
3) Whoever wired in that jumper in the first place was REALLY an idiot!

Hope this was both amusing and informative.

Ren

Icemark

Some great lessons there, thanks for sharing!

razorback

i cant believe i read that entire post. always check the fuses. its usually the most simple things that are the problems.

Icemark

well that is one of the points... if you jsut visually checked the fuse, you wouldn't see the problem... only by actaully replacing the fuse did it solve itself.

razorback

that is true. but when soemthing doesnt work right first i take out every fuse and look at it to see if it is in working order.

SonicRaT

iTrader: (6)

I hate stupid stuff like that. I spent like 5 hours after replacing my switch trying to figure out why my headlights wouldn't retract properly, after troubleshooting and replacing it I remembered I disconnected the motors to keep them from frying with the old one. Doh.

turboren

Way back when I first bought the car, I did look at it with a flashlight, and the burnable part was still intact. I checked the fuse for continuity, and it was fine. I even removed the fuse and performed the same checks. It was the corrosion on the blades that caused the problem. I didn't figure that out until I replaced the fuse with another, which was still corroded, only less so.

Ren

HeavyFoot86

Ren, thats hilarious, I'll keep that in mind next time something goes bad on my ReX.

Chris

midnightbluefc

iTrader: (19)