Here is a little background, I bought my 1988 Fiero GT in March of 1988. It has the original 2.8 Liter V6 with the Getrag 5-Speed and currently has 27,600 miles on the car. Hasn't been my daily driver in over 25 years, mainly autocross and car shows. According to the 1988 user manual and the factory service manual, there is no up-shift light on the V6, the wiring diagram only shows the up-shift circuit on the 4 cylinder.
While driving to an autocross this past Sunday, the up-shift light started glowing! It wasn't full bright, only the right half started to glow. It didn't follow any kind of pattern, just light up for about a minute and went out. When I arrived at the autocross, it appeared again remained half on when I turned the car off. Huh? Turning the ignition on (engine off) and off again the light when out, and hasn't come on since.
So, this morning, I pulled the cover off the gage cluster and found that there is NO LIGHT OR SOCKET IN THE UP-SHIFT OPENING, IT'S EMPTY! WTH? My first conclusion was perhaps sunlight making it's way into the back of the gage cluster, I was driving into the morning sun when it happened, but not when I parked the car in the pit area. Now, I can reproduce a similar effect with the back cover off of the cluster, but not with the cover back in place. I have not found any evidence of scorching, damage, or delamination of the printed circuit board, that might show evidence of a short circuit, in fact its in excellent condition and no fuses are blown.
Car runs great, no check engine light during or after. Heck, I even placed First in the combined Vintage Class! But I'm at a loss to explain why the up-shift light appeared? As I mentioned earlier, it was not full bright, only the right half started glowing, and I'm sure I wasn't hallucinating.
Correct, headlights and parking lights were off. As were the turn signals.
Burned out resistors leave an awful odor, not sure what a burned diode smells like, but I don't smell anything. So, I guess it's time to pull the IP cluster... It's certainly possible that it was sunlight, I was able to shine a flashlight through the vents and some light made it through the up-shift light, but nothing like it appeared on Sunday. Perhaps that's all it was, but I like to have a definitive resolution.
Currently, all lights and gauges work.
I'll report back when I pull the IP Cluster. Thanks folks!
Originally posted by dbober: LOL! I wish I could have snapped a picture!
Haha! Yeah, all I got is light somehow getting to the back side of the bulb hole. Somehow. Either sunlight at the perfectly correct angle, or another bulb that was bleeding over. Despite how unlikely, that's all I got.
Good luck with the hunt and I hope you figure it out.
Either sunlight at the perfectly correct angle....
I forget which bulb it is (or lack thereof), but I have one that gets sunlight and glows. Requires the perfect sun angle and time of day! Kind of worried me the first time it happened but I doubt I've seen it more than once every couple of years.
So, I pulled the IP Cluster and found nothing that would have caused/leaked/whatever light into the Up-Shift light box. No scorched traces on the plastic circuit board on the back of the IP or on the Tachometer. The shift light is on the top right side, and there is nothing near it accept the right turn signal light that might have shorted or burned. The plasic blocks that seperate the lights were in place and their rubber gaskets are still plyable and positioned correctly, no light leakage. The tachometer board is sound, no burned components.
I considered covering the open socket with tape, but chose not to. I want to see if it happens again and grab a picture.
Removal was easy, so this was a good oppurtunity to clean and polish the gauge lens.