I bought my son an used truck. The truck’s dashboard wasn’t lit in some places and the gauges were all over (some of them not registering at all). Here is what it looked. The engine was on when I took this photo. The tach doesn’t register at all, battery gauge is bad and oil is way off too.
A quick search on the web revealed that this is a common problem for GM vehicles of that vintage. Basically, the stepper motors fail in the gauge cluster. So I ordered replacement parts and started to disassemble the cluster. That’s where I found why my check engine light doesn’t work:
A fix was easy and quick. I just had to peel the electrical tape off. Fortunately, there was no actual problem so the light now works but stays off when the car is running.
The replacement procedure is pretty straight forward. There are four pins to solder for each motor. The two larger holes are alignment holes so you know how to position the new part. The kit I have ordered had seven motors but my gauge cluster only had six as my truck doesn’t have the transmission temperature gauge. Once all is in place you need to reassemble the cluster. The stepper motors have a hard stop that will allow you align the needle. You can also use painter’s tape to mark the position of the needles before you take them out. Here is a photo showing work in progress with one motor left to replace.
I wish I have ordered a replacement bulbs at the same time. Unfortunately, I didn’t think about that so couple of weeks later, I had to take the whole gauge cluster apart to replace the bulbs. Those are the blue ones two photos up. For some reason the backlight lights are incandescent and all other lights (check engine, control lights, etc) are LEDs. The bulbs are surface soldered so they require a bit of finesse but it doesn’t really matter if they are a 1/8th of an inch off. They will still work fine.