ok here's a question, the last two times I have taken my 94 C4 out for a run when I bring it homeand put it back in the garage and turn off the parking lights in get a thump-thump over and over for about 10 seconds. If I turn them back on it stops immediately until I turn them off and it starts all over. It just the parking lights not the head lights.. any ideas or has this happened to anyone else?

 

I had a similar experience with my 1994 C-4. I first noticed that the noise was the coming from my headlight motor when I turned on my headlights. They still opened properly, but the headlight motor would continue make a thumping/gear spinning noise for a few more seconds after they opened. Later I noticed as you did that the headlight motor also made a thumping/gear spinning noise when just the parking lights were turned on too. This may be something unique to the way the system was designed in which the headlight motor is activated, but not engaged when just the parking lights are turned on. I would suggest you turn on your headlights with the engine turned off and listen to determine if the noise is coming from one or both of the headlight motors. After doing some research on this forum, I was able to read previous comments on this issue and observed YouTube videos which provided detailed step by step information on how to replace the the headlight motor gears and the three nylon pellets which eventually disintegrate over time. I found both of my headlight motors were in need of gear and pellet replacements. I replaced them with two brass motor gears which included the three nylon pellets. Both will need to be replaced together as the pellets will eventually wear down to powder and the gear teeth may also tend to break off over time. I purchased my brass gears from Corvette America, they currently sell them for $59.99 each. You can also purchase a nylon gear which includes the three pellets also for $29.99. I would suggest you replace both gears while your at it since they will both eventually fail if they are the originals.

 

My 95 does this exact thing. I haven't researched it yet. Please update if you figure it out.

 

Yep, the thumping is the noise of the headlight motors continuing to turn even after the lights have reached the end of their travel. If the gears and pellets are still good, they would hit the end and then shut off immediately. Chances are 99% that the gears are fine and it's just the three pellets inside that hold the gear to the shaft that are bad. This isn't a hard or expensive fix. There are tons of threads on this and a couple good youtube videos.

 

Thank you for the responses. This place is a great resource with good people that are alwayswill to help.

 

Just did my headlights. Had the pellet kits. Once i tore it down i needed bushings too, so i was robbed at $35 for the car set.Gears were fine. Driver side was dust in the gears, pass side still had the intact green gel. Rebuilt both sides - work great now. One is delayed a little compared to other side but i think it looks cool if they are not timed correctly.
Had alot of info on doing the fix, however i can can tell you the driver side is easy. Pass side is a little tricky getting gear out (worm gear stops it). With a little tap, the worm gear cut the back of the gear and it fell right out. Just line up the teeth when you put back in. A little hard to explain, but DONT LOOSEN the motor or worm gear itself - no need to.

 

Thank you for the information. That's going to help me a lot.I am going order the repair kits this weekend.