KJL

When the headlights are turned on, they both open no problems but the motors continue to operate for about 5 seconds and makes a knocking noise. The headlight operation is smooth and the noise only begins when the headlight has reached the fully open or closed positions. What could be causing this?

Ed Ramberger

Broken nylon gears inside the motor.

KJL

It is odd to me that both are broken.

z06scentair

Its not odd, rather common.

Out of the four c4's we currently own all have had to be replaced. Did I mention one car has 34 miles on it?

KJL

Oh my... Sounds like a design flaw. Where can I get info on how to repair?

KJL

Did you replace with nylon or metal gear?

Cliff Harris

Check this video. He starts out with demonstrating the noise that is the problem:

z06scentair

I use nylon gears as the motor was designed for.

All Corvette parts houses sell these at a cost of around $30.

kimmer

If it opens and closes but you have motor run on it's not the gears. The motor should shut off after its job is done. Could be headlight control module or headlight switch in the car. My old headlight motor did this and the internals were like new.

KJL

Great video!!! Thanks. That is what my lights do and how they sound. The the other posts, my guess is the motor continues to run because the gear teeth are missing? His did the same thing in the video and when the gears were fixed, the run-on condition stopped. I guess I will start with the cheapest fix and work on from there....head light control module.....really? Funny and scary at the some time.

KJL

What one did it end up being and how did you repair?

kimmer

It looks like its coming down to the switch. With the new motor it would only open, after the module it open and closed but still have run on. I took the motor to the other side and plugged it in and it works flawlessly so its got to be the switch.

KJL

Damn... I would think a switch issue would impact both sides. Where is the module located?

kimmer

On the front fender well on drivers side.

KJL

Great, thanks for insite, I may pull one of the lights this week to see how the gears look for starters.