nuke61

I have a problem with the drivers side headlight on my car. The headlight will not open about 50% of the time, and it seems to be due to torque. What I mean is that when I turn on the headlights I do NOT hear a grinding noise like I did when my wife's Coupe needed to have the gear replaced on one of the headlights. Instead, the headlight simply doesn't open. The light goes on, and if I open the hood, and then use the mechanical actuator to open the light just a half turn or so, the motor takes over and opens the light fully.

This leads me to think that the headlight motor is torquing the headlight to the closed position such that in the open direction the torque needed to open the headlight just isn't enough to open the headlight. The short question to this long explanation is this: is there a torque adjustment for the headlight motor, or does this mean I need to buy a new headlight motor? To reiterate, there is no grinding noise, so I don't think it's the headlight gear, although I haven't looked at it. It really seems to be an issue of overcoming starting torque/current, since if I open the headlight manually just a bit it works fine.

nuke61

I take this to mean that there's no closing or opening torque adjustment for the headlight since there are no replies.

How about this question then... what causes the headlight motor to stop turning when it's at the full closed or full open position? A switch? A relay driven off of current flow?

JOEY P

I have the same type of problem with mine....When I start the car when it is dark outside and the headlights go up only one does....The drivers side goes up but the passenger side does not until I turn the ignition off and then back on and then the passenger side goes up after several attemps somtimes......Could someone tell me whats going on....Thanks

dbstephens

I have had the same problem occur after repairing the damaged plastic gears in our 2001 with brass replacements. It took about a year before the symptoms developed after the repair. The lights still work fine, with the ocassional "lock-up" in the closed position.

I have compared the motor tension to my 2004 Z06, which still has its plastic gears and find that they are not driven as hard against their mechanical stops as the 2001 with brass gears. This may be due to the inherent flex in the cheap plastic gears (which eventually causes them to fail anyway).

There is no way to adjust the "stop torque current level" in the headlight control modue, without internally modifying the electronics. I don't feel that a new control module would be much different unless its internal electrical tolerances are skewed to the high side of the current range.

If we had this failure each time that the lights were turned on, I would suggest replacing the headlight control modue.

Every so often, open the hood and tweak the manual adjustment counter clockwise, so that it is not driven down so hard against its mechanical stop. Remember the electronic actuator control operates on a specific current level to the motor. If it sees this high current upon trying to open the door, it thinks that the light are already up and shuts off the motor drive. Running current in both directions is low, until it gets to the mechanical stops at either end. The current then ramps up, due to a stalled motor, and the controller shuts the drive voltage off.

Don

nuke61

Thanks, I'll try the mechanical operator adjustment and see if that helps.

LoneStarFRC

It also wouldn't hurt to try lubing ALL the headlight hinges too. I do this about once a year or so and use a small oil can (cheapo Globemaster brand) and squirt a couple drops of motor oil into all locations. Wipe up any excess with a clean cloth. I still have my plastic gears on my '99, with a backup brass gear from Rodney just in case.

robvuk

Preventive maintenance is a good thing.
You're very pretty too.

LoneStarFRC

Thanks. I'll tell her next time I see her.

Zilla likes compliments too.

vizette

I've found some interesting "events" by adjusting the **** and then turning the lights on/off.

I would try playing with the manual up/down ****. In other words, when it's down, if the **** is locked tight one way, loosen it a few turns. Maybe it's a touch out of adjustment and sometimes torques down too tight?

Play with this until the light moves freely on it's own. While doing this you'll notice they may get out of sync opening/closing. Again, I just toyed with it until I was satisfied.

If I understand correctly, when you turn the lights on the **** doesn't spin at all until you help it right? If it's spinning initially and the light doesn't move I would guess the gear.

-Rich

nuke61

It's the first guess... when I place the switch to turn on headlights, the drivers side ****-thingy doesn't spin at all. If I turn the **** by hand just a bit, the motor will take over and open the headlight. I haven't compared the "tightness" of the drivers side headlight to the passenger side headlight, but I'll check that to see if there's a difference.

LoneStarFRC

One other thought. While you're checking, try to get a really good look at the cover plate on the gear housing of the motor. See if there is any separation or signs of bulging. If you can reach it, try to see determine if the cover is loose/cracked or partially separated. The later C5s all have the cover plate glued and/or riveted in place and I'm wondering if your side cover is not being held firmly in place, maybe the main drive gear inside is "walking" or moving away from the drive pinion gear while under load. The earlier C5s all have three screws holding the cover plate in place.
Wouldn't hurt to check.

Junkman2008

Any of you guys get this resolved?

hightest

I had all of the same problems, and tried all of the same cheap fixes, but the only thing that actually repaired the issue for good was to replace the headlight control module. The module is extremely overpriced, but worth it compared to the headlight headache.

Junkman2008

Price?

Mixxit

hightest

The module cost me $112.00 "Canadian". The module did have to be shipped in from the US, so shipping and duty would have been added to the price. I would imagine the price would probably be $60 to $80 over there.
Maybe you guys should check with Gene Culley here on the forum, he's usually better priced than any dealer!
Hope this helps.

Bluefire

It could be a combination of the drive signal from the headlight control module has been slightly degraded over time, and the added weight from the brass gear requires more torque to start. These two things together could have brought the start current to below the minimum level.

Giving it a "bump" with the manual **** fixed it. A new HCM fixed it. I wonder if a new plastic gear would too. Just a thought.

Jackflash

I have a 98 that has had the same symptoms for over a year. Left light door opens fine, right does not. I replaced the drive gears with brass units but they had the same old rubber cushions inside which promptly wore out. I see now someone is making them with no rubber just a slot to engage the tabs on the output side.I also replaced the headlight module with no effect. I noticed that if I turn the engine off prior to turning the lights off they will reopen about 90% of the time which led me to the conclusion that the motor was over torquing the linkage. Like you stated just a 1/4 turn of the manual **** toward the open position and they work fine. You might also check the condition of the plastic stop pads. You can flip them over if they are worn. Hope you find your problem.

kevin40zx

I just replaced my drivers side gear with a metal gear and now I am having this problem.

toddm

I've never licked this problem, but mine work most of the time now. I've replaced both gears with brass ones, but couldn't find an epoxy/glue that wouldn't come apart over time. So I clamped the housing shut with some metal plates and screws.

Solved the coming apart problem, but then my driver's side headlight started refusing to open some of the time. When this happened sometimes retrying to open them worked. If that failed I could manually loosen the adjustment and it would sometimes open the rest of the way on its own as nuke61 described.

What finally "solved" the problem for me is being patient. I always start the car and then wait 5 or more seconds to turn on my lights. This seemingly gives enough time to let the other electronic systems fully turn on.

When doing this my headlight raises properly 99% of the time. I guess there's some issue with providing enough current to the motor and waiting allows the motor to receive the full amount.