1994 Coupe
1. Turn headlights on -- Left light rotates approximately 80% of the way and stops. Right side is fine.
2. Turn headlights off -- No response from left headlight. Right side is fine.
3. I manually close the left headlight. Closes fine.
4. Cause of problem (I think) - I replaced gears a few years ago and kept hearing a funny noise when turning lights on/off. I never diagnosed the noise at the time (lazy mistake on my part) mainly because I do not drive much at night and fixing it got put low on the priority list. After inspecting this morning, I now think the left headlight was rubbing against the opening in the hood at the 80% location and the assembly needed to be moved over about 1/16-inch. Over time, for some reason, it got stuck and now I have this problem. I assume the circuit to open the light is different than the circuit to close the light. The fact that it opens would indicate the motor is good?
5. So, I loosened the six bolts and re-aligned the assembly with respect to the opening in the hood. Clearance is much better now, but problem continues in that is stops rotating at about the 80% location and no response when turning off.

Questions:
A. Why would it mechanically stop now? A broken tooth in the gear? That would be the easy fix but I do not think that is the problem.
B. Is there a mechanical adjustment on 'range of motion' that can be adjusted?
C. No response when turning off - This is the biggest concern and I assume it is an electrical issue now. Did I burn out something up after turning the lights off last night and the system kept trying to close? I did not manually close the assembly last night.
D. Electrical troubleshooting - I can do this if given good instructions. I am a retired mechanical engineer by trade and have a volt/ohm meter; however, I need good instruction.

Thoughts.

Thx!!

K.C.

 

-Do you have a copy of the '94 FSM?
-Can you use the manual know to fully open the light as well as to close it?
-If so, open it manually and see if will it then close when you turn off the lights?
-When you compare movement of the manual ***** for each light is there more play in the problem one?
-Is there now any mechanical obstruction to interfere with operation of the light?

I think you may need to open up the mechanism to see what's going on inside.

 

Thx for the response.
I have NOT tried to open it fully with the manual **** and will try that next.
Good idea. I somewhat remember when I first turned the know to close it, that I turned it the wrong way and it was rather difficult to turn. However, I need to confirm with a specific test.
I am very confident that there is no obstruction anymore.
I agree with your last comment......I wanted to troubleshoot as much as possible before opening it up...…

When I replaced the gears a few years ago, I did use the metal gear and I have not activated the lights that much …… so, I would be surprised if it was a gear problem.

That being said, it is not a big deal to remove the assembly and open it up.

 

The motors are designed to stop when they reach an obstruction or bind. If you remove whatever was causing the bind, it should return to normal operation. If it's still stopping in the same spot, I suspect you haven't removed the obstruction.

Good luck.

 

Troubleshooting - Day 2

With the car not running, I did the following:
1. I turned the manual **** and the headlight opened to the same location and stopped. I repeated this several times. I looked for obstructions and binding and I am not seeing anything.....but will continue to look.
2. I then noticed that the assembly had a some play in it when I 'gently' rocked it up and down in the direction it is designed to travel. So, while in the 'stuck' position and the **** not able to turn, I gently rocked it and it seemed to break free.
3. The manual **** and was now 'free' to turn in the direction to completely open the headlight all the way to full open position!
4. I then turned the **** to completely close the assembly.
5. Next step.....turn on the car and see what happens.

With the automobile on:
1. Turn on headlights.
2. Same results: Right headlight fully opened. Left headlight stopped at same location (about 80% full opened).
3. The manual **** would not turn.
4. I then 'gently' rocked the unit, and, for lack of better words, it became loose again,...., and I was now able to easily turn the **** until the unit was in the full open position.
5. With ignition still on, I now turned the switch to the 'off' position and both headlights responded and closed fully! So, that is good.

So, my thoughts for today for the left side:
A. Motor is good and works in both directions.
B. Wiring to the unit is good. (i.e. no shorts)
C. The problem is more mechanical in nature than electrical.
D. A broken tooth in the assembly? Such that it gets to the point and stops; but when I rock it up and down, it is able to bypass the dead spot and open fully? Why would it then close?
Note: I replaced the large plastic gear with a metal gear a few years back; so, I somewhat perplexed that the metal gear would fail.
E. If broken tooth, it could still be a gear internal to the motor?

I will play with it some more and continue to look for possible obstructions, etc.; but I think the next step is to remove and disassemble.

Open to other ideas.

thx

kc

 

 

Problem Solved! Maybe?

Well, I am submitting this as closure to the problem, albeit, it may only be temporary.

I went back out and continued to activate the lights, then when the left side got stuck, I would gently rock it until the manual **** could turn, and then turn the **** until the light was fully opened. Then it would always close.

I did this about five or six times.....then, all of a sudden, it opened...... all the way! Whaaat? I have no idea. Then it closed.....then it opened all the way.....etc. for about 5 times. I have never been so excited to see my headlights go on.

fyi.....I left out of previous posts.....one of the things I did in the very beginning was spray lubricant on all rotating surfaces.....could it have just needed time to penetrate? Since I rarely use the headlights, could some corrosion set up and it bound up at the same location? Anyway, I then sprayed lubricate generously on all rotating parts and opened and closed the assembly many times.

After all this was completed, I close the hood and did it one more time.....WHACK!....no way.....I immediately open the hood, turned the lights off, and then turned them 'on' and 'off' with the hood closed at varying degrees until I think(?) I found one possible obstruction.

I now think (?) the initial culprit that started all of this could have been the large rectangular shaped electrical connected located between the headlight assembly and the fender wall. I then tucked the connector away from the light assembly and tie-wrapped it to the interior of the fender. I am not sure why this connector was not secured in a more better location to begin with.....interestingly enough, the same connector on right hand side was not secure either. So, I reset both connectors to be further away from the light assembly. I then tested it again with the hood closed and it seems to work fine.

I do not have an explanation as to why it suddenly began to work again after not working so many times. That does not make sense and it concerns me that there may still be a deeper problem internal to the motor assembly. As a retired engineer, this does bother me,...…; as someone living on a retirement budget, I am happy for now and will hold off on removing the assembly and taking it apart.

 

Good to hear you are making progress with the issue.

Coincidently due to light snow today I pulled on the lights and the RH headlight stuck partly open. Ordinarily I would just order the gear & bushings but too damn cold out for that R&R.
I'll take a page from your play book and do an inspection & apply some lube...

 

FYI, on the underside of the big connector there is a small slot. This slot slides onto a corresponding plastic clip which protrudes from the top of the side-marker light housing. If it's not there, I would assume that someone broke it off trying to get the connector off.

 

Good comment....Interesting.....I kept looking for a clip to attach the connector to and could not find one either side.....maybe I can pick one up one of the vette websites.

 

it does make sense to apply lubricant to rotating shafts, bushing, etc.; especially when they are so exposed to the elements

 

Last week my car to was doing the 80% headlight and if you manually rocked light it would go, after pulling the headlight motor what I found was the plastic gear had a crack in it. But you said you already installed the bronze gear so a crack is unlikely but a bit of junk from a bushing starting to break down? Any way there working for you.

 

Congratulations. You've solved the problem. When you first wrote that you had cleared all obstructions, well... It's not always easy to tell.

BTW, the left side electrical connector also came loose on my '96. It was enough to stop the rotation in mid swing. The tiny plastic factory push-in clip doesn't work very well after 22+ years. Once I got the connector out of the way, just like yours all is well.

Your zip tie is a permanent solution.

 

I have not looked for a replacement 'push-in' clip, and may look into it just to keep everything clean and original. It would be nice to have a photo of it or part number. I will check out the FSM but am doubtful.

I assumed the obstacle could be discovered with the hood up; did not consider troubleshooting with it closed.

I have opened and closed the lights every day since and without question, it is 100% better. I kept hearing an odd noise for quite a long time and basically ignored it (really bad decision; especially for a mechanical engineer by trade)!

Moving forward, I will now spray some lubricant on all the rotating parts of the light assembly as part of my maintenance routine when changing the oil.