Question: No power to right Headlight Motor (???)

[Jerrys95vette]

I have a 1995 Base C4 Corvette. The headlights worked fine but the other day after a short 20 mile trip the right headlight motor lost power and would not close. I smelled a burning smell and saw sticky black oil drip from the bottom of the motor. (Very few drops and a very foul oder) I thought I burned it up but it tested fine when hooked direct to battery. The light bulbs work and have not had any problems. Manual turn worked find. No grinding or slippage. The left side only gets short bursts of power and will move one or two inches when I turn the interior headlight switch off and on. By doing so I can get it (left) to eventually close. Checked the Big fuses for L & R headlight motors and they are ok. My multi-meter hooked to the left fuse port for that headlight motor shows a short burst of power to the left motor when I first turn on the headlight switch. (Maybe a second or less) When connected to the right side fuse I get nothing. I then replaced both headlight motors and gears as I wanted to upgrade to aluminum gears anyway (nothing was wrong with the nylon ones) and still same exact problem. Tested both (new) motors direct to battery and they work fine. Then did same battery test to the old motors and both worked fine.

Could this be the headlight motor control module forward of left tire? I have ordered a new one in hopes that it is. I have hear that these have problems from time-to-time on vettes for some reason.
If the new control module does not correct the problem where do I look next? (Interior headlight switch???) Does it control the left & right motors independently?

In Summary; short burst of power to left motor and NO power to right.
What is wrong? These things worked fine for over a month. That’s how long I have owned the vette.
Thank you kindly for any suggestions, tips, or commentary.

 

[Antz81]

The headlights worked fine but the other day after a short 20 mile trip the right headlight motor lost power and would not close. I smelled a burning smell and saw sticky black oil drip from the bottom of the motor. (Very few drops and a very foul oder) I thought I burned it up but it tested fine when hooked direct to battery.The light bulbs work and have not had any problems. Manual turn worked find. No grinding or slippage. The left side only gets short bursts of power and will move one or two inches when I turn the interior headlight switch off and on. By doing so I can get it (left) to eventually close. Checked the Big fuses for L & R headlight motors and they are ok. My multi-meter hooked to the left fuse port for that headlight motor shows a short burst of power to the left motor when I first turn on the headlight switch. (Maybe a second or less) When connected to the right side fuse I get nothing. I then replaced both headlight motors and gears as I wanted to upgrade to aluminum gears anyway (nothing was wrong with the nylon ones) and still same exact problem. Tested both (new) motors direct to battery and they work fine. Then did same battery test to the old motors and both worked fine.

Could this be the headlight motor control module forward of left tire? I have ordered a new one in hopes that it is. I have hear that these have problems from time-to-time on vettes for some reason.
If the new control module does not correct the problem where do I look next? (Interior headlight switch???) Does it control the left & right motors independently?

The smell and oil is probably from the motor overheating, and drawing too much current. This could have caused you control module to fail. Keep the new right hand motor in. Its your call if you want to use the old left motor or not. (I'd use the new one since you have it). Once you get the new control module in i would say everything should start to work normally again.

 

[Jerrys95vette]

Antz81

Antz81,


I installed a use (but working) control module last night. Both headlight motors opened and closes just like they should. I tested it several times and was so happy.
But then…
I drove the car 6 miles and when I parked and turned off the headlight switch neither of the headlights went down. There was no sound, jerk or twitch. I then checked the connections and fuses. All looked fine. I manually closed each headlight, turning the knob, it was smooth and easy.
I then turned the headlights on and both motors opened the headlight doors just as it should. Again, I switched off the lights and the same problem, nothing happened. So, now they are wide open and will not close.
I find it hard to believe that the control module went out that fast, although possible, but hard to believe.
Could I have another electrical problem that would cause the module to fail or somehow have blocked the system from reversing the polarity?
They both worked, open and closed. I drove a very short distance and now they won’t close. (??????)
Please, any help with this would be greatly appreciated. I don’t want to keep throwing money at control modules only to find out my system is going to screw the up.
Also, is there a way I can test the control module to see if in fact, that is my problem (again)?
Thank you kindly for all you help and support.

 

[Antz81]

Since both lights are doing the same thing now I don't think it's going to be the control module stopping your headlights from closing this time.
you should have a dark green wire from your headlight switch. Check that this has 12v on it when the switch is in the off position. The yellow wire should only have 12v on the on position. Neither should have any voltage if your lights are set to park.
The diagram below should help.

 

[Jerrys95vette]

Antz8

Thank you kindly for your suggestions.
Yes... Someone told me about that so I checked it last night.
My results:
With the key in the ON position and leadlight switch ON, I get 12v from the yellow wire.
With the key in the ON position and leadlight switch OFF, I get 12v from the Dark Green wire.

I also checked both the red wires and get 12V regardless of any other on/off activity. I assume that this is telling me that the interior headlight switch is working properly in that it is sending the correct signals all the way to the harness plug for the control module.
After tracing the wires looking for any issues, checking the large RH/LH 30 amp motor fuses and testing the green, yellow and red harness wires, I am completely stumped.
I spoke to a guy that has a business that rebuilds the motors and has successfully repaired control modules in the past. I told him what all I had checked and he was stumped too.
So, I broke-down and just bought a new control module. It should be in next week. I will post the results after I give it a try. I hate that I have thrown so much money at this problem and if I can’t figure it out I’m just going to drive it like it is. That saddens me and irritates me at the same time.
I just can’t think of any other electrical connection that could be fouling up the motor controls, but I am certainly open for suggestions.

Ps, after testing the yellow, green & red wires, I put my original control module back in. It did the same thing it was doing before I removed it; no right motor power and only slight short bursts of movement opening/closing the left motor. I assume that if I had a problem somewhere in the wires coming from the module to the headlight motors the left side would not have started to close.
If you or any other CAC members have any further suggestions for me to try I would gladly do so. I am so grateful for your input and welcome more.

PPs, I have another problem that I will post separately.

 

[Jerrys95vette]

Problem resolved

Update to my headlight motor problems.
I finally broke down and bought a new headlight motor control module. Now everything thing works as it should. After tracing all the wiring, testing every end for power and pulling out what little hair I have left, the control module seemed to be the problem. Apparently, the used one I put in was NOT in working order as I was promised. However, the seller did refund purchase & shipping. Good honest guy and does very professional rebuilds.