A friend helped me (OK, I helped him) replace the nylon bushings in my '89 driver's side headlight motor. (I had the passenger side one done a couple of months ago when my car was in the shop for some other work. I asked them to do both sides, but they only did the one.) It was not going up all the way some of the time. The nylon bushings were indeed dust - literally. We put it back together and tested it and it worked fine when I left his house.

Then, after making a stop on the way home, it was dark enough to use the headlights. They came up with no problem. At a second stop, when I turned off the lights, the driver's side motor kept turning for about 5 seconds after the light was down, bouncing the light all the while. When I turned it back on, it did the same thing. After I got home, I checked the alignment, thinking maybe something hadn't been tightened enough and had vibrated loose, but everything seems fine... except for the motor not wanting to stop when it's supposed to!

Any ideas of what may be the problem?

Thanks,
Cathy

 

Many things are possible here. From my experience, I would venture to suggest someone either failed to replace all the thin, metal shims inside the headlight motor, or failed to seal the gear case correctly. It's also possible one or more of those bushings moved off seat between the metal splines that rotate to raise and lower the lamps.

I do know that if the headlight motor gear case is not sealed properly, it will allow the main drive gear to spin off-shaft and cause the problems you mentioned.

That's why it's always a good idea to MANUALLY raise and lower the headlight assembly a couple of times to ensure smooth operation before you apply power to the headlamps. And when you FIRST open the gear cover to replace the bushings, mark the reference point on the gear with a permanent marker so you can ensure proper positioning before you seal everything back up.

 

Just to clarify...the motor is doing its job correctly. The headlamp goes up with no problem and it goes down with no problem (We DID operate the motor manually before reconnecting on the headlamp assembly to assure smooth and correct operation, and a few times more after reinstalling on the car to check the alignment. Then we plugged in the motor and tested it electrically and it worked fine a couple of times before the problem started.)

The problem is that after the headlamp is in the correct position, the motor keeps going for about 5 seconds. Whatever is supposed to let the motor know to stop turning isn't working. How does the motor know when to stop?

Cathy
'89 Coupe

 

There are limit switches or "stops" inside the motor that tell it to cut on/off.

But let me repeat again that you should check the motor assembly carefully, even if it means pulling it all out and starting from scratch.

Mine did the same thing yours did and it turned out to be the motor housing itself was not screwed together properly. It was hard to tell at first, but a closer inspection revealed the problem.

Just because the motor is opening and closing properly, does not mean it's assembled properly.

As I said earlier, there are limit switches inside the motor housing itself that tell the motor it's traveled as far as it can in either direction.

If those are not making good connection it can also cause the problem you're describing. To fix that, you have to remove the headlight motor.

Be carefull opening the cases, leave the armature in place, if you remove it you will have a devil of a time getting it back in place. You will see 2 sets of contacts, take a piece of sandpaper and clean them off...try not to move them.

Clean the mating surfaces of the housings and apply a line of RTV around them, then reassemble the housing. Reassemble motor back into headlight and you should be good to go.

Also while apart you should look at the gears, if they look visibly worn it would be an opportune time to replace them.

I hate to have you go through all this again, but I don't see any other alternative than going hands-on again. Hope this helps.

 

Thanks for the info. I was hoping it would be something easier. I'll check it out.

Cathy
'89 Coupe