Headlight motor continues to run after end-of-cycle

[mrparty]

Sorry to be making so many posts around the same time, but my Reatta has developed another minor issue.

 

The driver's side headlight motor will continue to run for a few seconds after the headlight is already in the up or down position. I can tell it has already started to strip the plastic gear inside because the headlight has a little trouble going up fully sometimes, so I have already ordered a repair kit with a brass gear.

 

My question is this: is there a switch or contact in the motor that tells it when to stop that may have failed on my car (and causing the stripped gear in the first place)? I would hate to make a repair only for this to happen again.

 

As a second question, could somebody tell me the function of the bell crank arm and what symptoms a failed one would have? I don't think my issue is there, but it could be. 

 

I will try to get a video of my symptoms a little later.

[2seater]

As far as I know, the limits of the motor are based on current feedback, not a switch inside. There is a timer that does stop the motor if it doesn’t run into a physical stop. 
The typical failure points are the three plastic rollers inside the actuator or the bell crank arm getting rounded out. Actual gear failures would be unusual

[Ronnie]

Below are the two things that usually go bad. Crumbled rollers inside the gearbox and the rounded out bell crank arm that attaches to the shaft.

 

You will want to replace the rollers, sometimes called bushings, when you open the gearbox and possibly the crank arms depending on condition. Unless your plastic gear is stripped, which is unusual, you won't need the brass gear.

 

Don't take the screws out of the electric motor on the end of the gearbox. It only makes the job harder. Carefully remove the three screws to open the gearbox as shown in the last photo. Instructions for removing the headlight motors from the car are in the How-To guides here on ROJ.

 

 

[mrparty]

2 minutes ago, Ronnie said:

Below are the two things that usually go bad. Crumbled rollers inside the gearbox and the rounded out bell crank arm that attaches to the shaft.

 

You will want to replace the rollers, sometimes called bushings, when you open the gearbox and possibly the crank arms depending on condition. Unless your plastic gear is stripped, which is unusual, you won't need the brass gear.

 

Don't take the screws out of the electric motor on the end of the gearbox. It only makes the job harder. Carefully remove the three screws to open the gearbox as shown in the last photo. Instructions for removing the headlight motors from the car are in the How-To guides here on ROJ.

 

 

Thank you for the photos. Would it be a good idea anyway to replace the plastic gear with the brass one since I have already ordered? I'll have to go check the crank arm on that side and see if that might be the problem. Do the symptoms of bad bushings vs bad crank arm differ? My headlamp will bounce up and down a little when extending before fully coming up (sometimes). And the motor sounds like it continues to run for a few seconds after headlamp is fully up or fully down.

[Ron Walker]

Frequent issue with most headlights. The bouncing is probably a bad and rounded crank. The continued running is likely due to shot bushings. The shot bushings look like "rice" as shown in the photos provided by Ronnie.

[Ronnie]

2 hours ago, mrparty said:

Would it be a good idea anyway to replace the plastic gear with the brass one since I have already ordered?

If it were me I would stick with the white plastic gear if it is in good condition. I see nothing to gain with the brass gear. I've not known of one of the white plastic gears failing... but maybe they have.

 

I see a potential disadvantage to using the brass gear. The right and left headlight motor/gearbox assemblies are different. When you open the gearbox on one side (the left if I remember correctly) the white plastic gear and drive shaft assembly will pull right out with no problems.  On the other side, the white gear must be forced past the worm gear that drives it to get it out of the gearbox.  The plastic gear has enough give to allow you to do that but the brass gear may not. Otherwise you have to remove the electric motor from the gearbox to move the worm gear out of the way. When you do that you take a chance of breaking the small screws that hold the motor to the gearbox. It is common for those screws to break. It's a big headache to get the broken screw out so you can install a new screw.

 

I believe the brass gears were intended to be used in the Pontiac Fieros that were prone to breaking the plastic gear. That system used switches to shut off power to the motor. If the switches failed, and the motor didn't shut off, the white plastic gear would break. The Reatta has a different system with a electronic headlight control module that senses the current driving the motor. It will shut off the motor before the plastic gear is broken in normal operation. It will also shut the motor off after a certain period of time if the motor keeps running due to bad rollers or a bad crank arm.

 

 

[Ron Walker]

Agree with Ronnie. Not only are those small screws hard to get out when broken, but they are difficult to replace. I had to go to a machinist to make the screws - the threads are uncommon (sorry, I don't recall the thread count).

[2seater]

I have not seen the brass replacement gear, but if it is made without the non-hobbed area like the plastic, removal/installation should be okay. I think there are reasons there are a selection of fusible links, in a manner of speaking. The bell crank and rollers could both be stronger, but in doing so it will move the failure point somewhere else. 

[Alchemy333]

@mrparty let us know what resolves this issue for you. I have the exact same deal going on with my drivers side headlight.

[mrparty]

1 hour ago, Alchemy333 said:

@mrparty let us know what resolves this issue for you. I have the exact same deal going on with my drivers side headlight.

Will do! I've got a new bell-crank and nylon bushings in the mail and will report back!

[mrparty]

On 5/17/2023 at 12:04 PM, Alchemy333 said:

@mrparty let us know what resolves this issue for you. I have the exact same deal going on with my drivers side headlight.

Well I just completed the repair of the headlight motor and replaced the crank arm and it works great now!

 

The old bell crank did look like it was starting to wear out (I'll post a picture of it tomorrow), and all of the nylon bushings inside the motor were completely disintegrated. The nylon gear inside the motor was totally fine.

 

 

Thanks a lot to @Ronnie, @2seater, and @Ron Walker for their advice. They were right on the money with what was going wrong. 

[Alchemy333]

@mrparty do you have a link or part number for what I need to order for this repair? Thanx!

[mrparty]

3 hours ago, Alchemy333 said:

@mrparty do you have a link or part number for what I need to order for this repair? Thanx!

Yes! Here is what I bought.

 

HEADLIGHT CRANK ASSEMBLY REPAIR KIT BUICK REATTA | eBay

[Alchemy333]

My internals were pretty good... and a bit different I think. So I took the risk of leaving it alone and lubed everything up. So, 130 bucks for the arm and a bolt lol. Didnt need the rollers. But no more running and they go up and down nice and smooth. My lever was completely rounded out. Pretty easy job... if you follow the direction.

[Ronnie]

Glad you got it fixed. Looks like someone installed a different gear at some point. Nothing wrong with that if it works OK.