Headlight gear keeps failing
Thread Starter
Intermediate
Joined: Aug 2007
Posts: 46
Likes: 1
Headlight gear keeps failing
Any idea why a headlight gear keeps stripping out? I'm looking at my third replacement since 2019, this side only. Will switch to the metal one this time but there has to be something else going on. Have never had to replace driver's side. Thanks.
Thread Starter
Intermediate
Joined: Aug 2007
Posts: 46
Likes: 1
Thank you. They keep telling me nothing is wrong, just bad gears but I'm not sure. Does the headlight control module have anything to do with the body control module thing? I had aLOT of work done with that last year because I was having issues with the headlights and running lights on that same side.
Safety Car
Joined: Feb 2002
Posts: 4,942
Likes: 7
From: Gaffney, S.C.
If the outer housing gets worn where the driven gear rides it will cause the worm gear to ride toward the outer edge of the driven gear and wear it out quicker. You can make a bushing for the housing if you have the skills.
Race Director
Joined: Apr 2007
Posts: 11,150
Likes: 890
From: South Western Ontario
Headlight control module is on passenger side below the headlight. It is completely separate from the BCM. The headlight module controls the motors on-off based on the load on the motor. Basically, they hit the stop and the current goes up and the module sense that and shuts them off. Personally, I think some modules need more current than others before shutting the motors off because some people have no issues with gears and others have lots of issues. A module powering the motor longer as the current rises would put more force into the gear and damage it quicker.
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Instructor
Joined: Nov 2021
Posts: 228
Likes: 63
so you are saying that you are getting the "grinding noise" with three different motors after install? If that is the case, I would inspect for the presence and condition of the four bump stops. IF these are missing or broken the motor may be over extending itself causing stress on the plastic gear. Alternattively, it depends on what brand you are using. aftermarket brands are terrible quality. I had the same problem with autozone motors until I finally bought a GM oem part and the issue was gone.
If, however, the motor just stops working (and does not have the grinding noise) then manually turn the motor counter clockwise a quarter turn. you should be good to go then. (I also dealt with this issue. sometimes the motor just needs to have its tension releived slightly and it works perfectly.)
If, however, the motor just stops working (and does not have the grinding noise) then manually turn the motor counter clockwise a quarter turn. you should be good to go then. (I also dealt with this issue. sometimes the motor just needs to have its tension releived slightly and it works perfectly.)
Race Director
Joined: Apr 2007
Posts: 11,150
Likes: 890
From: South Western Ontario
FYI, the motor can't over extend and damage the gears. If you take the arm off the motor then it will run in circles forever.
A temporary fix is to take the arm off and turn the manual **** until the shaft makes a half-turn and then putting the arm back on. The motor will then stop in new spots on the gear instead of the worn-out spots.
A temporary fix is to take the arm off and turn the manual **** until the shaft makes a half-turn and then putting the arm back on. The motor will then stop in new spots on the gear instead of the worn-out spots.
Race Director
Joined: Oct 2004
Posts: 12,859
Likes: 4,656
FYI, the motor can't over extend and damage the gears. If you take the arm off the motor then it will run in circles forever.
A temporary fix is to take the arm off and turn the manual **** until the shaft makes a half-turn and then putting the arm back on. The motor will then stop in new spots on the gear instead of the worn-out spots.
A temporary fix is to take the arm off and turn the manual **** until the shaft makes a half-turn and then putting the arm back on. The motor will then stop in new spots on the gear instead of the worn-out spots.
Racer
Joined: Nov 2003
Posts: 430
Likes: 60
From: Central KY
Headlight control module is on passenger side below the headlight. It is completely separate from the BCM. The headlight module controls the motors on-off based on the load on the motor. Basically, they hit the stop and the current goes up and the module sense that and shuts them off. Personally, I think some modules need more current than others before shutting the motors off because some people have no issues with gears and others have lots of issues. A module powering the motor longer as the current rises would put more force into the gear and damage it quicker.
Instructor
Joined: Nov 2021
Posts: 228
Likes: 63
Race Director
Joined: Apr 2007
Posts: 11,150
Likes: 890
From: South Western Ontario
The stops for the motor are a metal tab with a very hard piece of plastic over them. The plastic does dick all for cushioning the motor stopping. The motor makes the same amount of over-current force before the module stops it regardless of it hitting the plastic or the metal.
If the arm misses the stops, the motor keeps running and the headlight keeps going up and down, kind of like it's "winking" at you. Nothing in the rest of the assembly can get over extended and stress the motor.
If the arm misses the stops, the motor keeps running and the headlight keeps going up and down, kind of like it's "winking" at you. Nothing in the rest of the assembly can get over extended and stress the motor.
Instructor
Joined: Nov 2021
Posts: 228
Likes: 63
The stops for the motor are a metal tab with a very hard piece of plastic over them. The plastic does dick all for cushioning the motor stopping. The motor makes the same amount of over-current force before the module stops it regardless of it hitting the plastic or the metal.
If the arm misses the stops, the motor keeps running and the headlight keeps going up and down, kind of like it's "winking" at you. Nothing in the rest of the assembly can get over extended and stress the motor.
If the arm misses the stops, the motor keeps running and the headlight keeps going up and down, kind of like it's "winking" at you. Nothing in the rest of the assembly can get over extended and stress the motor.
Nevertheless, we will have to agree to disagree on this one. I recently had issues with my passenger side motor to the point where my dealership received assistance from GM engineers. This is precisely the description they provided me....ie specifically that many issues can result by the motor "over torquing" and "freezing" or "locking up" because of improper or lack of bump stops. Accordingly, when a motor is frozen, slightly backing off the motor manually more often than not resolves the issue.
happy motoring!
Race Director
Joined: Apr 2007
Posts: 11,150
Likes: 890
From: South Western Ontario
LOL, the factory stops are not rubber. You've been had by somebody. I've had the factory ones on my car in my hand and they are definitely a hard plastic. My car has 160k miles and the stock bumpers have a dent from the arms. If they were a soft material they'd have been destroyed in that time. I think you're confusing harness with brittleness.
Considering how long it's been since a new GM had pop-up headlights, I doubt anyone who works at GM doing engineering has actually been involved with the design of this type of headlight mechanism.
As I posted first time, the modules seem to vary in their shut-off torque. Some cars destroy gears every 10-20k miles while others will go 100-150k miles without gear issues.
Originally Posted by rodneydickman
These are made from the same type of plastic GM used. Others in the market place are made from a brittle plastic and do not last!
As I posted first time, the modules seem to vary in their shut-off torque. Some cars destroy gears every 10-20k miles while others will go 100-150k miles without gear issues.
Drifting
Joined: Jul 2015
Posts: 1,844
Likes: 375
From: San Jose, CA
OP, I would recommend posting photos of the inside of that motor assembly so we can see if there're obvious issues. As others have said, T-brackets help hold the system together. And as others have said, some control modules don't properly read the amperage, and some folk have actually hacked up their own solutions using arduinos or the like.
Instructor
Joined: Nov 2021
Posts: 228
Likes: 63
LOL, the factory stops are not rubber. You've been had by somebody. I've had the factory ones on my car in my hand and they are definitely a hard plastic. My car has 160k miles and the stock bumpers have a dent from the arms. If they were a soft material they'd have been destroyed in that time. I think you're confusing harness with brittleness.
Considering how long it's been since a new GM had pop-up headlights, I doubt anyone who works at GM doing engineering has actually been involved with the design of this type of headlight mechanism.
As I posted first time, the modules seem to vary in their shut-off torque. Some cars destroy gears every 10-20k miles while others will go 100-150k miles without gear issues.
Considering how long it's been since a new GM had pop-up headlights, I doubt anyone who works at GM doing engineering has actually been involved with the design of this type of headlight mechanism.
As I posted first time, the modules seem to vary in their shut-off torque. Some cars destroy gears every 10-20k miles while others will go 100-150k miles without gear issues.
One is never too old to learn new information or perhaps a different understanding/interpretation especially when it comes from a source such as GM itself.
Cheers and happy motoring!
Race Director
Joined: Apr 2007
Posts: 11,150
Likes: 890
From: South Western Ontario
The fact is that the stops are a hard plastic, not a soft rubber. Manually turning the motor isn't a permanent repair when you have to do it again the next time it sticks shut. Been there, done that, replaced the gear to permanently fix it.
You're the one who quoting me telling me I'm wrong but I'm the one who's being argumentative? Whatever you say....
You're the one who quoting me telling me I'm wrong but I'm the one who's being argumentative? Whatever you say....
Melting Slicks
Joined: Dec 2004
Posts: 2,847
Likes: 1,144
From: Sleepy Hollow- NJ
The bump stops are 100% hard plastic. I just pulled mine off before parking it for winter to inspect them. I flipped them around so the unwarn sides were facing up. I also just bought a backup pair for future replacement. Also hard plastic.
I went through the gear stripping scenario 15 years ago. Finally had enough and swapped to brass. Then my glue job failed me. So I decided to just replace the whole unit with a salvage motor. No issues since.
I went through the gear stripping scenario 15 years ago. Finally had enough and swapped to brass. Then my glue job failed me. So I decided to just replace the whole unit with a salvage motor. No issues since.