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How to tell if headlight motors are going?

Kevin M

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Probably beating a dead horse here, but I some how couldn’t get anything to come up with my specific problem. I went to a car show last Wednesday and when I put the lights on only one light went up. Turned it on and off three times then they both went up. Went down with one push. Saturday after another show they worked fine. So is my headlight motor going? Or maybe just a random glitch. 

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You could have a bad headlight switch but both headlight would act the same.

The headlight control module individually controls each motor,  but the headlight modules seldom fail.

There are a couple of things that go wrong with the headlight motor and actuator arm....

As a general rule........... the original factory arms/bellcranks slowly get worn to the point that the headlight door will not open

Think like a Phillips screw that the slot gets worn....sometimes it will catch,  sometimes it won't..... in the case of the bellcrank....as it wears, there is a delay in the door opening.

Next you have the 3 plastic rollers inside the big white gear.   They lock the gear to the output shaft.   They initially crack,  then the action of the parts starts grinding them into smaller pieces.

They eventually end up almost like powder........the roller parts are trapped inside the gear,  so as the plastic chunks get smaller, there is more slop in the system,  but the headlight doors will usually

open because the plastic pieces/chunks/powder be displaced to one side and that is enough for the motor to open the door.

The last thing that is starting to appear after 30 years......the output shaft is no longer permanently attached to the cast piece inside the gear.   When made,  the shaft was pressed into the cast part

and that is a perfectly acceptable method of assembly,  but there is a lot of torque on the motor parts and the UP/Down action of the motor, results in turning that shaft one way then the other and

that seems to be causing they to come loose.

If I was able to do some tests at your car,  it could be determined which of the above has failed,   now the good news.

When you take the headlight apart to fix either of the problems.........replace both the bellcrank and the rollers.   You have a problem and you will need to fix it.......so it does not matter which one failed

It takes about 45 minutes to take one apart and install the new parts,  so if you replace both,  you will not need to go in later to do the other.

Example.......I sell the KIT (steel bellcrank, 3 new rollers, UPSTOP plastic nut and instructions) for $40.    Just the bellcrank sells for $35 or just the rollers $5

I am thinking about including a 1/8 dia rollpin with the kit so the owner will have that part should they find the shaft is spinning inside the casting.

Hopefully the attached photos show all the problems.




shaft 6.jpg

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on my 89 , sometimes the rt light wouldn't work and sometimes would work 10 times in a row ! sometimes it wasn't getting power.I checked the 2 relays under the hood , but both were good ! was thinking about wiring them both to the left side power .ALL THE PARTS ARE NEW ! 

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