Tech Area

Strange Headlight Behavior, 87/88

Question: The car's an 87, so it has the later headlight arrangement. I replaced the nylon cylinders in both lights last year, courtesy of Rodney Dickman, and they've been working fine until recently when the passenger side intermittently refused to lift. No motor noise, like there's no power getting to the motor. The headlight came on but the mechanism remained obstinately unmoved. I found by hand-cranking it up a few turns with the headlight switch off it would then activate when switched on. After this, it was fine for a couple of days, going up and down normally, then it stopped working again. Another hand-crank got it going, but on switching off it refused to go down. Hand-cranking it down a touch would allow it to activate again and close. I've checked best I can for loose wires and connections but all seems ok. Whereabouts of the control module remains a mystery. I know it's buried deep down around the front end somewhere, but all attempts to find it have so far failed. Can anyone shed any light (excuse the pun!) on the cause of this? It's driving me nuts.

Answer: The brushes and armature are probably wearing. The motors have a natural "phase" where they normally stop. Turning the knob puts them "out of phase" and on a new contact patch. They will usually work for a short period of time until returning to their natural "phase".

Sometimes cleaning the brushes and armature is all that is necessary. Sometimes wear is too much and replacement is called for. There are no known replacement brushes at this time.

The electronic control module is in the cavity between the fender and the outside of the "headlight box" metal and attaches with 2 screws on the dr's side. Sorta behind the side marker light. Access is by pulling back or removing the inner fender well.

Although called "electronic", the module is NOT solid state. It contains 3 relay switches with points that can be filed/cleaned. That will sometimes/sometimes not bring them back to life.

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