MFaulkner

Howdy,
My chilton's manual says that a "headlight control module" controlls my lights (on/off, how long they go up/down). But doesn't say WHERE it is located. Any of you guys know? Do I even have it ('90 formula)? Thanks!

(my motors stay on too long)

CheezX

Its right beside the wiper motor on the firewall. Looks like a black box. My 90 formula has one

BlackBeast'88

If your motors continue to run when you shut the lights off then it's probably the bearing in the motors. Since your car is 13yrs old you'll need to replace the crumbled bearings in each motor with some steel bearings.

MFaulkner

Thanks! I'll take a look at that tomorrow. Just if you wanna know, one motor is more or less working (the other is sitting on the workbench until I make some new bushings). The light raises and lowers, but the motor keeps running after its up. I suspect the control module uses a timing capacitor, which is probably off-tolerance by now, and the motors run longer than they should. It shouldn't be hard to adjust the module to stop the motors when they're all the way up (i hope).

deadbird

I don't know quite how the module works myself but, it will cut power upon resistance (I'm assming some form of circuit breaker). As BB'88 stated, if the motor is freely spinning after it is fully raised, the bushings have most likely turned to powder as normal. Even though the bushing dust creates enough resistance to lift the housing, it's not enough to make the module cut the power to the motor. Once you fix the busings, everything should be alright. I just finished redoing mine a short while back because I had the exact same problem.

89_305TransAm

The HCM is located on the firewall behind the brake master cylinder. Its a square black box with two? plugs on it i think. It says "guide" on the box.

MFaulkner

Thanks, I didn't have any trouble finding it today, opened up the box... a relay, 4001 Quad two-imput nand gate, tantalum capacitors, a chip I haven't identified, two (15-20 amp?) mosfets, and the usual transistors and resistors, etc. It's more than the simple RC timing circuit I expected. That rules out off-tolerance aluminum electrolytic caps.

I didn't know that, about turning off when the motors encounter resistance. I only have one motor in, so the net resistance should be half of normal... maybe that explains the long run time? I'll get another module from a junkyard to compare/experiment.

MAybe I should just was my hands of the whole business and make my own circuit board...