putting the 90 back together and the most problem has been the headlights. a little stuff but frustrating. i had to replace the frames as the right side was damaged and left side was broken too. while i had them out i replaced the bushings inside. when i did, the left side was har to get the gear out but did and the right side came out very easy. when i put them back in the car the left side works perfectly but the right side doesn't open all the way. there is an adjustment screw and was wondering if anyone (hopefully joel is reading this) that knows the proper way to adjust the tension on the gear. thanks dave

The '90 model has different headlight motor set-ups than my '85, but adjusting them should be the same.
If the headlight is not going up all the way, turn them on, then turn the adjusting knob until that headlight goes all the way up. If that doesn't take care of it, then it's possible you got the main frame for the headlight out of whack.
Does the headlight come on, and rotate, then the motor stops running, as if it was completely open?

thanks for answering joel. its not the frame or the travel that needs adjusting. there is a screw on the motor itself that tightens the splined shaft to the gear in the motor. it must be too loose now so motor doesnt turn light all the way. was wondering if any one knew what the proper way to set that adjustment. i'll havr to see if i have the bushing instructions laying around and maybe they might have it.

I'll need to look and see if I can help come up with a solution, Dave....unless someone else chimes in...

checked service manual and all they have is how to adjust when you remove the whole assembly from car. this is one of those things that is probably harder to get the answer than it is to do.

i was right...took about two minutes to fix. the motor is almost like a window motor. inside the gears are bushings that can be replaced. when you remove the gears there is a splined shaft that turns the gear. on the outside of the housing in line with the shaft is an adjustment screw. the left side was tight but did get it out with out touching it and the right was loose. since they worked before i took them out i didn't want to touch them. well the left side worked perfect but right side would only go around halfway. figuring i had nothing to lose, tonight i went in to the shop, loosened the jamb nut and turned the screw in two turns and now the light works perfectly.

to me, service manuals are not what they used to be. i remember if you got the one from the maker of the car, it told you everything about the car. seems now all they do it give you a general rundown and 3/4 of the book is about the computer system. i know the computers run a lot of things in the car but there are still mechanical things that need to be fixed. just my ranting here.

Glad that's all it was, Dave!
The service manuals these days certainly do NOT get into repairing individual components like that. They would rather you(or the dealer) simply replace the component rather than attempt a repair...

 While we are on the subject of headlight motors I have a question to throw out. On my '96 the headlights open and close smoothly but the motors seem to run on for a few seconds each time. I haven't disassembled them yet but wonder what exactly shuts off the motors. The gears must be ok as they work great. I checked another '96 in the Beachcombers Club and his does the same thing. Does anyone have an idea what is causing this? It also occurs when I turn on the parking/fog lamps without rotating the headlamps themselves. Just a clicking for a few seconds.

i believe there is a relay that controls the electric to the headlights. if it does it on another vette, could it be a normal condition or did it just start happening?
i know there is a metal piece that looks like a tee on mine that controls the travel that is on the shaft of the motor.
when i reinstalled the headlights on the car they were not opening right, so that's when i read the directions. to remove the headlights from the car(frame and all), you are supposed to open the headlights and then unplug them and remove. to reinstall they are supposed to be in the open position and then plug them in and they close and work properly.

wonder if yours may need an "adjustment" as if you were installing them completely. by that, i mean unplug the light and open it fully and then plug it in and see what happens. just to be on the safe side i would check the service manual for a 96 and see it the installation procedure is the same BEFORE you try it (if you do decide to).

let us know the outcome of what you do.
eddie208902010-01-12 19:55:22

What may be happening is the rubber/plastic  "bushings" inside the gears have deteriorated, and that's allowing the motors to run a little farther than normal.
The way the motors are, the armature in them will move forward/backward under pressure(as when the headlight are fully open or closed), and when it gets to the end of that small amount of travel, they hit what is basically a small set of points, and that opens the circuit, turning off power flow thru the armature. This is what stops the motors when the headlight are fully rotated open/closed. If the gears are a little worn, or the cushions are broken down into rubber dust, then there isn't enough pressure on the armature to trip the points open at the right time, until the motor turn the gears just a tad farther than "normal".
Maybe I can find a pic that would help make sense of this.

The headlight circuit itself shouldn't have any power with just the running/parking lights on, so there's really no reason for the motors, or the relays to be clicking...unless there is something amiss in the headlight switch, or wiring.

Adams' Apple2010-01-12 21:17:53