My right headlight will go up but won't retract. Any ideas?
Thanks Larry

 

http://members.shaw.ca/dankai/Headlight%20Doors.pdf

 

Per Agent 86's wiring diagram. If you uplug the headlight motor plug from the engine wiring harness and check the voltage on the engine side of the wiring harness you should have 12V across 2 of the 3 terminals when the light switch is turned on. When you turn the lights off you get 12V between the remaining terminal and one of the terminals you first got 12V from but the polarity is reversed. If the voltage is ok then the relays are working. Test it several times to make sure it's not the relays. If you set your meter to ohms then you should get some continuity in the headlight motor harness between 2 of the 3 wires. Depending on whether the headlight is in the up or down position there should always be continuity between 2 of the 3 wires. If there is no continuity between any of the wires then there is a problem in the motor. If you turn the manual **** one way or the other and you suddenly get continuity then it's in the contact points of the limit switches or in the brushes. There are no replacement parts for these motors. Usually, they can be dismantled and cleaned up which might give you some more time on them but they eventually wear out. The early motors are not the same as the later motors inside. After plugging everything back together and you turn your lights off and the headlight won't go down try turning the manual **** on the headlight motor. If the headlight suddenly starts to rotate to the closed position your problem is probably in the motor limit switches or brushes. This is from my experience, maybe someone else will chime in.

Art

 

Something else to remember about the wiring schematic. In the motor, the limit switch contacts do not connect until the motor rotates and stops. In other words when you turn the headlights to the on position the limit switch contact in the motor assembly remains in the "closed" position until the headlight completely opens and stops. The contacts for the "open" position then make contact. The same thing is true when you turn the headlights off, the contacts remain connected in the "open" position until the headlight rotates and stops. When the motor stops the contacts in the motor now connect in the "closed" position. Keep that in mind when you are looking at the schematic trying to figure out how the current flows in the motors. The headlight relays and isolation relay are different. When you turn the lights on the headlight relays move immediatley to the open position. When you turn the headlights off the relays move immediately to the closed position. Hope this makes sense.

Art

 

Thanks for the help. Will check it this weekend.
Larry

 

I've got an 86 too. Last year I had my passenger side headlight motor apart so many times I could do it in my sleep and I never could fix the stupid thing. Mine would close but not open.

I changed all the relays and tested all the voltages and finally realized I was in over my head. I then sent it off to CorvetteCentral who repaired it for about $100

GM has no parts for it and the Chevy Parts guy "recommended" I upgrade to the 88 and later system, to the tune of about $600!!

I took a pass on that recommendation.

Jake

 

just a note: the headlight motors can be rewired from three wire relay system into a 2 wire module control system. this replaces all the relays and the motors must be modified by removing the third control
wire. then the new control module is wired into the existing system. the module could be used and found at auto slavage places, for about 20 bucks,, this module is the same at 87-89 firebirds and transam, with lite doors.. the motors can also be used to retrofit c4's..
i couldn't attach files to this post , do a search , you will find