91 headlight problem

[doctorofpain]

Help please!! 91 Corvette and the right side headlight will not open or close via the switch. Troubleshoot and had power to the motor so I thought the motor was bad, replaced motor and it still does not work. I found a wiring diagram that shows a "headlight door control unit" that runs things via a couple of relays one for each side so now I think this must be it. Does anyone know where this unit is located or may have had this same issue? Did check my old motor once it was removed and of course it works! Any and all help is appreciated.
Thanks
Doc

 

[boomdriver]

Help please!! 91 Corvette and the right side headlight will not open or close via the switch. Troubleshoot and had power to the motor so I thought the motor was bad, replaced motor and it still does not work. I found a wiring diagram that shows a "headlight door control unit" that runs things via a couple of relays one for each side so now I think this must be it. Does anyone know where this unit is located or may have had this same issue? Did check my old motor once it was removed and of course it works! Any and all help is appreciated.
Thanks
Doc

The relay box used to be in the driver side headlite well, small box attached to the wheel well,toward front side of tire. My yr uses 3 relays. I think yours went to 2.

 

[doctorofpain]

thanks I'll go look ---
Doc

 

[vetteoz]

The relay box used to be in the driver side headlite well, small box attached to the wheel well,toward front side of tire. My yr uses 3 relays. I think yours went to 2.

No relays on late models
All solid state electronics in the headlight control module

http://cgi.ebay.com/ebaymotors/Corv...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

 

[muddywaters]

Probably the infamous bushings, I have a control module by the way

 

[doctorofpain]

Thanks for the good info -- so I will do some troubleshooting to make sure I got the right culprit this time and at least it is easy to get to.

 

[boomdriver]

No relays on late models
All solid state electronics in the headlight control module

Corvette 88-96 Headlight control module - eBay (item 300460322313 end time Dec-24-10 17:02:01 PST)

A 91 ?? those are still relay are't they?

 

[doctorofpain]

Did some more t/s and jumped wires from the left side at the module to the right and all works fine, left the wires jumped and both sides work as they should so bad module it is. Thanks for all the advice/help. Will replace module and all will be right again.
Doc

 

[vetteoz]

A 91 ?? those are still relay are't they?

Don't know when the change was
My '87 had the 3 relays and 3 wire motors.
My '89 and '90 had the 2 wire motors with the elec control box
Never worked on a '88
When I gutted the '90 to make into a race car I put the late model headlights into the '87 so I have headlights
that only need the cheap bushes replacing

 

[boomdriver]

Don't know when the change was
My '87 had the 3 relays and 3 wire motors.
My '89 and '90 had the 2 wire motors with the elec control box
Never worked on a '88
When I gutted the '90 to make into a race car I put the late model headlights into the '87 so I have headlights
that only need the cheap bushes replacing

Yep, I knew they progressed from 3 relays eventually to none, but I thought they were using 2 up to LT models, but I could be wrong in the timing of the design changes. Its hard to keep up with what changes happened in which year.

Late model motors...
Thats what I should do...

Was there anything that had to be changed to put the newer model (better) motors in the '87? And,. what were the advantages in which later yrs?

next time, thats what I'll do. I've rebuilt this 87 so many times the screw holes in the motor housing are worn out. I've even got a spare set of nylon gears around here somewhere..But, its time to do something different. I would do the flush mount "contemporary" headlite upgrade but to me, Corvette means flip over headlites and round tailites...
Thanks for the idea !

 

[vetteoz]

Late model motors...
Thats what I should do...

Was there anything that had to be changed to put the newer model (better) motors in the '87? And,. what were the advantages in which later yrs?

Been awhile.
I had everything so I was able to use the stock late model harness and plug from control module to headlights and just adapt the wires from the headlight switch
Have a write up somewhere on how to rework using original wiring
will have to confirm but recall later motors are bolt in replacement on old style mounts

 

[boomdriver]

Been awhile.
I had everything so I was able to use the stock late model harness and plug from control module to headlights and just adapt the wires from the headlight switch
Have a write up somewhere on how to rework using original wiring
will have to confirm but recall later motors are bolt in replacement on old style mounts

Cool !
If you find that write up I'd sure like to see that. Its no emergency, everything works fine today...:eyerole But the next time I need to do gears or motor service I'd like to upgrade. It would be nice to know which motors to look for and what to expect as far as mating to the 87 harness/relays/switch.
Thanks in advance

 

[Schrade]

COMPLETE headlight diags, with pics, wiring schematics, etc., here...

edit:
Oops - some of the pics dropped from the server - gimme' a while here to upload them again...