91 coupe door lock wiring
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Joined: Dec 2004
Posts: 670
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From: Mitchell SD
91 coupe door lock wiring
I recently bought a '91 coupe and the power lock switches on driver and passenger both weren't working. After studying it for a while I have determined that both lock motors and switches are functioning correctly. I have been able to get both locks to work from the drivers side by grounding the light blue and black with white stripe wires to a known ground on the LH side. If I try that on the passenger side it blows the fuse. The wiring diagram I'm using appears to show that there should be continuity between the light blue wires on driver and passenger switches and the black/white stripe wires on driver and passenger switches and there isn't. The diagram isn't very clear but it looks like there are two connections under the dash C250 and C251 which I suspect might be the lost connection. The car had an aftermarket stereo installed before I bought it which may be when these got disconnected. I can live with it the way I have it hooked up now with locks controled on the driver's side only but it would be nice to make everything work the factory way. Can anyone offer any insight?
Last edited by jabrun; Sep 27, 2014 at 12:16 PM. Reason: spelling
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 42
From: Baltimore, MD USA
This is the schematic for a 90 which uses the same switches as a 91.
If someone installed a keyless entry unit and removed it that could explain why you have no continuity between the Light Blue wires and the Black/White wires that go between the two switches.
A keyless entry installation requires the cutting of the Light Blue wire and the Black wire
(in your case a Black/White wire) and the wires go to the contacts of a relay. The relay is controlled by the keyless entry unit allowing it to lock or unlock the door using a key FOB
or via the normal door lock switches.
If someone installed a keyless entry unit and removed it that could explain why you have no continuity between the Light Blue wires and the Black/White wires that go between the two switches.
A keyless entry installation requires the cutting of the Light Blue wire and the Black wire
(in your case a Black/White wire) and the wires go to the contacts of a relay. The relay is controlled by the keyless entry unit allowing it to lock or unlock the door using a key FOB
or via the normal door lock switches.
Last edited by Hooked on Vettes; Sep 27, 2014 at 01:08 PM.
