denver88carrera

I am stumped and after searching old posts am hoping someone might be able to help. When my headlights are on, both tail lights in the driver's (left) side cluster are dark (both lamps on right side work). When I hit the brakes, the brake lamps all work fine. After finding no power at the connector in the taillight cluster when the tail lights should be on, I pulled fuse 40 and checked there. Nothing. 41 (passenger/right side tail light) has 12v+. Ground is good at the fuse box, and the bulbs all look good (and I've swapped in some spares).

Can anyone suggest what I'm missing? I do not have a good wiring diagram so am working a bit in the dark (no pun). I don't think this is related, but when I started this troubleshooting my brake lights were also not working. Cleaning the ground on the left side of the engine bay rectified this problem. Car is an 80k mile 1992 C2 Coupe that is in otherwise excellent shape.

Thank you for your help!

-nick

Here's the lighting diagram for the '91. I don't think there were any lighting changes for '92. The ground is shared with the brake light, so if that works then the ground is okay. Pretty unusual for that ground point to get dirty/corroded enough to cause any problems though. That would make me wonder about other electrical contact corrosion issues and the tail light sockets.

It's a really simple circuit. If the front side marker works, then the fault is between the brown/black wire that feeds +12v to the rear tail light and ground.

Left tail light connector:
Pin1 is +12v for the side marker lights
Pin2 is +12v from the brake light circuit
Pin3 is ground for all
Pin4 is +12v for the turn signal

Edit- sounds like you may not have 12v at fuse #40? So front side marker doesn't work either? In that case, I would bet the headlight switch is the culprit. It has a dedicated output for each side. The switch can be pulled apart and you can clean the contacts, but beware of tiny ball bearings and springs!

denver88carrera

Thank you Nick! This is exactly what I needed to know. The headlight switch has always felt odd to me, so I would not be suprised to find that is where the problem is. I appreciate the warning about pulling it apart! I'll give that a shot and then order a new one if I cannot get it testing right. Thank you for the diagram as well.

denver88carrera

How does one get the headlight switch out? I was able to remove the **** (by pulling straight out--hard), and removed the 4-hole bezel by inserting a dental pick into one hole and spinning it counter clockwise a couple of times. The switch is now loose in the dash, but after maneuvering myself on my back under the dash, all I can see is a big VDO box between me and the switch (and no obvious way to pull this box). Do I need to remove the lower dash pad or is there an easier way? Thanks!

denver88carrera

Update: I was able to remove the VDO box (two 10mm plastic nuts and then two levers on the plugs) and (barely) got the switch out. I don't know if the switch is bad, but I do know the gray and red wire broken off the back of it isn't a good thing. Can anyone tell me how to pull the pin from this plug so I can repair it? I will have to pull my driver's seat tonight to get better access as I hardly fit in the footwell and cannot get a good look at it currently, much less do a repair. Thank you!

denver88carrera

A quick follow-up on this for the benefit of those using Search in the future:

Nick's tip to check the headlight switch was my first key step (thank you again Nick!), and the second was a $12 set of terminal removal tools. I bought one of many look-alike sets from Amazon (mine was the MENKEY Terminal Removal Tool Kit for Car, 39 Pieces Wire Connector Pin Release Key Extractor Tools Set for Most Connector Terminal). The tool that was essentially a 2mm round hollow tube fit over the broken wire, pushed into the backside of the connector, and with a satisfying "click" released the wire and pin from the connector. It was a quick soldering job on the bench to replace the torn stub with a new wire with enough length to allow me to re-attach it to the other broken end. The repaired pin and wire clicked solidly back into place without a tool after the soldering job. I have no idea how I'd have solved this without the terminal release tool. Anyhow, with the wire repaired, everything works. The secret to avoiding this issue in the first place is to make sure that odd little plastic bezel on the headlight **** is tight so your headlight switch body doesn't turn when the **** is twisted.

-nick

Awesome! Good tip on the making sure the twist isn’t loose and constantly wriggling the wires- and on getting a good pin/connector release tool. I’m always swearing every time I use mine.