Deepa

All,

My courtesy lights on my 91 have stuck on. If i remember right, I hit a bump and the lights came on and stayed on. I am aware of the door ajar switches and their adjustable plunger, etc. I looked for codes and i have H25 for the CCM which means theres an issue with the circuit. Scanning the 1.3 module, I was able to verify that both the passenger and driver door ajar switches are working correctly.

What is my next step? I am having trouble getting one bolt out of the headlight switch, the one near headlight bezel is being a bitch. What size is the hex head?

I'm going to buy a relay and swap it out, which I am assuming is under the passenger side kick panel near the aux fuse panel.

Any other ideas? I've read that if the keys are not straight up and down in the lock cylinders the lights will stay on, but they both checked out ok.

I have the fuse pulled at the moment because my battery would die, and I also broke the face of the headlight switch trying to get that bolt out. I am at my wits end and I'm looking for a new angle at the issue.

If you have a 91 gray/Orange headlight switch, im interested.

Thanks,

Mike

Deepa

Update,

The relay is fine...swapped it with the fog light relay and all is ok on that front. When I pulled the relay, the lights stayed on still. The only way the lights go off is if the fuse is unplugged.

Any help would be appreciated. Still cannot get that one last bolt out of the headlight switch to unplug the connector and see if it turns off.

Thanks

Mike

Deepa

Another Update...

Got the switch unplugged, lights still on. Unplugged the relay, lights still on. The FSM Says repair CKT 156 which I am lost about.

The H25 code is in history, so could that still be messing with me now? I still need to check out the key switches but am unsure of how to do that. I need a test light.

Thanks,

Mike

1985 Corvette

If I remember there are two switches per door. One near where the door hinges are and one back near where the door latches. The only thing I can think of outside of that is the courtesy delay timer may have been jarred too bad? If the wiring is still like the earlier C4s, it's on the passenger side of the dash harness close behind the fuse panel. Not sure if one of those going bad or rattled would keep lights on though.

w4egv

My 91 has the same problem even after replacing the door switches. Next i'll change out the delay timer if I can find one....

Deepa

So I was able to test the drivers key switch and door ajar switch and they both checked out fine. I am at a loss at this point. Also, there is only one door ajar switch on my 91. The courtesy lights are controlled by either the ccm when the doors are opened or by the interior light switch. There is not a delay timer on my 91.

I have my drivers door pulled apart looking for a wiring break but I have no idea what exactly ckt 156 is.

Any help would be much appreciated.

Mike

w4egv

no wonder I can't find one LOL..Hopefully someone can find a cure...Not to big a deal for me as I don't drive at night that often. But my OCD reminds me there is something needs to be fixed. I guess i'm lucky as this is the only problem I have with the car..

Hooked on Vettes

If you're positive you pulled the correct relay (Courtesy Lamp Relay) and the interior courtesy lamps stay on, one of the White wires on circuit 156 which consists of 8 White wires spliced together at S232 located LH side behind Glove box area is grounded.

For a coupe.

Circuit 156 White wire goes to these items.

Two Door panel courtesy lamps.
Two Foot well lamps.
Two cargo lamps.
Headlight Switch.
Rear view mirror courtesy lamp bulb.
The Courtesy lamp relay socket.
Spare tire lamp.
Diode module located under the foam where the hatch release solenoid is. (Not used for a convertible).

Most likely the White wire is exposed to something sharp and has cut into the wire which is now providing a ground path for the courtesy lights.

Move the White wire around at its different locations and see if that removes the ground.

It can't be the door ajar switches, the door key switches or its wiring. You've eliminated the headlight switch but not the White wire that goes to the headlight switch
nor the White wire that goes to the Courtesy Lamp Relay.

Look carefully at the wiring at the spare tire lamp, behind the two door panel courtesy lamps
and the rear view mirror wiring which runs in the windshield header channel.

Deepa

I did pull the correct relay and even swapped it with the fog light relay where it worked correctly. I am not looking forward to finding this electrical gremlin but I'll try to start later on today.

Member pmihaltian had this same problem and he ended up replacing the courtesy light delay time relay which is up under the heater core area. I am wondering if this could also be an issue, but I cannot find that part in the electrical diagrams. He also has a 1991 coupe.

If the white wire is broken somewhere, wouldn't that particular light not work correctly? All of the lights work when they are on. Also, I have one of those auto dimming rear view mirrors, so I was in there last summer to install that...

Thanks for all of your help.

Mike

WVZR-1

That is where I believe that you'd want to start. Do you remember what you did to accomplish that install?

Deepa

it was a very straightforward plug and play install...no splicing of wires, etc. I just had to drop that header trim but I suppose a wire might have been pinched in the process? It's pretty hot here right now, I'll head out once it cools off and give it a shot. Its just hard because so much of the interior is pulled apart...door panels, instrument bezel, kick panels, etc. Its a pain in the rear.

Mike

Deepa

Ok so I made some progress.

When I tap/hit the windshield header, the lights went off. I took off the visors and the interior trim near the mirror and have isolated the general area of the wiring issue, but have not exactly found the break yet. Should I just throw a wrap of tape around the harness or do you think the individual white wire is rubbing against another bare wire in the winshield header?

Once I took the trim off, I cannot replicate the problem. Ive tried squeezing wires, etc and they just wont short out. It may have been a wire in the modified harness that came with the mirror, so i will make sure those wires are all taped up nicely. There was one tiny bare spot on the white wire in the mirror harness but there was not anything for it to touch to ground it out. The header is painted/coated with something and you need to be down to bare metal to ground out, which I why I think the wires are touching another one in the harness somewhere on the passenger side of the header.

So finally progress is being made and you guys are always right on the money.

Thanks,

Mike

Hooked on Vettes

The Courtesy lamps in your 91 are controlled by the CCM via the Courtesy lamp relay or by manually using the headlight switch.

There is no other module that controls them.

You are not looking for a break in the wire. The White wire has a bare spot that is some how getting a ground path back to the battery.
It's either from the car body or another wire which is a ground wire.

That is not likely because the only ground wire in that area is a Black wire for the Lighted Vanity Mirrors. The chances of both wires having the wire insulation worn off at the same spot and then the two bare wires contacting each other is

Either your new mirror is causing the problem (unplug it) or you pierced the White wire with one of the trim screws or pinched the wire when you replaced the trim.

If you can't find or access the area of the wire that is causing the problem the only permanent solution is to cut both ends of the White wire and run a new one.

Find the White wire at the Courtesy Lamp Relay socket and follow it to Splice 232. At splice 232 will be 8 White wires.

At the splice, cut the White wire that goes up the Passenger side A pillar. Tape a new replacement wire to it and pull it up the A pillar.

This is the schematic for a 90 which shows the splice. A 91 should be similar.

Deepa

I completely agree about the break having to hit a screw or the header. I just cant find any breaks in the electrical tape which match up with areas where the paint is gone off of the header (only 2 small spots).

Also, the screws go into the header to hold the trim up, but the wiring runs on the windshield side of the header, so there is not any way those screws would have pinched anything.

I am going to look harder today for any issues, but I plan on running without the trim installed on the header for a few weeks and see if the problem reappears. I do not think the actual mirror light circuit is faluty, the map lights work fine and i cannot get the problem to replicate with the mirror plugged in or unplugged. The issue I saw was in the wiring harness for the new mirror, but it did not have anything to come in contact with which was metal unless it was somehow pinched by the new mirror mount.

Thanks for all of your help. I am hoping to avoid running a new wire at this point. I cant wait to get the car back together and start driving as this is definately vette weather.

Mike

Deepa

Just an update...Lights are staying off and working well. Taped up a few questionable areas in the windshield header and no issues thus far.

Thanks for all of your help. You guys are the best.

Mike

24yrold&86conv

Was you issue with all the interior lights? I am having an issue with just my cargo lights staying on. I did the ccm check 1.3 and both doors and hatch sensor/plunger works. I think I am going to try relacing the relay, but how do I get to it? I have the interior under the glove compartment apart and can see the relays but cant figure out how to get to it. Does the ac vents come off somehow?

I have a 1991 coupe.