Bret Ashby

Last night after putting my 71 442 up for the evening I noticed the interior lights stayed on. The door switches on both sides are working as I notice the light dim. But they are not shuutting off. Any ideas or suggestion? For now I pulled the battery cable off.

joe_padavano

Did you verify that the headlight switch **** is not turned all the way counterclockwise?

Bret Ashby

Yes. I read that maybe the connectors on the light switch could have corrosion, or that maybe fuses in the box could have corrosion as well. I just don't know anything about wiring or anything electrical.

joe_padavano

Well, now's a good time to learn...

The dome light is about the simplest circuit in the car. There are two wires running to the dome light, orange and white. The orange wire is powered at all times. The white wire provides ground to complete the circuit and illuminate the bulb. The white wire runs to the pin switches in the door jambs, which are spring loaded to provide a path to body ground when the doors are open. The white wire also runs to the headlight switch. When you turn the **** all the way CCW, a set of contacts close and also provide a path to ground to turn the light on.

If the light stays on all the time, you have a short to ground somewhere in the white wire. This can be caused by the headlight switch being in the fully CCW position. It can be caused by an internal short in one of the pin switches if the insulator sleeve between the pin and the housing has worn. It can also be caused by any pinched or knicked spot anywhere in the white wire.

Bret Ashby

Thanks Joe. Very good information.

joe_padavano

I would also suggest that you pull the lens off the dome light and look at the bulb and contacts. I've had cars where there was overheating of the plastic housing and that allowed the contact in the housing to ground out on the underside of the roof structure. If nothing else, you can simply pull the bulb out until you fix this, so you don't have to disconnect the battery every time.

Bret Ashby

Well I had already pulled the dome light after an incident last week where it did not go off. But now the under dash light are staying on. I definitely dont want to just start pulling all the bulbs.

joe_padavano

You didn't mention that you had the optional courtesy lights under the dash. In any case, they are on the same circuit and have the same orange and white wires. The problem is still a short somewhere on the white wire.

ragz442

I had the same issue with my '76 shortly after completing resto, don't know if '71 is the same or not though. In the process of diagnosing the cause I noticed my console light was not working, also glove box and floods. The fuse was blown, replaced fuse (I believe it was labeled courtesy) and dome/footwell lights were no longer staying on. The fuse hasn't blown since??

joe_padavano

No, you didn't. The OP's problem is that the lights don't turn off.

ragz442

Same issue, dome light and foot well lights staying on. Would dim when pushing in pin switches or turning HL switch ****. Blown courtesy lamp fuse was the cause. This fuse was directly above dome lamp fuse IIRC.

oldcutlass

It could not be the fuse if they were staying on. The dome/courtesy light circuit has a continuous 12v feed to the lamps and are turned on and off by a switched grounds. So as Joe said your issue was different and the fuse replacement was non related coincidental fix.

ragz442

I found it odd that the blown CL fuse corrected the dome lights staying on, thought for sure I had an inadvertent ground somewhere.

joe_padavano

You recall incorrectly. There is only one fuse that powers the dome light, courtesy lights, glove box light, trunk light, map light, clock, and cigarette lighter. It is the 25A fuse labeled "CLK-LTR-CTSY". This fuse feeds the orange wire that powers all of those items. Again, if the lights come on, this fuse is good and the orange wire (power side of the circuit) is good. The only way for the dome light and courtesy lights to stay on is for there to be a short in the white wire on the ground side. Spend some time looking at the wiring diagram in the CSM.

ragz442

Joe, my reply to this thread was not intended to cause a debate, just what I found. I stated "don't know if '71 is the same or not".....obviously not because '76 has a separate dome lamp fuse.

joe_padavano

In your case, separate fuses powering a common system like the courtesy lights CAN cause the problem you saw when one burns out. The circuit can backfeed through the filaments of the other system. This is similar to the problem when there is a bad ground on an 1157 bulb socket and the turn signals work with the headlights off but not with them on. In the case of the OP's 71, the circuit is different and your experience does not apply.