I have a 72 Olds 442. When i connect my battery, the interior lights, fog lights, and brake lights tend to stay on even with the light switch off, and no foot on the brake pedal. The interior lights doesn't dim either when I try to dim them. I'm guessing its in the light switch. What could be the problem?

 

Are you sure it's the brake lights, or is it the tail lights (the ones that should go on when you turn on the headlight switch)?

I had a similar problem with my '67 Delta 88 (taillights always on whenever the ignition was on), and it turned out to be an incorrectly wired underhood light. The power connector for the hood light was connected to something it shouldn't have been, and power was feeding back through that line to the taillight wiring.

Brake lights or taillights, though, more likely than incorrect wiring or a bad switch is a bad ground. Thoroughly check the grounds on each light. I have found that about 99% of electrical problems are due to a poor or missing ground connection.

 

I disconnected the light switch from the Pigtail just to see if it has anything to do with the switch. It seems as though I will have to check my wiring for the lights.

As I turn the light switch i get nothing. Head lights work fine. It is the tail lights, fog lights and interior lights that stay on. I've disconnected my fog lights under the hood.

 

Sounds like a major short to me... Check for wiring hacks under the dash or under the hood. If fog lights or alarm system was installed, check them too - disconnect them and see if the problem goes away. Could be the light switch, but check for obvious stuff first.

 

I've disconnected the fog lights and the tail lights and dash lights are still on. I've also disconnected the head lights, changed the light switch, and dimmer switch.

 

Try pulling out the TAIL fuse and the INST LPS fuse (the little one) and let me know what happens. It will help us track down that nasty short...

 

I pulled out the Tail fuse and the Inst LPS fuse. Tail lights went off when I pulled the LPS fuse, but the dash lights remained on.

 

I'm pretty sure you have a short or other form of incorrect wiring somewhere. The TAIL fuse is in series with the headlight switch and the INST LPS fuse in the order BATTERY --> TAIL fuse --> headlight switch --> INST LPS fuse --> dash lights, so pulling out the TAIL fuse should automatically kill the dash lights as no current should be able to get to the INST LPS fuse. The fact that it does suggests possibly a short in the headlight switch as there is another power lead to the switch for the headlights themselves, and a short in the switch could be allowing power from that lead to leak to the dash light circuit.

If you have not yet done so, I would next get a new headlight switch and put that in. That could be the source of your problems. A new headlight switch is readily available for about $15 at most any auto parts store. Autozone shows them on their website for a '72 Cutlass at $14.99 and "normally stocked at your local store," so you don't even have to order it. Go get one tomorrow and put it in and let us know what happens.

 

I replaced the headlight switch, both door jam switches, and the floor mounted dimmer switch. One thing I did notice is that, there was one only one wire going to the door jam switch(a light color wire, doesn't look like a ground) and then there is a black wire(which I think is a ground) and a light color that goes to the door jam switch on the drivers side. Could this be an issue? The only other thing I've just though of, is a short or bad ground to the dash light switch which I've completely disconnected.

 

When I got my '73 Delta (same lighting circuits and switch), the headlights came on at half-brightness whenever the light switch was placed in the Parking Light position.
Obviously, this was not good.

I initially thought it was the switch. I had a new one on the shelf (got it for a buck at a flea market) and put it in, and the problem seemed to go away.

While I had the dash apart, though, I noticed that the wiring didn't look too good, so I looked further, and I found that the harness had overheated and melted the insulation about a foot from the light switch, and the instrument panel light output (dark green) was melted bare right next to the headlight output (also bare). The instrument light circuit was feeding the headlights through the instrument panel dimmer when the lights were set at Park (and the headlights were back-feeding the panel lights when set to Headlights, defeating the ability to dim the panel lights). When I moved things around to change the switch, they moved out of contact with one another, making it look like the headlight switch change had fixed the problem.

I taped over the bare bits, inspected to be sure the rest of the wiring was okay, and all was good.

Moral of the story: Look around - the problem could be something you don't expect.

- Eric