Is this why my brake lights go out?

[620doof]

On the drivers side, when I hit the brakes that side goes out completely. But the tail lights and turn signal works fine. I checked the wiring, it looks fine. There's a 4-pin trailer harness but it seems to be wired correctly. I cleaned all the grounds I could find.

 

But while looking for change(for a mc chicken) I found this behind my seat:

 

 

 

The two black wires coming out of the connector are cut, just bear wire.

 

Here's a close up of the wires coming from under the carpet:

 

 

 

Do these have something to do with the brake lights? It looks like it may come off the bundle of wires that runs up the frame rail and then into the cab. Any help would be appreciated!

[datsunaholic]

No, that's the seatbelt switch wires.

 

When you say "that side goes out completely" do you mean the running lights go out on that side, or do you mean the brake lights themselves don't work?

 

 

The running lights go out with the brakes is because the ground isn't hooked up anymore. The lights kind of work (running lights) because it's finding a path through the brake light filaments. When you press the brake pedal it puts 12v to both sides of the bulb, and with no ground that means no voltage difference and hence no lights.

 

If it's just the brake light itself, and the running lights stay lit then it's the turn signal switch on the column (the brake lights feed through it).

[620doof]

No, that's the seatbelt switch wires.

 

When you say "that side goes out completely" do you mean the running lights go out on that side, or do you mean the brake lights themselves don't work?

 

 

The running lights go out with the brakes is because the ground isn't hooked up anymore. The lights kind of work (running lights) because it's finding a path through the brake light filaments. When you press the brake pedal it puts 12v to both sides of the bulb, and with no ground that means no voltage difference and hence no lights.

 

If it's just the brake light itself, and the running lights stay lit then it's the turn signal switch on the column (the brake lights feed through it).

 

Darn, ok. I will have to double check but I'm pretty sure that side just goes dark. No lights at all. I will have my girlfriend help me when shes up to see exactly whats going on. Thank you though.

[Silvester]

No, that's the seatbelt switch wires.

 

When you say "that side goes out completely" do you mean the running lights go out on that side, or do you mean the brake lights themselves don't work?

 

 

The running lights go out with the brakes is because the ground isn't hooked up anymore. The lights kind of work (running lights) because it's finding a path through the brake light filaments. When you press the brake pedal it puts 12v to both sides of the bulb, and with no ground that means no voltage difference and hence no lights.

 

If it's just the brake light itself, and the running lights stay lit then it's the turn signal switch on the column (the brake lights feed through it).

 

Your knowledge is a real attribute to this site. I would definitely would like to meet you someday.

[620doof]

I concur!

[620doof]

Finally got my girlfriend to help me.

 

It actually does NOT go completely out.

 

If the turn signal is going, it stays blinking.

 

If the tail lights are on, the tail lights stay illuminated on that side, but do not brighten when you hit the brakes.

 

So I should inspect the wiring at the turn signal switch then?

[datsunaholic]

Wiring at the switch, or the switch itself. More likely the switch, since if it was the wiring the turn signal wouldn't work either.

 

It's been a couple or 5 years or so since I took one apart, but I had the same symptoms with my '78, and disassembling and cleaning the contacts and the little springs and BBs in the switch fixed it. BUT... be aware, it's got a lot of tiny parts that are critical to it working. And yes, you have to take the steering wheel off to remove the switch. What happened with mine was mostly corrosion and the factory grease had gotten so clumpy and full of dirt the switch wasn't making contact properly when centered. I used dielectic grease (same stuff GM uses on light bulbs from the factory) to regrease it.

[620doof]

Wiring at the switch, or the switch itself. More likely the switch, since if it was the wiring the turn signal wouldn't work either.

 

It's been a couple or 5 years or so since I took one apart, but I had the same symptoms with my '78, and disassembling and cleaning the contacts and the little springs and BBs in the switch fixed it. BUT... be aware, it's got a lot of tiny parts that are critical to it working. And yes, you have to take the steering wheel off to remove the switch. What happened with mine was mostly corrosion and the factory grease had gotten so clumpy and full of dirt the switch wasn't making contact properly when centered. I used dielectic grease (same stuff GM uses on light bulbs from the factory) to regrease it.

 

 

Ahhhh man. So am I going to have to get a steering wheel puller to get the wheel off then i'm guessing? That's a big hassle for some lights! Darn. Oh well, next couple days off I'll try and get to it. Thank you sir!