Dim Brake Lights, Go out with headlights on

[blackbronco92]

Hey guys. My '87 Pickup developed an electrical issue when I took it upnorth for hunting.

On the way up everything was fine. I took it out into a couple of trails and dirt roads and jiggled some things up, I'm sure, and I assume I've got maybe a bad ground somewhere.

The brake lights are very dim when the brake is applied. If the parking lights or headlights are on, I've got no brake lights at all. Turn signals work in the front and rear of the truck, but same rules apply. In the rear, they are dim or non-op with lights on. The hazard lights have been screwy for years, so I'm not sure if that is related or not, but when the hazard switch is pressed, they'll flash slowly and increase in speed until they are flashing extremely rapidly, but again I've had that issue for some time now.

I've checked all the fuses in the truck and I'm good there.

I pulled both rear lenses and housings out and inspected wiring... It's old but connections look good.

Can anyone give me an idea what might cause these symptoms? I'm assuming I've got a bad ground or a short, but since the headlights affect the brake light operation, I'm thinking somewhere in the front of the truck rather than the rear...

Thanks for any help provided.
Aaron

 

[Greenlee]

I have a stepside bed and I had the exact same symptoms after I replaced the bed wood and put rubber pads between the bed and frame. I suddenly had no brake lights with the headlights on and they were dim with the headlights off. I put a ground strap from the bed to the frame near the tail lights and that fixed it.

 

[imiceman44]

Hey guys. My '87 Pickup developed an electrical issue when I took it upnorth for hunting.

On the way up everything was fine. I took it out into a couple of trails and dirt roads and jiggled some things up, I'm sure, and I assume I've got maybe a bad ground somewhere.

The brake lights are very dim when the brake is applied. If the parking lights or headlights are on, I've got no brake lights at all. Turn signals work in the front and rear of the truck, but same rules apply. In the rear, they are dim or non-op with lights on. The hazard lights have been screwy for years, so I'm not sure if that is related or not, but when the hazard switch is pressed, they'll flash slowly and increase in speed until they are flashing extremely rapidly, but again I've had that issue for some time now.

I've checked all the fuses in the truck and I'm good there.

I pulled both rear lenses and housings out and inspected wiring... It's old but connections look good.

Can anyone give me an idea what might cause these symptoms? I'm assuming I've got a bad ground or a short, but since the headlights affect the brake light operation, I'm thinking somewhere in the front of the truck rather than the rear...

Thanks for any help provided.
Aaron

It's a ground.
Most likely in the back.

 

[nitro_rat]

It's a ground.
Most likely in the back.

X2!

 

[toomany]

Went through the same thing with my K5 recently. Cleaned up the grounds and put all new sockets in (they looked rough) and the problem went away. Was probably the ground.

 

[sweetk30]

left rear tail light lens and backer out . there ishe factory ground attachment point.

just did one the other day on my truck/trailer I got.