So I just bought a 06 f650 rollback. Brake lights rarely work but sometimes when you fully depress brake pedal they work and then they go on and off. Left turn signal works sometimes and when it does they are very dim. Front left turn signal always works fine but the rear does not. Right turn works like they should. Tried replacing brake switch attached to brake pedal. Help please

 

It sounds like it's most likely a wire shorting out somewhere. Could possibly be a pinched wire as well.

 

Brake light power goes through the turn signal switch. One to watch the lights and one to wiggle, push, and pull on the switch. If the lights come and go replace the switch.

 

Follow the harness that runs along the left frame rail. Ahead of the rear axle there should be a grey plastic connector for the rear lights and ABS circuits. I have had trouble with those connectors, they are not very water-tight. Both rear light and ABS problems.

 

That's what I thought. I remember reading that somewhere but my dad disagreed. Ordered one last night just in case. Thanks for the lead

Should the abs light be on? Haven't seen abs light on yet. Although one time when I started it to move it there was a brake light on with a lightning bolt and there was a constant chime. After turning truck off and back on I haven't seen it since. Is this connector connected into the box where all the brake lines come out of? It's right behind the cab.

I sure hope not. I hate tracking down shorts. Tracked down the wires coming from the lights to the big junction box in the rear passenger side and didn't see anything out of the ordinary

 

Figured it out. Whoever owned it before me didn't have a cover on fuse box so the contacts on one of the fuses was covered in dirt. Now I gotta take out all the fuses and clean the contacts. Thanks guys

 

Glad to hear it was an easy fix.