Mysterious Brake Light Issue

[Thrashingrage]

Hi all. For the past few month's the rear brake lights on my '90 Bronco II have been acting a bit strange. It seems that they will work intermittently; one day, they will both work fine; the next, the left light will be out. Then, the right will go out for a while, then they will be fine again, and so on. Me and my dad replaced both of the bulb sockets, thinking that they may have been corroded. However, even after this, the lights have been acting funny. Has anyone else had this problem? Is this likely due to a bad ground/messed up wire, or could the switch at the pedal be the cause? I would think if the switch was bad, neither light would work. However, only one light ever goes out at a time, so it's a mystery to me. Any help is greatly appreciated.
Thanks,
Josh

 

[martin]

The problem is in the turn signal switch.

 

[UrbanRedneckKid]

The problem is in the turn signal switch.

Yup. What he said. The multifunction switch splits the brake lights to have a left and right signal. Sounds like the contacts in your are wore out.

 

[Thrashingrage]

Thanks guys. Take it I need a whole new lever assembly, or can I take it out, clean and fix it, and put it back in?

 

[Tedybear]

Might be best served to just replace the entire unit. When contacts start to pit and go bad? It's more worse of a headache removing and reinstalling the part...sometimes several times..

S-

 

[4x4junkie]

I was able to repair the multifunction switch on mine (left brake light intermittent).

This was maybe 5 years ago, so a little foggy on exactly what I did, but I recall it was something like bending or slightly repositioning one of the contacts inside it, or maybe it was grinding a tiny bit of plastic away so the contacts would meet up sooner in a worn spot (or both). Then add a small bit of contact grease in there so it doesn't continue wearing as fast.

If you're good with small electromechanical stuff like this, I don't think it would be hard to figure out what exactly it's doing (or not doing).

 

[Thrashingrage]

Aight, thanks guys. I'll pull that lever out of there one of these days when I don't have school work to catch up on and let you know what I come up with. Thanks for the help!
Josh

 

[90longbed]

had the same issue with my K5 blazer about 4 or 5 years ago.... it was the turn signal/multi function switch..... I know its a chevy, but its pretty much the same setup

 

[Thrashingrage]

Thanks for all of the help guys. I finally got a new lever and, knock on wood, I think the brake lights work consistently again. I found out when I took the old one off that some of the wires that slide into the gray plastic connectors were loose, for what that's worth, though I don't think that they had anything to do with the brakes. Also, it looks like the turn signal lever is a serviceable part, so I'm going to take my old one apart and look at the inside to try to figure out what wore out. For anyone who would just assume fix an old one, they have a bunch of tamper-proof torx screws on them, the ones that you need to use bits with holes in the center of 'em to take off. Anyway, thanks again for the help and I hope that this thread can help someone else out down the line.
Josh