No brake lights when either blinker is on

[aggiegrad]

My trucks brake lights have always worked (or so I thought). I have had several people following tell me my brake lights dont work but they were always fine when I test them. It has passed the yearly inspection at least 3 times with no problem. I have finally come to realize that the brake lights only work when neither turn signal is on. The turn signals work fine but just keep the brake lights from lighting also. Anybody run into something similar to help track down the issue?

thanks for the help and knowledge.

[MySons68C20]

Sounds like a ground issue to me. I would pull the bulbs, clean the socket, install fresh bulbs and retest. If that doesn't work run a ground wire from the taillight housing to body or frame. I did this and it solved all my taillight, blinker and brake light problems.

[pjmoreland]

Your brake lights do work when the turn signals are off, so that implies you may have good grounds. It could also be a case of gummed up contacts in the turn signal switch inside your steering column.

[72c20customcamper]

^^^^ this mine was doing the same but only when I use the detent . If I just pushed it till it went on the brake lights worked. Changed out the switch well actually the whole column and it’s back to normal

[aggiegrad]

Just wanted to provide a followup. Replaced the turn switch and now the brake lights work all of the time. Thanks for the valuable information.