Brake Light Wiring Issue

[babailey]

I have a brake light problem. The brake lights and the turn indicators all work fine when the lights are off. However, with the head lights on, the brake lights do not work at all. This truck was rewired before I purchased it, so it has an aftermarket wiring harness in it and the original light switch is gone (been replaced with a typical two position switch). I suspect there is a wiring issue, anyone have any pointers or lessons learned?

Thanks!

 

[Bobby 57]

i'm gonna ask a dumb question here but when it comes to elecricity anything is possible.when the headlights are on are they on low beam ? turn the high beams on then check the brake lights . if the brake lights work you need to change the power source brake light circuit.basicly you'll need to do this anyway ,but its always nice to find the problem before fixing it.
good luck.
bobby

 

[bigtimjamestown]

I have a brake light problem. The brake lights and the turn indicators all work fine when the lights are off. However, with the head lights on, the brake lights do not work at all. This truck was rewired before I purchased it, so it has an aftermarket wiring harness in it and the original light switch is gone (been replaced with a typical two position switch). I suspect there is a wiring issue, anyone have any pointers or lessons learned?

Thanks!

Your 12V power source to the brake light switch should come directly from the fuse panel. Use a test light and go to the fuse panel with the ignition key "off " and find a terminal that lights up and that's where you want to connect the power source to the brake switch. Sounds like right now it's connected to your headlight switch. You might also try moving the wire on the headlight switch to another terminal on the switch, one that has a constant 12 V all the time with the switch on or off but the brake lights should be fused to prevent shorts. I hope this helps....Big Tim

 

[vwnate1]

I'd also be checking the grounding of both taillights .

 

[babailey]

i'm gonna ask a dumb question here but when it comes to elecricity anything is possible.when the headlights are on are they on low beam ? turn the high beams on then check the brake lights . if the brake lights work you need to change the power source brake light circuit.basicly you'll need to do this anyway ,but its always nice to find the problem before fixing it.
good luck.
bobby

No such thing as a dumb question, especially when dealing with a dumb guy like me!

Good point about the high/low beam, I will check that this weekend. Since I did not do the wiring, I do not know where it all is or how it was done. I need to spend some quality time tracing the wiring out but it is so hot here, I have a hard time getting excited about this.

 

[samsimone52]

Wiring issue

I just had the exact same problem on my 1957. I found that the light needed an additional ground wire installed. Once I did that my rear brake and turn signals worked perfect.

 

[vwnate1]

Well ?

Dija ever look at this ? .

The symptoms you described tend to look more like a simple grounding issue than any need to trace wiring etc. ~ remember : always , ALWAYS K.I.S.S. ! .

Begin by taking the taillight lenses off and testing there , it's dead simple .