1972 FJ40 Brake Lights Not Working Help (1 Viewer)

[Fj40surfer]

Hi, when I push the brake pedal both turn signal dash lights come on but the brake lights do not. The tail lights work and both rear turn signal flashers work and the lights flash when the hazards are pulled on. I’ve tested the bulbs and they are ok. The wiring from the firewall back is all new from
Coolerman and has power and good grounds since everything else works as it should.

It looks like from older threads that grounds can be a problem but I have a really good ground for the harness and at each combo light, plus the turn signal flashers and taillights work. I am stumped and would appreciate any thoughts? Seems like since the dash lights come on that has something to do with it? I also noticed that when the tail lights are on and the brake pedal is depressed the bulb dims for a second right when the brake is depressed? Thanks.

 

[locklaw]

Sounds like you have the input wires from the brake master (GW) and turn flasher (GL) swopped around at one of the turn signal switch blocks going to the lever. Check your connections from the brake switch and you should find how you are powering dash lights instead of the brake lights.

 

[Fj40surfer]

Sounds like you have the input wires from the brake master (GW) and turn flasher (GL) swopped around at one of the turn signal switch blocks going to the lever. Check your connections from the brake switch and you should find how you are powering dash lights instead of the brake lights.

Thank you I will give this a try.

 

[45Dougal]

I've just fixed a similar fault caused by a broken track on the back of the instrument cluster (the GND on the backlighting bulb) causing the indicator dash lights to come on with the side lights, grounding the backlighting backwards through both dash flashers and forwards through all external flasher bulbs - not sure how your brake switch could light that up though unless if was crossed with your tail light also??

 

[Fj40surfer]

I've just fixed a similar fault caused by a broken track on the back of the instrument cluster (the GND on the backlighting bulb) causing the indicator dash lights to come on with the side lights, grounding the backlighting backwards through both dash flashers and forwards through all external flasher bulbs - not sure how your brake switch could light that up though unless if was crossed with your tail light also??

Finally figured this out yesterday. I unplugged the turn signal switch under the dash and the brake lights came on but the day indicators did not so it had to be the turn signal. I had replaced the turn signal assembly last year since the old one didn’t flash on one side. I plugged in the old turn signal and both sides worked. So I wound up putting the old turn signal switch into the new turn signal assembly and everything works now.

I’m not sure why the new turn signal wiring wasn’t working but it may have been as simple as the fact that the wiring on the new turn signal assembly was about 2” shorter than the old one and it just barely could reach the plug under the dash. Maybe one of the connections inside the plug wasn’t making a clean connection and that was causing the issue. Something to check for anyone having a similar issue. Thanks for responding.

 

[45Dougal]

Great to hear that you got it fixed. I only have indicators and horn on the column, so I don't know how your brake light got involved up there.
Hope it stays fixed

 

[locklaw]

Great to hear that you got it fixed. I only have indicators and horn on the column, so I don't know how your brake light got involved up there.
Hope it stays fixed

Indicators and brake lights run through the turn signal switch on US and other models so that the turn cancels the brake light on the side the indicator is on.

 

[Fj40surfer]

Indicators and brake lights run through the turn signal switch on US and other models so that the turn cancels the brake light on the side the indicator is on.

Thanks 45Dougal, your comment got me in the right direction to fix it.