Wiring gurus please help.. No brake lights.

[briancave]

I've got no brake lights and am totally stumped. Here are the symptoms:
Taillights work fine
Both rear turn signal lights work fine and blink at correct speed so bulbs are OK
Hazzards blink fast and only work on front lights
No brake lights
Brake switch is new and tests fine as in getting 12v power and switching on when brakes applied. No brake lights when bridging brake plug contacts either.

Any help would be much appreciated. Might something be screwed with the column wiring or turn signal switch? I've got to say that of all the cars I have owned, this is the most impossible to see under the dash. My bald spot has increased in size with this problem already.

 

[Viperwolf1]

What year is it?

 

[briancave]

'72 sorry I omitted that. Glad you are online Viperwolf.

 

[DirtDonk]

With the key OFF, flip the turn signal switch to one side or the other and hit the brake pedal again to see if either lamp lights up at that point.
If so, I would have to say it's your switch.
If not, then it could be some column wiring.

At least I think that's a legit test. Wait for Phil to pop back in to confirm.

Paul

 

[Viperwolf1]

Can you measure 12V on both sides of the brake switch? The reason I ask is because there are 2 possibilites and it would narrow them down to one.

 

[briancave]

Thanks Paul,
No dice on the flipper test. Brake lights didn't even flicker.
Viperwolf,
When the brakes are applied there is 12v on both terminals of brake switch.

 

[Viperwolf1]

1) Open brake light circuit in the turn signal switch or column wiring. If this was the case you would still see 12V on both sides of the brake switch when it's on.

2) Short to ground in the brake light wiring between the brake switch, column connector and hazard switch. This fits with the hazard flasher cycling fast. You would not see 12V on both sides of the brake switch when on in this case.

 

[Viperwolf1]

Ok. You have senario #1 along with a bad hazard flasher. It's near the turn flasher and has a black connector. Turn flasher connector is light blue.

 

[briancave]

Viperwolf,
I may have confused things in my answer to the 12v on both terminals of the brake switch question. Without the brake pedal depressed, there is 12v to only one terminal. Pressing the brake correctly ( I think) closes the switch and that's when I can read 12v on both terminals. Am I reading your response correctly in that this would point to option 2?

 

[Viperwolf1]

Viperwolf,
I may have confused things in my answer to the 12v on both terminals of the brake switch question. Without the brake pedal depressed, there is 12v to only one terminal. Pressing the brake correctly ( I think) closes the switch and that's when I can read 12v on both terminals. Am I reading your response correctly in that this would point to option 2?

No. #1 it is.

 

[briancave]

Got it. Thanks so much for the help Viperwolf. This forum is awesome!

 

[briancave]

Phil (viperworf) was 100% correct. Amazing diagnosis. Replaced flasher, hazzards now blinked at correct speed but no brake lights. Replaced turn signal assembly and column wiring. Bingo! Everything works perfectly. Replacement turn signal had a few wire colors that didn't match with stock but figured that out. Thanks Again!

 

[treihesse]

Check your grounds number one I've had to move the switch on the brake pedal a little