The Stovebolt Site Forums The Shop Area The Electrical Bay Brake light Blues - 1964 C10

Hello I need help! lol I'm restoring my dads ole '64 C10 . I have an issue and really 'Im usually good with electrical. Okay here we go. I have tail lights, blinkers but no brake lights. The switch is good I have 12.48 volts at the rear Yellow and green wire. When I hook up the 3 prong plug going to the tail light I have nothing. I have cleaned the bulb sockets and I have good ground for blinkers or tail lights (running) wouldn't work . I am lost.

Someone will be along soon to give you some advice.

Hy DKMcGee, welcome, the feed from the brake light switch goes through the turn signal switch, we know the turn signals work, so I would check to make sure the feed from the brake light switch is making it to the turn signal switch. The same filament in the bulbs is the turn signal and the brake light when the signals are not activated, hope that helps.

3B has it right. The white wire attached to the brake light switch feeds into the turn signal switch.

Check for 12v at the turn signal switch end of the white wire when the brake pedal is pushed.
If no 12v, fix the wire. If you have 12v fix or replace the turn signal switch.

Here is a partial wiring diagram showing the brake light and turn signal circuits for your 64.

Hello from East Texas: I got problems No brake lights! I pull the bulb get volt meter positive on the right terminal in socket ground on socket wall get 12.8v when brake is engaged . Made a test light same as volt meter nothing with same prosses. Tried several bulbs nothing. Even made 2 grounds soldered to out side of socket on each light grounded to the same ground as plate light Nothing. Running lights work fine as well as both blinkers. I have cleaned up the sockets with a small wire brush to nice copper shine . Please I need help what am I missing ?

FYI, I moved the above post into this thread due to the picture.

Okay when brake pedal is engaged I get a 12.8v reading @ socket. Install bulb nothing, Ive tried 4 diff bulbs

Thanks

CONFUSSED......... just asking here if I am getting 12.8v at socket when brake pedal is engaged why would I need to look at the turn signal switch? Thanks for your reply

Hy DKMcGee, If you are using a digital meter to do your testing they will give a reading when in reality there are only milliamps of current there, not enough to light the light bulb. We know the turn signals work, so there must be a diminished feed to the turn signal switch from the brake light switch. Bill Hanlon posted a link to the trucks wiring diagram, check that to find which wire provides power to the turn signal switch and make sure there is real power there, use a test light not a digital meter, hope that helps.

Took the double plug apart cleaned prongs checked voltage with my digital meter all good

These pics with and without brake engaged yet will not light the 1157

I can't tell from your pictures where the black meter lead is touching when you test the socket without the lamp installed.

The side of the socket where the bulb would ground out , and for some reason I couldnt DL the other pic showing 12.6v while brake pedal engaged. I dont see yet Im ordering a turn signal switch and hope that fixes issue.

Any possibility that the contact in the socket isn't aligned with the contact on the bulb when it's installed?

Hy DKMcGee, we have all given you our best advise on how to find the problem, but you don't seem to want to take our advice, so go ahead and throw new parts at the problem rather than make the tests we have suggested to verify that the brake light feed is making it to the turn signal switch. Good luck!

An interesting test would be to measure the voltage at the contact with the bulb installed, the socket grounded and the brake pedal pushed. I'm betting you'll find very little voltage.
If so, the problem is upstream resistance as 3B suggested earler.

Guys I GOT IT ! I pulled turn signal cleaned the 3 lil blades assembled and woo-la have brakes lights. Guys Thanks for all the info I never would of thought it would of been the turn signal learn something new every day . Thanks again

And I thank you for the advice