no brake lights?

[flipflop_syls]

Hello Folks!

I have been working on a 66 c10 for a few weeks now trying to get it on the road. this is my first project with 4 wheels (chopper guy). Ive got the turn signals working finally, as well as head lights. I can not for the life of me get brake lights! Ive gone through the electrical system all the wires look fine, i replaced the brake switch as well as the headlight switch thing. any ideas?

[kieth]

Ground the light housing to the frame........Kieth

[flipflop_syls]

i figured since i had rear turn signals and its 1 bulb that it was grounded.... ill give it a shot though.

[Vernski]

A bad ground will cause all kinds of malady's even though some lights may work a bad ground does weird things that don't make sense. Ground em' to the frame the boxes on these old trucks are full of rust...Vernski

[ACK]

If the grounds are good, check the bulb contact alignment in the tail light buckets. I was suppose to have my truck inspected last weekend, but had to bail because the brake lights didn't work, the rear right blinker didn't work, and the rear left blinker flashed when signaling to make a right turn. This was all due to the rear right bulb contacts being slightly twisted out of position in the tail light bucket, probably rattled lose by all the pot holes. I pulled out the bucket, cleaned everything off good, realigned things, and all's working fine again.

[ray_mcavoy]

They're dual filament bulbs so they can still light up without a good ground. Basically what happens is they backfeed through the other filament and find a ground through that other circuit. They're usually dimmer than normal when that happens.

Another thing to check is the turn signal switch. The contacts are set up so they can override the brake light on one side or the other as necessary for the turn signal. If those contacts are bad, it can allow the turn signals to work okay but not allow power from the brake light switch to pass through.

[1963c-10]

Yeah, grounds are horrible on these trucks. You can't over ground them.

[tincan1966]

1) Is there 12V at the brake light switch orange wire?
2) With the brake pedal pushed is the 12V on the white wire?
3) With the pedal pushed, is there 12V on the white wire on both sides of the turn signal plug on the steering column?

If the answer was YES to all three, then with the pedal pushed is there 12V at both the yellow and green wires on the turn signal switch connector? (make sure the turn signal lever is not in the left or right turn position)

If the answer is no, then you have a failed turn signal switch-either the contacts are worn or it is burnt internally. Since you stated you have turn signals on the rear, I am going to bet on the white wire not making contact in the switch, unless you answered NO to either 1,2, or 3. if that's the case repair as necessary and resume testing in that order.

This is about a 10 minute test that will tell you exactly where you are losing the voltage.
There is no sense in running all around the truck checking bulbs. The bulbs are only 2 element and there's only 3 wires that run everything to the rear(unless you have backup lights.)
Stop and turn signals share wires, which originates from the T/S switch. If the turn signals work then that was your test for the harness from the T/S switch to the lights.

Always test from the source to the bulbs, it'll save a ton of wasted time. If you do not have power it doesn't matter what the bulbs are like.

[KDO]

Originally Posted by tincan1966

1) Is there 12V at the brake light switch orange wire?
2) With the brake pedal pushed is the 12V on the white wire?
3) With the pedal pushed, is there 12V on the white wire on both sides of the turn signal plug on the steering column?

If the answer was YES to all three, then with the pedal pushed is there 12V at both the yellow and green wires on the turn signal switch connector? (make sure the turn signal lever is not in the left or right turn position)

If the answer is no, then you have a failed turn signal switch-either the contacts are worn or it is burnt internally. Since you stated you have turn signals on the rear, I am going to bet on the white wire not making contact in the switch, unless you answered NO to either 1,2, or 3. if that's the case repair as necessary and resume testing in that order.

This is about a 10 minute test that will tell you exactly where you are losing the voltage.
There is no sense in running all around the truck checking bulbs. The bulbs are only 2 element and there's only 3 wires that run everything to the rear(unless you have backup lights.)
Stop and turn signals share wires, which originates from the T/S switch. If the turn signals work then that was your test for the harness from the T/S switch to the lights.

Always test from the source to the bulbs, it'll save a ton of wasted time. If you do not have power it doesn't matter what the bulbs are like.

In chasing the same issue on my 86, brake lights not working but flashers, turn and running lights do work. Guess I'll be changing a turn signal switch tomorrow! Thanks.

[elf w/capital T]

Tincan, thanks for the troubleshooting help! Yup, brought this thread back from the dead!