Stumped me maybe you too?

[79BIG10]

Today I was driving along and a cop pulls me over. I wasn't speeding or anything so I was wondeirng why? He pulled me over to tell me my brake lights weren't working. So I came home and starter diagnosing. Here's the way I went about it and the results:

1. No power at the light socket at the socket or at the quick plug.
2. No power at the firewall junction.
3. I replaced the fuse and still no brakes worked.
4. I checked the brake pedal switch (push button) and even jumped the connection with no help.
5. I followed the path of the wire to a relay by the fuse panel and replaced it. Still nothing.
6. I'm getting power to the fuse port at the fuse box and the push button switch.
7. The turn signals, hazards and side markers all work just not the brake lights themselves.

You stumped too? Even the shop manual doesn't have anything else on this to help.

[87 STEPPER]

Its gotta be your switch if you have emergency flashers this proves that the wiring is all good all the way out to the back of the truck and if theres pwr @ the fues & the sw. then it must be internal in the sw.

Check the sw. with an ohm meter if it cks good then it may be a broken wire @ the sw. follow it untill you find the bad portion.

Good luck and let us know what you find!

[syntech]

try your ground wire, i've found that many times that my brakes went out on my truck, and my dads 69 c-10 that the ground wire's are to blame,just take and clean the contact point for the ground with a wire brush. if that dont work go to autozone and get a new light socket, in the HELP section. if those dont work, nor the post from 87 stepper, then im stumped.

[Jonboy]

check the dimmer switch on the floor also.

[pugs]

1st of all was the brake switch adjusted properally

[79BIG10]

Jonboy- How would the dimmer switch affect the brakes?

pugs- It's adjusted and still nothing. I even jumped the wires themselves and didn't get any lights.

I've narrowed it down somewhere in the cab. It's not getting power at the firewall and it's getting power at the brake switch. I'm going to see where the wires lead me and see if there's something shorted out or loose.

[79BIG10]

UPDATE- I went out and still no brake lights. I am not getting power at the firewall so I'm thinking something inside the cab. But I did notice that the lights are bright when the lights are on for night driving.

This really is driving me nuts.

[pugs]

maybe pull the wire block off the fuse block on the firewall, when I worked at a gm dealer years ago we had problems w/ alot of vans. the same thing was happening no brales or at times other lites and other things wouldnt work, and what happened is that it would get corrided at the wire/ fuse block, spray it out real good w/ electrical cleaner, dry w/ air and possible take a small file and clean up the contacts

[rpatowers]

I'm having the same problem with my 72. No break lights. Someone above mentioned checking the ground wire. Where is the ground wire?

[trkklr77]

ground wires are at the tail lights.

i also just lost my tail lights and dash lights, i have brake, blinkers, heads, and backups, i was able to jump every thing but tails. i even tried another switch and nothing, i chased and checked the 4wire to the ass and finaly fixed a pinched wire from years ago, stripped and reconected and still nothing.

i had one popped fuse but i replaced it and it hasent popped again. still nothing

[Longhorn Man]

the ground is fine... the turn signals work.
The fuse box and associated wires are fine... again, the lights work.
Was there power at the brake light switch?



If so, replace the turn signal switch.

[79BIG10]

Originally Posted by Longhorn Man

the ground is fine... the turn signals work.
The fuse box and associated wires are fine... again, the lights work.
Was there power at the brake light switch?



If so, replace the turn signal switch.

That's what I'm thinking may be the problem. The brake lights use the same lights as the turn signals but the hazards aren't working now. I'll have to get a new one and get it replaced.

[bluex]

My brake lights quit working once and it was the turn signal switch in the column. The turn signals, hazards and tail lamps worked but the brake lights would not.

[79BIG10]

I played with the wiring and it's get power into it but not always out of it so it's the culprit. This next week I'll be replacing it on my vacation. Maybe I can get it fixed and the Blazer as well.