No brake lights or turn signals on 1994 Chevrolet Silverado.

[aquariuscsm]

When headlights are on, tail lights glow, but when applying the brakes the brake lights don’t light up and the turn signals also don’t work. I’ve checked the turn signal fuse and the brake light fuse and both are good.

Any ideas? Thanks in advance!

 

[eljefino]

Check the turn signal and hazard switches. See if you can trigger the bulbs with either. Brake light current flows through both when they're in "rest" position.

How's the third brake light, check its bulb. It should be straight-wired to the brake pedal switch, bypassing the turn signal switch.

If there's trailer wiring, check it for issues.

 

[aquariuscsm]

Small update. She’d left her hazard switch on for some reason, I turned it off. I followed her home and her turn signals are now working, but still no brake lights.

Tail lights work, turning signals work, but brake lights do not work when you depress the brakes.

 

[Trav]

Check the brake light switch. Simple, just unplug it and jump the wires.

 

[aquariuscsm]

Could it possibly be the brake light switch that’s on the brake pedal? I found the switch. Is there a way to test the switch without removing it and if not how do I remove the switch?

 

[Trav]

That's the one, sure just unplug it and connect the wires with a jumper.

Edit: I just looked at it, it has 6 wires so I will see if I can find the 2 you need to jump. I was thinking at that age it still used a 2 wire.

 

[aquariuscsm]

That's the one, sure just unplug it and connect the wires with a jumper.

Edit: I just looked at it, it has 6 wires so I will see if I can find the 2 you need to jump. I was thinking at that age it still used a 2 wire.

Awesome! Thank you!

How exactly do I remove the switch? I can slide it up but it looks like it’s somehow attached and I can’t quite figure it out.

 

[Trav]

This is about the best explanation I can find. I looked at the wiring diagram and that was not very helpful, it is connected to the hazard and other lights. Unless you want to go at it with a power probe I would say check all the fuses and relay if applicable, if it all looks good change the switch, they seem to be a very common problem.

https://www.youtube.com/results?search_query=94+siverado+brake+switch+removal

 

[mk378]

Since it is the same bulb filaments for both functions, the brake light circuit also passes through the turn/hazard switch on the column. When not active on a blinker function, the brakes are patched through to the bulbs.

But definitely rule out the pedal switch and the fuse first.

 

[aquariuscsm]

This is about the best explanation I can find. I looked at the wiring diagram and that was not very helpful, it is connected to the hazard and other lights. Unless you want to go at it with a power probe I would say check all the fuses and relay if applicable, if it all looks good change the switch, they seem to be a very common problem.

https://www.youtube.com/results?search_query=94+siverado+brake+switch+removal

Good video Trav, thank you! That was the exact thing I was looking for, what is holding the brake light switch on and how to remove it

 

[wtd]

I would say a bad ground for the rear lighting harness. Do you have access to a wiring diagram so that you can see where that ground is located? I had a similar issue with my 98 Chevy 1 ton truck and it was a bad rear lighting harness ground. On my truck the factory ground was supposed to be in the rear of the left hand side frame rail but someone had moved it to the metal panel under the tailgate and some of the eyelets were bad. Your truck's ground may also be in the left frame rail.

 

[aquariuscsm]

I installed a new brake light switch and still no brake lights. I’ll poke around to see if I can tell if any ground wires have come undone like another poster mentioned. If not this may be beyond my expertise. I hate dealing with electrical issues.

 

[wtd]

I installed a new brake light switch and still no brake lights. I’ll poke around to see if I can tell if any ground wires have come undone like another poster mentioned. If not this may be beyond my expertise. I hate dealing with electrical issues.

The ground doesn't have to have come undone to not work correctly. It's probably corroded or possibly just loose. If you find it, I would take it off and clean the eyelets, the stud or bolt that they go on, and the metal that the eyelets rest on at the bottom of the bolt or stud.

 

[clinebarger]

I usually test for 12vdc at the White Wire at the Turn Signal Switch with the pedal depressed after checking the Brake Fuse.

The White Wire comes directly from the Brake Switch.
The Dark Green Wire & the Yellow Wire goes to the bulbs.

If you have 12vdc at the White Wire but nothing on the Dark Green or Yellow wires.....The Indicator Switch is bad.

Tail Lamps/Parking Lamps share the same ground as the Turn/Stop part of the bulbs.

The "circuit boards" that the bulbs twist into are notorious for going bad! Yes.....I've seen both be bad!

 

[aquariuscsm]

Well, mystery solved and truck fixed!!

I went back over all of the fuses and there it was, this fuse hidden in the corner all tucked away that said "Stop" under it. I pulled it, it was blown! Put in a new 20 amp fuse and, bam!! Brake lights work again!!

Thank you to everyone that helped me

 

[Lubener]

Well, mystery solved and truck fixed!!

I went back over all of the fuses and there it was, this fuse hidden in the corner all tucked away that said "Stop" under it. I pulled it, it was blown! Put in a new 20 amp fuse and, bam!! Brake lights work again!!

Thank you to everyone that helped me

Fuses blow for a reason. They don't wear out. Don't be surprised if it blows again.

 

[TheLawnRanger]

This is what BITOG is for.

 

[ekrampitzjr]

On these '90s Chevy trucks, the turn signals and 4–way emergency flashers are on separate relays. The brake lights share the circuit and the fuse with the 4–ways, not with the turn signals. So the turn signals can work if thebrake lights are out.

The 4–way flasher relay is the problem. It overheats and burns up, especially when towing a trailer with the added lamps. It doesn't seem to matter whether you use a "heavy duty" relay. If the overheating is bad enough, the plastic on the relay will shatter, which allows the metal innards to short against metal under the dashboard, draining the battery. It will also blow the fuse, which kills the brake lights too.

If you turn on the 4–ways using the switch on the steering column and they don't work, that means the relay overheated. Now you need to check your brake lights. The turn signals will still work because they are on a separate relay and circuit, so don't be fooled into thinking you have brake lights because the signals still work.

The 4–way flasher relay is tucked under the dash in front of the driver. Once it fails the first time, the replacements will not operate the 4–way flashers for long, even for just the truck without a trailer. The wiring to the relay was damaged from the overheating.

These trucks have more than their share of electrical problems.