Brake lights

[Tim W]

I have an issue thats got me stumped... my 94 silverado's brake lights work Intermentally But my third brake light works as it should.

I've checked the fuses and all fuses are good and I can hear the relay clicking, In fact I actually have power to the relay that I checked with a test light.

While checking the power with the test light in various locations, I seem to have power up until I get near the rear plugThen I lose power.

I have 2 yellow wires.One had a label on it that said brake light switch.. that one wasnt hooked up, it was taped back. When the brake is pressed I get power to that 1.But I do not always get power to the second wire.

I figured a new brake light Switch would fix the issue but it did not. My only other guess is possibly the relay is working Intermentally.
Any suggestions?

 

[Tim W]

While having box pressed on the brake pedal i did a little more wire probing. When I unplug the taillights and plug them back in I lose power.

I probed all the way to the drivers door and the brake light switch had power but the other yellow wire did not.

While testing , the brakes light just randomly came on worked correctly. I then showed power to the other wire.

Is the brake light switch wire, (yellow) supposed to be tied into the other yellow wire at the plug?

Im wondering if my new acdelco switch is bad or if maybe the relay is bad?

What do yall think

 

[GoToGuy]

Coffee break. Brake lights. When you say relay has power , that's a two fold answer. 1 does the relay receive activation power and 2 does the relay then close to send power out to do whatever it's function is ?
The high center brake light is separate circuit activated before rear brake lights. Have you looked at the OE service manual , section 8 electric circuit diagrams. Randomly connecting wires not knowing what circuit it is can lead to disaster.
Clean good grounds. Clean , connectors have continuity. Have checked bulbs, all good.

 

[Tim W]

I need a coffee break. The relay clicks when I press the pedal but Im not sure its sending power back all the time. The issue is intermittent. Its tuff doing this by yourself. Alot of getting up and getting down.

I havent connected any wires to anything. I haven't checked an OE service manual. I was looking on line to see if the loose yellow wire is supposed to tied in somewhere but haven't had luck.

I agree connecting random wires is a bad idea

I cant imagine the loose wire supposed to be just left there, but Im not an engineer .

Bubs are good, grounds are connected to a good clean source paint and rust free.

Blinkers, flashers, and taillamps all work as they should as well.

Im sure im missing something simple.

 

[Tim W]

Problem has been solved.

 

[Knoxvillin865]

Could you let us know what solved the problem?

 

[Tim W]

I remembered I did a multifunction switch a few months back and I depined the plugs to make them easier to fish through column.

I saw on a wiring diagram that the white wire also gives juice to the brake light switch.

I checked and the white wire was not fullly seated in the plug and was loose. I seated the wire all the way until it locked and my brake lights came on. Was it a Coincidence? Maybe, but they work now.
It was difficult for me to understand why they were not working. The wiring on my truck is 95% untouched.

The brake light wiring, taillamp, blikers, Lp lights, ect is 100% untouched. My truck doesn't even have trailer hook up wires spliced in So I figued it was something simple.