Brake lights won’t work?

[Nad_Yvalhosert]

Hey there so I have a 1994 k1500 and when I turn the headlights on the taillights come on in the back now I think it’s the brake lights that are constantly on along with the running lights because when I took the cover off the middle light and the bottom light are on constant. The top ones don’t come on at all

Does the 3rd brake light come on?

The power flow on the wiring schematic says brake power goes a few ways:

Fuse, brake switch, (for purposes of this discussion, ignore #'s 1&2)

1: out to transmission to lockup converter
2: out to cruise control
2: out to 3rd brake light
3: up the column to the multi-function switch, then out to the signals.

If you have a working 3rd brake light, the brake switch is good. So look at the multi-function switch.

 

[Nad_Yvalhosert]

By the way, the brake switch is not visible in your pictures. It is located on the brake pedal lever, at the pivot of said brake pedal lever.

 

[movietvet]

Yeah I just joined so I thought I posted it in wrong section tried to delete but can’t figure that out

If you can't figure it out, ask for help from a moderator

 

[davidmcclung576]

Ignore the side marker for second...
The amber light should have 2 main bulbs lit with parking lights on, and 2 bright bulbs lit with the turn signals flashing. Your pic shows 1 amber light, not sure if that's parking light or t-signal.
That 1 bulb will cause hyperflash. Fix that first.

Next, the side marker will flash with turn signals during the day, and alternate the signals with the lights on. It will NOT affect hyperflash.

It’s a turn signal flashing in the photo. So you’re saying there may be a bulb out in the corner lights? I’m not too concerned with all that I just thought maybe it would be good info to know to try to diagnose why the taillights are acting the way they are.

 

[davidmcclung576]

By the way, the brake switch is not visible in your pictures. It is located on the brake pedal lever, at the pivot of said brake pedal lever.

Thank you! That helps a lot. I appreciate all the input because I mean I can change oil and diagnose some issues but some things I just don’t know yet so….if anything this truck will be a learning experience for me

 

[davidmcclung576]

Does the 3rd brake light come on?

The power flow on the wiring schematic says brake power goes a few ways:

Fuse, brake switch, (for purposes of this discussion, ignore #'s 1&2)

1: out to transmission to lockup converter
2: out to cruise control
2: out to 3rd brake light
3: up the column to the multi-function switch, then out to the signals.

If you have a working 3rd brake light, the brake switch is good. So look at the multi-function switch.

No the cab light doesn’t come on.

 

[davidmcclung576]

No the cab light doesn’t come on.

Also I know the cruise control is funky well I’m told. That it accelerates while on cruise and doesn’t stop. So I was told not to use the cruise

 

[movietvet]

Are you sure you have the right bulbs, in the right positions of the taillights. Top 2 bulbs should be #3057 and the bottom one should be #3156.

 

[Hipster]

So you’re saying there may be a bulb out in the corner lights? I’m not too concerned with all that

How far do expect to get with this if you don't know if if you have have the correct bulbs in the correct spots or if they work to begin with???? Maybe you should start there before giving everyone the runaround.

 

[Jjbiskup]

personally i have the same truck (94k1500) and i had the same problem with my brake lights not coming on. first you should see if your third brake light comes on when pedal depressed, if it does its most likely a wiring issue. If it does not, what i did was get my hand under there and find the white plastic brake light switch and push it against the stud on the brake pedal lever. You should hear a click which is the relay activating, if you dont you should try to replace the switch or test the connector for voltage. If it does turn on what i did was fold up a little piece of 600 grit sandpaper and shim it slightly on the end of the switch which fixed my problem almost a year ago. Hope this helped!