No brake lights. Brake light circuit diagram needed.

[ben2go]

I started at the tail lights and worked my way forward using a multimeter, I could not find power. I pulled the fuse and tested it for continuity and it was good. Probed the brake switch anally at the pedal and never found power. There are at least 7 wires running to it. I can only ass-u-me the hazards and signals run through the switch as well and that's why it has so many wires going to it. It started raining like a b++++ so I called it an evening. I need a wiring diagram for the brake light circuit. I can not locate one for my truck with the correct color coding. The hazards and signals work. Info in sig line.

 

[Supercharged111]

According to the Haynes, you should have an orange wire with constant power at the switch. It's not very detailed, but seems to make a straight shot from the stop/haz fuse with a splice along the way. That splice may be your Huckleberry.

 

[someotherguy]

I'm not the one to discourage troubleshooting, but if your hazards and signals work and the brake lights don't, the #1 suspect is the brake light switch. They are cheaply made (even originals) and don't last forever. They are cheap to replace. Replace it, and on 1988-1993 there is an adjustment procedure before it will work correctly.

Here's a thread about adjusting the 1988-1993 GMT400 brake light switch: https://www.chevytalk.org/fusionbb/showtopic.php?tid/180723/

Once you've got the new one installed, adjusted, and working - pop your old one open and discover the set of broken leaf switches/contacts in there.

Richard

 

[ben2go]

I'm not the one to discourage troubleshooting, but if your hazards and signals work and the brake lights don't, the #1 suspect is the brake light switch. They are cheaply made (even originals) and don't last forever. They are cheap to replace. Replace it, and on 1988-1993 there is an adjustment procedure before it will work correctly.

Here's a thread about adjusting the 1988-1993 GMT400 brake light switch: https://www.chevytalk.org/fusionbb/showtopic.php?tid/180723/

Once you've got the new one installed, adjusted, and working - pop your old one open and discover the set of broken leaf switches/contacts in there.

Richard

We checked today, and have no rear lights except running lights. No power at the brake light fuse. Is there another place to look before the fuse in the dash fuse block? I don't know if the relays are before or after the fuse and switches. I really need a circuit wiring diagram with wiring colors for my specific truck. I've seen several diagrams, but none of the colors match up to my truck. Most of the diagrams are for 93+ C1500.

 

[Mikes98]

We checked today, and have no rear lights except running lights. No power at the brake light fuse. Is there another place to look before the fuse in the dash fuse block? I don't know if the relays are before or after the fuse and switches. I really need a circuit wiring diagram with wiring colors for my specific truck. I've seen several diagrams, but none of the colors match up to my truck. Most of the diagrams are for 93+ C1500.

There's a fuse box in the engine bay; it's the power distribution center and typically has some high amp circuits with big fuses (25a). It also has a bunch of relays as well. There might be something in there that's causing your grief ...

 

[someotherguy]

There's a fuse box in the engine bay; it's the power distribution center and typically has some high amp circuits with big fuses (25a). It also has a bunch of relays as well. There might be something in there that's causing your grief ...

1995-up only. OP has a 1989..

Richard

 

[AK49BWL]

1995-up only. OP has a 1989..

Richard

However, the distribution block on the passenger firewall DOES contain many fusible links. It's possible one of them has burned up.

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If I had to guess I'd say that black fusible link may have blown, but if that was the case you wouldn't have headlights either. If the stop/haz fuse has no power on either side of the fuse, the hazard flashers wouldn't work either.... So there's a bit of conflicting info here lol.

 

[ben2go]

However, the distribution block on the passenger firewall DOES contain many fusible links. It's possible one of them has burned up.

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If I had to guess I'd say that black fusible link may have blown, but if that was the case you wouldn't have headlights either. If the stop/haz fuse has no power on either side of the fuse, the hazard flashers wouldn't work either.... So there's a bit of conflicting info here lol.

Yeah it's weird problem. No brake lights, no signals, and no hazards. It only has park lights front and rear along with bright and dim headlights. I tried tracing everything out but no jello. My son has been using the truck. I may have to jury rig a temp work around until I find the problem. I only get about an hour or two to work on it. We've been having bad weather so no work at all on it today and only a few minutes yesterday.

 

[someotherguy]

Conflicting info for sure. First post says "The hazards and signals work" then fourth post says "We checked today, and have no rear lights except running lights"

Beats me.. maybe provide better info for people to troubleshoot long distance. It's tough.

Richard

 

[ben2go]

Conflicting info for sure. First post says "The hazards and signals work" then fourth post says "We checked today, and have no rear lights except running lights"

Beats me.. maybe provide better info for people to troubleshoot long distance. It's tough.

Richard

That's correct. When we noticed no brake lights, we parked the truck. I checked the lights to see if signals lights and flashers worked, they did. Then my son had to drive it. When I got a chance to start looking into it deeper, none of the signals worked, no hazards, and no brake lights. All the lights we have are running/park lights and head lights. There's no power at the brake light fuse. Whatever caused the brake lights to fail I think caused the rest of the failures. The rain keeps coming and I can't work on the truck. I would like to figure this out in case someone else comes up with this problem.