2nd Gen Non-Engine/Transmission Help! Brake lights and reverse lights stuck on!

[AUrban]

Very weird issue... I came out after work and my brake lights and reverse lights were stuck on. Of course, this and 20 degree weather made the truck impossible to start. But, even after getting it started, the brake lights and reverse lights are stuck. If I shut off the truck, the lights stay on. Relay problem? Is there anything I can do to shut them off short of pulling out the bulbs? My truck is outside idling now... any quick tips would be greatly appreciated.



Oh, there seems to be a "buzz" from under the dash when I push on the brakes... I could only hear it at idle though.

 

[AUrban]

Pulled fuses... lights still on. Pulled harness from brake switch, lights still on. ???

 

[AUrban]

Brake controller, unplugged. Unplugged the connector to the brake switch... lights are still on. I had my bed replaced over the summer. I wonder if some of the wires got pinched together? I'm out of ideas...

 

[CSnyder]

You have a short somewhere in the rear harness. Unhook your batteries until you can find it.

 

[Missouri Mule]

I agree with CSnyder wiring! You can try pulling the connector to back-up light switch see if it will kill the reverse lights.

 

[AUrban]

I think my conclusion is that it has to be something with the wiring to the rear of the truck. The really funny thing is that my reverse lights haven't worked since I bought the truck, and now they won't shut off! There used to be a trailer plug in the bed in addition to the connector at the rear bumper. When the bed was switched, I suspect some clever rewiring may have been done. I'm going to try and check it out tonight... better stock up on kerosene for the heater.

Thanks... I'll followup when I figure it out. Any other thoughts... feel free to throw out suggestions.

Tony

 

[dseabaugh]

The wiring harness to the rear connects at the front of the firewall on the left side around the brake booster I think. Unplug that harness to see if it is a short in that harness. I had to replace that entire harness after being rearended and smashing the trailer plug. The short fried that harness. They are also supposed to be prone to corrosion damage.

 

[AUrban]

Excellent. Thanks for the pointer. I will check there.

 

[PC12Driver]

The trailer wiring harness has an unswitched 12v power lead. Maybe this is shorting across the other wires and causing a backfeed? If you pull the trailer wiring relay (in the power distribution box under the hood by the driver's side battery) that'll cut the power to that lead. It's a bit of a stretch, since that would mean that four wires have crushed together, but ya never know.

 

[JDKammin]

I have seen where those trailermate tees will get corrosion in the connection and cause the problem you are describing.

 

[AUrban]

So, I went out tonight and pulled the trailer fuse from the PDB. The brake/reverse lights went out and my brake lights worked normally. Hooray! However, after putting the fuse back in and pressing the brake, both the brake & reverse lights stayed on, even after taking my foot off the brake. So I guess I have it narrowed to the trailer circuit... just have to see where the problem might be...



Thanks for everyone's help.



Tony