Hit some electrical snags

[AndrewB]

As the red wire originates under the cover of the trailer relay, I removed the red wire from the #74 connector block. With that removed the brake lights are not light.

[patrickt]

Alright. You now have the red wire disconnected at both the brake light switch and the trailer relay, and the lights are out. Both ends of that red wire should not show 12v+. Put a VOM on it and see if that wire is hot with 12v+.

[AndrewB]

Originally Posted by patrickt

Alright. You now have the red wire disconnected at both the brake light switch and the trailer relay, and the lights are out. Both ends of that red wire should not show 12v+. Put a VOM on it and see if that wire is hot with 12v+.

There is no voltage on the red wire. However there is 12v on the pink wire in block #70 that the red wire would connect to if it was not pulled.

[patrickt]

That's the problem. The RED wire and PINK are the same wire. When operating normally, the 12v+ comes through the brake switch from the green wire and out through the PINK/RED wire to the trailer relay. With that wire disconnected from the switch there shouldn't be 12v+ on it, but there is. Somewhere that PINK wire is shorted to a hot wire. Now, if you run a separate jumper wire from the brake switch to the RED wire that goes in to the trailer relay, everything should work normally. You can then figure out why that pink wire is shorted to hot at your leisure.

[AndrewB]

Originally Posted by patrickt

That's the problem. The RED wire and PINK are the same wire. When operating normally, the 12v+ comes through the brake switch from the green wire and out through the PINK/RED wire to the trailer relay. With that wire disconnected from the switch there shouldn't be 12v+ on it, but there is. Somewhere that PINK wire is shorted to a hot wire. Now, if you run a separate jumper wire from the brake switch to the RED wire that goes in to the trailer relay, everything should work normally. You can then figure out why that pink wire is shorted to hot at your leisure.

Thanks Patrick - very much appreciated. I'll trace out the pink wire tomorrow and post my results.