Trailer Wiring - 1998 C1500
 

I'm wiring a Tekonsha Prodigy electric brake controller into my truck and I'm having difficulty locating the switched 12v source that's activated by the brake pedal/stoplamp switch. The switch is all but innaccessible and the wiring diagrams in the GM manual are not terribly clear about this. There's mention of a blue wire which is an auxilary circuit for electric trailer brakes but no mention of how to use it. Any hints would be very helpful. Thanks!

Re: Trailer Wiring - 1998 C1500
 

The tekonsha will take a 12v power source that is switched by the ignition. There is an another connection that will go to the brake circuit to signal when braking is occuring. These are two separate connections.

Some gm trucks do have a wire run to the back for this purpose. Look at the trailer wiring harness where it goes into the factory loom. You may find it there. Most people just use a scotch lock connector and tie into the brake light circuit just after the brake switch. You just need to determine which wire is controlled by the switch.

Re: Trailer Wiring - 1998 C1500
 

I ran into problems on my 95 model when I tied in to the brake wires because of the turn signal. I ended up taping into the wire for the 3rd brake light. My truck had the wiring at the hitch from the factory and each wire was labeled but the other end was not attached to anything. It seems that the blue wire (for the brakes) and orange (+) wire were bundled next to the firewall behind the brake booster.

Re: Trailer Wiring - 1998 C1500
 

He is looking for the brake switch wire, not a hot wire. The wire that activates the controller when you hit your brakes.

These can be difficult to access on this truck. The wire you are looking for is white. I'm sure you've been able to find it up by the brake switch harness. If you follow the wires coming out of the harness you should be able to find an easier way to access it down lower. Believe it or not, the wires actually run down low where you can reach them easily on this truck...you just have to trace them from the switch above if possible.

Call me at my shop if you need any more help finding it. I just so happen to do this for a living.

479-524-0111

Buck

Re: Trailer Wiring - 1998 C1500
 

Thanks all. I'll look for the white wire.

Re: Trailer Wiring - 1998 C1500
 

Got it done last night by studying my GM service manuals and especially the instrument panel to wiring harness junction connector. Turns out, it wasn't the white wire it was the light blue wire. Inserted a test probe and pushed the brake pedal - Bingo! 12v on the meter.

Thanks again for the comments.

Re: Trailer Wiring - 1998 C1500
 

before you wire it up...check under the hood next to the brake cylinder or in the left kick panel their should be a 3 or 4 wire harness for electronic brake controllers the other side of the connector should be in you glove box when the truck was new

Re: Trailer Wiring - 1998 C1500
 

that's what i thought also, until my chevy dealer told me they only do that on the 'new' body style chevy's.

found it funny that my 2000 1 ton dually did'nt have the wires available for electric brake switch. only cost $100 for someone to do it.

maybe i was supposed to buy it for the fuel economy and the cadilac like ride. who'd of thought i was going to use it to pull big trailers??

Re: Trailer Wiring - 1998 C1500
 

I looked all over the the brake controller wire harness that's somewhere on my truck. It's easier to pull new brake controller and ground wires from the back to the front.

Re: Trailer Wiring - 1998 C1500
 

If you guys need a wire diagram of your trucks you can goto a car audio store and have them print one up, or pm me I have a few on a disk here that I can print and fax as well.