After Market Brake Controller Install

leathermaneod · August 12, 2022

Hi all,

I’m new so I apologize if this is in the wrong place. I googled hi and low looking for an answer to this and found nothing, so I’m posting to try to help others.

Today I tried to move my Tekonsha Primus IQ brake controller from my 2012 pilot to my new to me 2018 Silverado 1500. I had the GM wiring harness that came with my truck, so I spliced it to the Tekonsha harness from my Pilot, after cutting off the Pilot end. Im a commercial hvac service tech and used to working on vehicles as well, so this was all fairly mundane at this point. Well next I plugged in the brake controller to the junction box under that dash and got no lights. So I checked for power on the pins, nothing. Next I checked fuses, all good and had power. Next I google no power to brake controller plug every possible way I could think of and all I could find was a link to GM upfitters documents. This wasn’t totally unhelpful, but it was a little over my head at first. Well I dug into it and ended up removing the trailer brake control module above the spare tire and checking for power, I had 12v. There was lots of dirt in the harness so I sprayed the plug with electrical contact cleaner and applied some dielectric grease and plugged it back in. Now I had 12v under the dash too.
Next I plugged in the brake controller again and still nothing.

This is where things go downhill. I googled the pin designations for for my specific wiring harness model number from the pilot. The diagram I found indicated that I should have spliced red to blue and blue to red. I trusted the diagram and made the change. Plugged the brake controller in and nothing happened. About 3 seconds later I saw smoke from my brake controller wiring harness. I unplugged my brake controller as fast as I could. I still don’t understand what all went wrong, but that quick it ruined the little battery ground wire of the GM brake controller harness all the way back to the plug in the junction box under the dash. I was/terrified I damaged something in the truck, so I disconnected the negative battery cable and then disconnected all the plugs and removed the junction box to inspect it. I couldn’t find anything that looked damaged in the truck. Of course you really can’t see the board in the junction box though and checking the wires is really just a visual check. Hopefully nothing crazy turns up and hopefully my new brake controller and GM specific wiring harness work ok once I get them.

Keep your fingers crossed for me!