Primus IQ Trailer Brake Controller Issue...

[Blang]

My brother-in-law helped me install a trailer brake controller on my 2001 Silverado 1500. This is his specialty and he has done it successfully countless times. Everything appears to be connected well because everything works for the most part.

When I squeeze the manual brake application the brakes work but it says 'nc'... so I can't adjust the gain at all. It's like I have full brakes all the time. It works when I press the brake pedal as well. But it's frustrating because it gets jerky when I have to stop at a stop sign for example.

I really want to be able to adjust the gain.
I swapped it for an older primus controller and it more or less did the same thing except I couldn't manually apply the trailer brakes. I even tried connecting to a different trailer to make sure it wasn't an issue with the trailer. Any tips are appreciated. Thanks!

 

[mk378]

There are only 4 wires involved but they have to be connected properly. Always live, brake lights (goes live when brake pedal pressed), ground, and out to the trailer. These can be tested with a voltmeter. In particular bad grounding can cause all kinds of malfunctions.

 

[Blang]

There are only 4 wires involved but they have to be connected properly. Always live, brake lights (goes live when brake pedal pressed), ground, and out to the trailer. These can be tested with a voltmeter. In particular bad grounding can cause all kinds of malfunctions.

It seems so simple, right? Brakes work. They work when the brake pedal is pressed as well as the manual override. We added a ground yesterday to be safe and still the same. Thanks for the input. I'm not sure what else we can do to improve the grounding at all... ?

 

[meep]

What does the manual say about “nc”?

 

[spasm3]

What does the manual say about “nc”?

Nc means not connected, so there is a wiring fault. There could also be a lack brake magnet ground on the trailer causing this.

 

[Blang]

My brother-in-law spent some time on the phone with customer support today and they told him on those trucks there could be an extra blue wire that is for a third brake light for a shell or something. And so he must have tied into the wrong blue wire somewhere along the way. I think the mix-up happened because he put a new harness/connection at the hitch receiver and must have hooked up the wrong wire. Hope that makes sense. So it's working now. Just need to things dialed in. Queue the Ric Flair 'Wooooo!' Anyway, thanks for chiming in.