Need help with factory Brake Controller

[2nd2none]

I have a 2015 GMC Sierra, I don't tow a lot so not much use on my itbc. I got an error of service trailer brake system and even check wiring a time or two. I used to regularly get the warning about the brakes on the dic. It's obvious the trailer brakes aren't working. I'm not knowledgeable in this area. But I did check to see if I'm getting voltage to the terminal for the brakes on the 7 pin connector. I used a test light. All pins work except for the trailer brake terminal, had my girlfriend step on brakes and even tried the brake slider switch above the headlight switches. Nothing. Last two times I hooked up my trailer I did not get any warning and not even a trailer connected message. I did have to replace the left turn signal fuse for the trailer during this mess, and the trailer brake j-fuse is good. I took it to the dealer and they were useless.

I know there's several components to check. Please help guys/gals!

[2nd2none]

I should also mention. The dealer said they couldn't find any error messages in the computer.

Is the brake controller completely dead maybe?

Please help!

[Davidj101]

You won't get any voltage on the brake connector with just a test light. The controller is looking for a load (the magnets) on the circuit before it senses a trailer being connected. So you either have to simulate the load or actually hook a trailer up to it in order for the controller to sense it and apply power to the circuit.

 

Since the controller isn't even recognizing a trailer being connected now, I'd suggest hooking up to a different trailer and seeing if it works on it.

 

If you don't have access to another trailer then I'd suggest having a friend hook their truck the your trailer and see if their controller senses the trailer brakes.

 

If you have one close to you, it would probably be worth taking the truck to a utility trailer place and see if they'll test the controller and maybe even the trailer for you.

[newdude]

There are codes that will set. C1114 is the most common. We've replaced many of the dash switches already for service trailer brake issues.

[2nd2none]

Thank you guys. Good info. I was wondering if it was my trailer, but thought it wasn't due to the fact I thought that pin in the connector always got voltage. I will see if I could use somebody else's truck or trailer to determine if it's my trailer or my truck before I put any time into diagnosing my truck. Using somebody else's truck or trailer is a whole other issue..ugh... lol. Thank you guys.

[2nd2none]

Also strikes me kind of funny that there were no codes in the computer when the dealer checked it, when it was set off numerous times... guess I will have to go down the checklist...

[ember1205]

Bad trailer wiring might cause errors, too.

[2nd2none]

Thanks for the replies guys. I'll check what you guys suggest and get back to you guys if it doesn't help.

[gmckenzie]

I had a "check trailer wiring" note on my DIC and lost my trailer brakes.

 

There is a TSB on it and it' got to do with dirt in a plug by the spare tire. Fixed now but a bit hairy at the time.

[BIGBRD7]

Could be brake fluid level, check service bulliten PIT5490. Dealer filled mine to the brim after I was randomly getting error message and no brakes, hadn't had a problem since.