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Service Trailer Brakes

NWI Denali
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NWI Denali Enthusiast

NWI Denali

Posted
Posted

I've got this code up, I have replaced BOTH the dash switch AND the relay under the spare tire to no avail. I have cleaned out the port on the bumper too. Gonna have my buddy scan it and pull the code for me. I'm out of ideas?

MrWeller Enthusiast

MrWeller

Posted
Posted

Did you check the fuses under the hood as well? When I blow my trailer brakes fuse, that is the message I get.

newdude Senior Enthusiast

newdude

Posted
Posted (edited)
18 minutes ago, NWI Denali said:

2017 6.2

All fuses are good and brake fluid is halfway between MIN and MAX

 

 

Three common parts.  Switch in the dash, the trailer 7 way in the bumper and the trailer brake control module.

 

Not sure what "relay" you replaced under the truck, as these don't use the relay like 07-13.  I'm assuming you meant the module?

 

You will probably find a C1111, C1112 or C1114 if its just a trailer brake code.  There might be another one causing it however.  

Edited by newdude
  • Like 1
NWI Denali Enthusiast

NWI Denali

Posted
  • Author
Posted

Yes sorry, brain fart. I replaced the module. This is what I replaced. 

 

Do you know what those code #s correspond to? Do they each correspond to one item, the switch, the module, and the bumper port? 

 

Thanks for the quick responses. You seem very knowledgeable on the subject.

31Y9aOFDjPS._AC_SY1000_.jpg

NWI Denali Enthusiast

NWI Denali

Posted
  • Author
Posted

I hate just blindly throwing parts at it but I was pretty confident from everything I read online that it was either the dash switch or the module. Oh well, ya win some and ya lose some I suppose. Lol

newdude Senior Enthusiast

newdude

Posted
Posted
27 minutes ago, NWI Denali said:

Do you know what those code #s correspond to? Do they each correspond to one item, the switch, the module, and the bumper port? 

 

Thanks for the quick responses. You seem very knowledgeable on the subject.

 

 

 

Eh, somewhat.  C1114 typically is found with a bad control switch in the dash, but can also lead to the 7 way.  The module codes are more specific to the module.  It does ideally require some circuit testing based on the code(s) you find.

 

DTC C111B 03

Trailer Brake Power Control Module System Voltage — Voltage Below Threshold

 

DTC C111B 07

Trailer Brake Power Control Module System Voltage — Voltage Above Threshold

 

DTC C111B 5A

Trailer Brake Power Control Module System Voltage — Plausibility Failure

 

DTC C1112 00

Trailer Brake Signal to Trailer Brake Power Control Module Circuit — Malfunction

 

DTC C1113 01

Trailer Brake Power Control Module Enable Circuit — Short to Battery

 

DTC C1113 02

Trailer Brake Power Control Module Enable Circuit — Short to Ground

 

DTC C1114 00

Trailer Brake Control Solenoids Control Circuit — Malfunction

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NWI Denali Enthusiast

NWI Denali

Posted
  • Author
Posted

I just replaced the bumper plug now too. So all 3 parts are new. Still no luck. Code still there.  🙄 Really at my wit's end now. Could it be a dirty connection further upstream from the bumper?

 

Here was my bumper connection. Pretty clean I thought and dielectric grease in it.

 

 

 

 

20210825_130409.jpg

MrWeller Enthusiast

MrWeller

Posted
Posted

Is it giving you this message when hooked up to a trailer or anytime the truck is on? 

 

I had similar issues with our gooseneck cattle trailer and threw all three of those parts at the problem as well.

 

I did a couple more things to help resolve my issues.

 

When I got the service trailer brakes message, my trailer was blowing fuses under the hood. I had to dig into the trailer brake wiring and repair a couple wires and replace those fuses in the truck to make it go away.

 

Keep us posted...

  • 2 weeks later...
NWI Denali Enthusiast

NWI Denali

Posted
  • Author
Posted

So I finally pulled the code. Looks like a pretty generic code, loss of signal. U0137. Could this be a bad ground? Any insights? Anyone ever have this code?

 

 

20210907_205436.jpg

  • 1 month later...
smk1500 Enthusiast

smk1500

Posted
Posted

following, my 2015 lt 5.3 randomly throws the service trailer brakes up on the dash a couple times then goes away for a while(couple weeks) then does it again and stops again.

swathdiver Senior Enthusiast

swathdiver

Posted
Posted

You have to pull the internal trouble codes to begin to solve this without throwing money away.  Get a subscription to the shop manual at AllDataDIY so you can use the trouble shooting guide.

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