NEED HELP No trailer brakes with factory integrated brake controller.

gmcman

Guru
Original poster
Dec 12, 2011
4,577
Not sure if this falls under "Technical" or "Towing".

My 2012 Yukon Xl with the factory "JL1" brake controller, is not seeing the trailer as well as not providing power to the brakes. I assume I won't have brakes if the DIC doesn't acknowledge the trailer.

Red wire is connected, fuses are good, Tech 2 shows that when I move the slider, the percentage for the manual input increases and decreases accordingly.

The 7-pin connector is clean on both ends.

No stored codes

Trailer brakes work on a different vehicle.

With a DMM attached to the Yukon's 7-pin connector on the trailer brake and ground terminal, I get constant fluctuations from 3.7V to 4V. When I move the slider or press the brakes, same voltage fluctuations.


Any ideas?
 

Mooseman

Master Blaster
Moderator
Dec 4, 2011
22,841
Ottawa, ON
Connect a good load on the truck's brake pin, like a 55w light, and see if it sees that and try the controller to see if it powers the light. Maybe the wire is broken on the back of the connector. I had a broken ground wire on the back of the connector on the TB.
 
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gmcman

Guru
Original poster
Dec 12, 2011
4,577
Forgot to mention, all the lights work on the trailer, even the brake lights with the Yukon connected.

I pulled the 7-pin from the receiver hitch and it looks new inside.
 

mrrsm

Lifetime VIP Donor
Oct 22, 2015
6,153
Tampa Bay Area
You've probably already viewed this from another resource.... But JIK not as yet... The Factory Owner's Manual for the 2012 GMC Yukon has THIS information in Chapter 9-79 about that Trailer Hitch Seven Pin Electrical Connector:

2012YUKONTRAILERBRAKES.jpg
Excerpt from this Downloadable Source PDF:

 
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gmcman

Guru
Original poster
Dec 12, 2011
4,577
Yes, thanks....I did see the wires not connected and I have since connected them.

Definitely a head scratcher now.
 
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mrrsm

Lifetime VIP Donor
Oct 22, 2015
6,153
Tampa Bay Area
Try Pulling BOTH Fuses mentioned in that Image above and sort of "Gently Exercise" the Blade Contacts. Then confirm continuity (KOEO) on All Four Fuse Pin Points with a Lighted Probe. One Last Thought... If those Two Wire Contacts are identical... for B+ Power... Try Reversing them at the Fuse Panel and then re-test with the Light Probe afterwards.
 

TollKeeper

Guru
Dec 3, 2011
6,975
Brighton, CO
In your first post you said you connected the red wire.. Apparently there are 2 that need to be connected. 1 is for the 12v feed to the trailer, the other is the 12v feed to the integrated brake controller.
 
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gmcman

Guru
Original poster
Dec 12, 2011
4,577
I have tried both red wires, seperate, and together.

Only thing I can think of now is the module above the spare tire...either that or a wire in or out of the module.
 
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Reprise

Lifetime VIP Donor
Jul 22, 2015
2,575
Would you happen to be 'dkad260' on tahoeyukonforum?

If not, check this out, as that poster is apparently going through the exact same thing. He's up to troubleshooting w/ a Tech2...


(I figured two ppl having the same (?) problem at the same moment in time was more than a coincidence, so... )
 
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gmcman

Guru
Original poster
Dec 12, 2011
4,577
Well,.so much for the witness protection program.....lol.....JK.

Yeah, thanks, that's me. There was another thread a ways back but they went with an aftermarket controller.
 

gmcman

Guru
Original poster
Dec 12, 2011
4,577
Curious if anyone has the pinout for the TBCM or the brake controller switch on the kick panel.
 

gmcman

Guru
Original poster
Dec 12, 2011
4,577
No progress yet, working with GM TDS to get the Tech 2 to work as a pass through.

What a show.
 

mrrsm

Lifetime VIP Donor
Oct 22, 2015
6,153
Tampa Bay Area
Just In Case.... If THIS Trailer Brake System Relay is FUBAR... and is present and Mounted under your Spare Tire as per this VOP (Video Original Poster) ...Have a look-see at THIS Video:


And a Broad base Diagnostic that settles in around the Trailer Brake Control Module on a Full Size Truck that may have some Pretty Good Diagnostic Information for you, as well:

 

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