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Trailer Brakes Not Working

SouthpawHD

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SouthpawHD Enthusiast

SouthpawHD

Posted
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Picked up my TT with my new truck for its first tow and the trailer brakes aren't working. The DIC says "SERVICE TRAILER BRAKE SYSTEM". The manual just implies it's something with the truck.

 

Before calling the dealer tomorrow, any ideas what might be causing it?

bcnqrgd Enthusiast

bcnqrgd

Posted
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I wound up replacing the trailer electrical cord. Do all of the lights operate as they should, turn signals and all?

SouthpawHD Enthusiast

SouthpawHD

Posted
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All the lights work as they should.

 

I will check fuse tonight when I get home. It's raining now, so it'll have to wait.

 

I think I am going to call my local RV dealer and see if I can just plug in another trailer and start there.

SouthpawHD Enthusiast

SouthpawHD

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Took my truck to my local RV dealer, and per their test machine, everything is operating per normal on the truck, including the brakes. We were able to adjust the brake and see the gain changing on the DIC.

 

However, he did note that the connection was loose, so perhaps that is something to look at. I remember reading some time ago that some GM owners had similar problems with the connection not being real tight.

jhplak325 Enthusiast

jhplak325

Posted
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SouthpawHD, my travel trailer had a Bargman molded 7 plug and it was not a tight connection on my 2015, but was on my 2009.

 

I have replaced it with the Pollak 12-706 7 plug that GM recommends in a TSB (I can't find the TSB number at the moment, as soon as I find it , I will post it). This plug is a much tighter connection.

 

I will know this Friday if all is good when I head out for first trip of the year.

 

Hope this helps.

SouthpawHD Enthusiast

SouthpawHD

Posted
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SouthpawHD, my travel trailer had a Bargman molded 7 plug and it was not a tight connection on my 2015, but was on my 2009.

I have replaced it with the Pollak 12-706 7 plug that GM recommends in a TSB (I can't find the TSB number at the moment, as soon as I find it , I will post it). This plug is a much tighter connection.

I will know this Friday if all is good when I head out for first trip of the year.

Hope this helps.

That's great info, thanks!!!

 

I will order one right away as that's still cheaper than taking my trailer in for a check.

 

Edit: on second thought, since it involves wiring, I'll have to take it in for service.

rjkinpa Enthusiast

rjkinpa

Posted
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had same problem, make sure plug is all the way in with the cover latching bottom of plug. Otherwise plug is loose causing service trailer

spasch Enthusiast

spasch

Posted
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We get this with built in brake controls and high end aftermarket systems. 99% of the time there is a cooked magnet or shorted wire inside one of the trailer hubs. If it's intermittent and wiggling the plug does not make it freak out, (errors on the display) normally a magnet wire is worn down or chafing inside one of the hubs. Does your trailer perhaps have marine axles (grease fitting in the end of the slindle)? If so pumping in grease can blow the seal and hose the brakes down with grease. If this happens the wires get out of position and worn down.

 

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tom18287 Enthusiast

tom18287

Posted
Posted

have the same issue. how i deal with it is make sure you plug in the trailer with the truck OFF, then it works every time

 

 

is there a fix from the dealer?

SouthpawHD Enthusiast

SouthpawHD

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Well I believe I have everything working now. My camper dealer told me the plug was loose and to crimp the inside pieces of the plug from the trailer, so that is what I did and so far so good.

 

Thanks for all the advice. I will likely order the Pollak plug described above just to have one on hand.

SouthpawHD Enthusiast

SouthpawHD

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On the trailer plug, there are 7 female prongs (2 in each female slot) that connect to the 7 prongs that connect into the truck. I used a small screwdriver and just pushed each individual prong closer to each other, thereby making the connection tighter.

 

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sugarjohnson Enthusiast

sugarjohnson

Posted
Posted

Just posted this on another forum hope it helps someone else.

 

Updating an older post with hopes of helping someone else avoid the massive hassle I had with this issue. I have a 2015 3500 and got a brand new 5th wheel over winter. Very first drive I got the "check trailer wiring" but put the RV in storage and cleaned up all the wiring over winter, grounds positive bus bar etc. figuring most likely fixed it. Well pulled the RV out this week to get ready for season. Guess what? Same damn message. All functions worked on the trailer except when the message popped up and then went away. I went through everything and I mean everything looking for causes. Checked plug resistance on trailer, checked truck, redid ground, inspected brake wiring, redid all pinbox crimps. I went so far as to disconnect my in bed plug thinking maybe that had a short. Nothing helped and the truck would continually cycle the messages "CTW" "trailer connected constantly.

I finally gave up and took the trailer up to my RV dealer who is great. The tech I crawled under the trailer and went immediately for the trailer brake wiring. He found a pinched wire where the bundle was attached to the axle. I had these down and looked at them earlier today and saw nothing. He said he does it by feel and noticed the pinch. He cut it out redid the connection and guess what? It fraeaking worked! Took him exactly 7 minutes.

Tech said the new trucks are so sensitive to the resistance that any defect in the trailer brake wire that causes the truck to not see good resistance will throw the error.

I hope this helps someone else troubleshoot.

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