Service trailer brake system/check trailer brake wiring FIXED!

[zmnypit]

So for the last two months I have been all over this forum, Duramax forum as well as Google searching for an answer for the service trailer brake error on my 15 Sierra 2500 Denali. I have a 2017 24' all led tilt trailer that was purchased new and its never worked on my truck. I also get the service trailer brake system with no brakes or lights when I use it. When I  hook it up to my buddies 09 Duramax all lights, brakes etc work fine.

 

2nd trailer is a 2010 18" car trailer, non led, with brakes. When I pull it I get "check trailer wiring" then shortly after get the "service trailer brake system"

 

I've replaced both plugs with the Pollack plug with same result. Traced and re traced both truck and trailer wiring with no luck. Added grounds, wiggled the connector, cleaned all the contacts etc, nothing seemed to work. While sitting there this afternoon I took a flat headscrew driver and bent each pin outward a fuz until it was really tight when plugged in and just like all the lights and brakes work with no issues on both trailers. Two months of researching and It was so simple. I'm  posting this for the next person that comes along with the same issue. I never saw anyone mention adjusting the prongs of the truck connector so hopefully this helps someone. 

[crankman]

Glad to hear you fixed that, I shared your pain for quite a white on my 2015 tried pretty much everything including what you did. I solved mine with a cord strain relief that hold the weight of the trailer cord up. It was only on my Big Tex trailer that threw the check trailer wiring code they used a heavy guage thick black cord and it would eventually works it way just enough loose on the interstate to throw that code.  

[gcflower]

Thank you all for your ideas!  Most of the "fixes" described in the forum will work, at least for a while, but the problem will not have been addressed.

It certainly hasn't been addressed by GM in either of their TSBs PIT5311A & B (for the different years affected).  In fact, GM has the audacity

to blame the trailer-side wiring and/or the "...trailer-side connectors that do not meet the SAE specification".!!

 

Why hasn't anyone noticed (or mentioned) that the only trucks having this problem have the 7-way/4-way combo plug oriented with the 

7-way on top?  GM certainly won't mention it (see below), and you know the folks in the trenches in the Service Departments have probably

been told not to say anything to the customer.  You know the TSB did not arise out of thin air, but because of a large number of errors 

arising...with customers who have the combo plug with the 7-way on top.  Read on, if you're interested:

 

The real problem, and the reason folks have not had the error with older trucks, Fords, etc. is because GM came up with a great idea that

was poorly implemented.  They figured combining a 7-way and 4-way plug would save using converter plugs (correct) and save customers 

having to carry converters for boats and other 4-way wired trailers.  Probably a nice gesture overall.

 

However, they did not bother to spec that the 7-way has to be on the bottom of the 7/4 combination plug.  If you walk a dealer's lot, you'll see

some of the trucks have 7-way on top, others have it on bottom.  The truck-side 7/4 combo plug snaps in very nicely to the bumper with its cute little spring clips (another good idea), but the plug can NOT be inverted to put the 7-way on the bottom, where it should be, and like it has been for years.  The two bottom

terminals in a 7-way, when it is normally oriented with the truck-side lid lifting UP. are the GROUND and TRAILER BRAKE. 

 

Hence the problem with GM trucks that have the 7-way on top:  as the trailer side plug and wire hang and wiggle (imagine that, what a surprise for the GM engineers!), one or both of the two terminal connections (GROUND &/or BRAKE) can lose contact intermittently, causing the "DING, DING, DING:  CHECK TRAILER WIRING" followed shortly by "TRAILER CONNECTED" as the terminals reconnect.  This is also why your "Trailer Gain" display on trucks that have 

that in the info cluster will "grey out" and not show any activity when the connection is loose, then light back up to the normal orange and show activity

 when the connection is tight.

 

The bumper stamping is apparently done in batches, or perhaps at different locations, resulting in some bumpers having the 7-way hole on top

and others with the 7-way on the bottom.  Since the plug can not be inverted and GM did not think to spec the bumper stampings correctly, they

choose to place the source of the problem with the trailer-side wiring!!  Drill and add your own ground wire indeed!  Sloppy and lazy on GM's part.

Or buy a new trailer-side connector (at your expense), because yours probably "...does not meet the SAE specification".  Really??

 

The REAL fix would be for GM to swap out your current bumper stamping with one having the 7/4 combo plug oriented with the 7-way on the bottom.

I can't imagine GM would ever voluntarily do this, unless there were enough safety-related problems &/or accidents involving lack of trailer braking.

Why wouldn't GM at least provide the Pollak trailer-side connector to the customer and recommend they visit their favorite RV service center? 

Or perhaps reimburse the customer for the cost of the Pollak trailer-side connector?

 

All of the affected vehicles are $ 50,000 plus, so a gesture of customer goodwill on the part of GM to really fix this problem (instead of

placing blame on the trailer side) would certainly be reasonable.  Wait!  What was I thinking?!  If they can get customers to foot the bill by

not being transparent about their engineering snafu (for at least five model years!), nobody in GM has to be accountable.

 

I'm going to buy the Pollak trailer-side plug and start surfing the local and regional salvage yards for a "correctly" stamped bumper.

Good luck to you all,

Gordon

Sacramento,  CA

 

 

[[email protected]]

I have also been having this problem over and over for 3 years. On long trips we opt to drive the 2007 rather than the 2017 2500 HD due to the continuous beep-beep-beep occuring with the "check trailer wiring" followed by "trailer connected". 

 

I have pried the prongs out with brief results. dozens of times

 

Replaced both ends 3 times with Pollack plugs. took it to the dealer with no help, and they wont disable the warning beep which cannot be turned off by consumer. $174.00

 

Installed the Tekonsha Prodigy RF Wireless Trailer Brake Controller in an attempt to circumvent factory controller which proved even more troublesome as it drops signal multiple times wile on long trip. $339.00

 

And am now convinced the problem is in the gmc design with the socket door on truck opens downward(rather than the traditional upward) and the weight of the cord is not allowing the plug end to catch the mechanical socket door notch effectively. 

 

Next attempt will be with a new socket replacement by Reese which utilizes the traditional design that opens upward. If this doesnt work I will do the thing I originally attempted to avoid due to cost,  Replace factory system with complete aftermarket controller.

 

I guess $62,000 wasnt enough to spend on a truck to become eligible for a solution from GMC for a GMC  errorOuty o

 

 

Rlc

2017 GMC 2500 HD, Duramax work duty

[pumpmck]

I have been having this problem on a 2014 Chevy Silverado that I just got. My problem looks like it was the brake signal shorting to the frame at several of the jumper connectors near each wheel on the trailer. I also spread the trucks connector pin inside the trucks 7-pin

receptacle. If you look closely at the connector pin you will see that it is a U-shaped pin and you can use a small blade screwdriver to spread the pin so it makes better contact with the trailers plug pins. Also, the top 2 pins are the brake signal and ground. The top left one looking at the receptacle is the brake signal and top right one is the ground. Several notes talk about bending these pins toward the outside of the plug, but I don't really think that will do much. The receptacle pin  slips inside the trailers pin opening and over time the U-shaped pin isn't making a good contact as it has lost its tension.

     I found a pdf file that says that the truck is looking at the trailer brake line to determine whether a trailer is connected to the truck. I don't think the brake and tail lites are even checked. My truck has both 7 pin and 4pin receptacles and 7pin is on top.

[C45]

Bottom line is Chevy has taken entirely to many shortcuts on all their trucks from 2014 and on 1500 and 2500. I'll never buy another Chevy again.  Our company uses both models plus I've had a personal.  I'm on my sixth truck and ALL HAVE ELECTRICAL AND OTHER ISSUES. one truck would just die when braking and turning almost causing multiple head on collisions and they just don't know why! Chevy is a piece of ****** that's why

[Chief Redneck]

Did the "Service Trailer Brake System" come on when you did not have a trailer connected?  That is when I get the warning.  It does not do it all the time and it comes on out of no where and randomly.