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Tell us about your truck, the EXACT message you receive on the DIC, the conditions under which you get the message, and what you've done to troubleshoot.
Hi Ron, I pretty much covered everything in posts 10 and 12. The message was "check trailer wiring", followed by "trailer connected!" My fifth wheel is a 2005 Titanium. The trailer brakes work, the lights all work, and yet I get this warning. That was Nov 2015 and March 2016. Last year Nov 2016 I drove to California and back to Canada without any problems. This Nov 2017, I drove the first day, no problem, then the 2nd day the same warning. I pulled the fuse! I will head back to Canada end of March 2018 and I am almost certain I will get the same warning and have to pull the fuse. I have had the truck to 2 GMC Dealers, St. George, Ut, and El Centro, Ca and neither can find the problem. They basically said it is in my trailer. My Titanium trailer had new axles and brakes installed in 2012 and I never had any problem with my 2009 GMC 2500. I just don't know where to look to find the problem. I am just glad I can stop the Ding, Ding, Ding, Ding by pulling the fuse to the radio. My wife and I don't mind not having a radio, so it is not really an issue. It upsets me that my truck thinks there is a problem that is not apparent otherwise. Thanks, Al.
 

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What I have experienced is the pins in on the trailer plugs get to spread out. Unplug push in the pins with screwdriver and plug back in. Solves my problem.
I had the same problem on my previous camper. Spreading the contacts forked for a while but got to be a PITA.

My solution was to change out the power cord on the camper. It solved the problem. I then used some dielectric grease on the connections and voila, NO more problems
 

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Sugar Johnson, did you ever find out the real problem? I still have the Ding, Ding, Ding, Ding problem, then I pull the fuse, and drive. Very frustrating! Everything seems to work well on my trailer so I don't know where to go next
Yes I did get an answer and have been trouble free since my last post. I was getting the "Check Trailer wiring message." Mine turned out to be bad wires inside one of the brake drums. When they built my 5th wheel they left one of the wires to long and it rubbed inside the drum. The wire would then short against the inside of the drum. My hub was replaced under warranty and no further issues since with about 17,000 miles of further towing. Hope this helps.
 

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Yes I did get an answer and have been trouble free since my last post. I was getting the "Check Trailer wiring message." Mine turned out to be bad wires inside one of the brake drums. When they built my 5th wheel they left one of the wires to long and it rubbed inside the drum. The wire would then short against the inside of the drum. My hub was replaced under warranty and no further issues since with about 17,000 miles of further towing. Hope this helps.
Well thank you SugarJohnson and 407driver, I think you have narrowed my search down to the brake drums or the power cord on my trailer. I appreciate your quick replies.
 

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Well thank you SugarJohnson and 407driver, I think you have narrowed my search down to the brake drums or the power cord on my trailer. I appreciate your quick replies.
I would never have thought to look in a brake drum for wiring problems. Thanks, you have increased my knowledge base.
 
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I would never have thought to look in a brake drum for wiring problems. Thanks, you have increased my knowledge base.
At the time I didn't either as the trailer was brand new. I spent days trying to locate the problem. Shouldn't have surprised me based on how they build these trailers!
 

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Trailer builder would've never seen that, as they buy assembled brake axles, bolt 'em on and wire to the pigtails on the back side of the backing plate.
 

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Trailer builder would've never seen that, as they buy assembled brake axles, bolt 'em on and wire to the pigtails on the back side of the backing plate.
I agree your correct on the axles coming assembled. What is surprising is the transporter who drove this to the lot didn't see it since it happened almost immediately after picking it up. Then again i wonder how much a transporter would care?
 

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The hauler could've had the ol' reliable P2/P3 controller, instead of the complicated/finicky IBC option (to fix a problem that doesn't exist) from the mfr.

Also, many times those axles on/off the trailer have sat, outside, for who knows how long before the hauler hooks up.
And when they actually are put into use, the back side of the drums are all rusted up, lacking in magnet contact. So the hauler would've felt it was normal in lacking effective brakes on the trailer.
 

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Hi Ron, I pretty much covered everything in posts 10 and 12. The message was "check trailer wiring", followed by "trailer connected!" My fifth wheel is a 2005 Titanium. The trailer brakes work, the lights all work, and yet I get this warning. That was Nov 2015 and March 2016. Last year Nov 2016 I drove to California and back to Canada without any problems. This Nov 2017, I drove the first day, no problem, then the 2nd day the same warning. I pulled the fuse! I will head back to Canada end of March 2018 and I am almost certain I will get the same warning and have to pull the fuse. I have had the truck to 2 GMC Dealers, St. George, Ut, and El Centro, Ca and neither can find the problem. They basically said it is in my trailer. My Titanium trailer had new axles and brakes installed in 2012 and I never had any problem with my 2009 GMC 2500. I just don't know where to look to find the problem. I am just glad I can stop the Ding, Ding, Ding, Ding by pulling the fuse to the radio. My wife and I don't mind not having a radio, so it is not really an issue. It upsets me that my truck thinks there is a problem that is not apparent otherwise. Thanks, Al.
Al - When the message is CHECK TRAILER WIRING, the truck's computer is telling you that there is likely a problem with the trailer, not the truck. Now, I have seen reports that there were problems found near the back bumper of the truck with this message, but the truck is usually spot-on in determining where the problem is. You can have wiring that is shorted somewhere, even inside the axle housing, or the brake drums, or the ground has detached or is poorly made. Check both sides of the wiring on the 7-way.

If you get the CHECK TRAILER WIRING followed immediately by TRAILER CONNECTED , that sounds to me like a problem with the 7-way plug on the trailer where the truck detects a problem then immediately the problem goes away when TRAILER CONNECTED displays. I have seen several reports of the 7 way plug not quite making correct contact with the truck's recepticla and the solution was to buy a new 7-way for the trailer that was an exact match to the truck. Some are EXACT match, some are CLOSE match - you want EXACT. Also I used a bronze rifle cleaning brush .22 cal from my gun cleaning kit to clean the contacts and to make sure a good connection was being made between truck and trailer. Just an idea.

Here is some general info that may be of some help:

Symptoms - Trailer Brake Controls

Important: The following steps must be completed before using the symptom tables.



  1. Perform the Brake System Vehicle Road Test (See: Hydraulic System\Testing and Inspection\Component Tests and General Diagnostics)before using the Trailer Brake Controls symptom tables in order to duplicate the customer's concern.
  2. Review the system operation in order to familiarize yourself with the system functions. Refer to the following:

Visual/Physical Inspection



  • Inspect for aftermarket devices which could affect the operation of the Trailer Brake Control system. Refer to Checking Aftermarket Accessories .
  • For vehicles displaying a TRAILER NOT CONNECTED message with a trailer connected.
  • Inspect the trailer brake connector and circuits for proper connections, perform the following steps:

  1. Verify SSR circuit 47 pin A to the trailer connector pin C for continuity.
  2. Verity SSR circuit 1750 pin B to ground and to the trailer connector pin B for continuity.

    • If all circuits test normal the vehicle TBCM system is not at fault, otherwise most associated circuit faults on the vehicle side will set DTC's in the TBCM.
    • Insure the trailer is equipped with electric over electric brakes - only trailers equipped with electric brakes will be recognized and function correctly with TBCM.
    • If the trailer is equipped with hydraulic brakes this trailer will not be recognized by the TBCM. The vehicle chassis to trailer connector ground or the trailer ground circuits or trailer brake electric magnets are likely at fault.
    • The Trailer brake connector should measure less than 2 ohms of resistance between pins A & B of the trailer side connector. Note - a minimum of one fully functioning axle of brakes is required for the TBCM system to function correctly.
Symptoms Testing

Some customers may experience an intermittent Check Trailer Wiring message in vehicles equipped with ITBC (Integrated Trailer Brake Controller) with no DTC stored. This message may be displayed each time the trailer's running lamps, turn signal lamps or brake lamps turn on - especially if the trailer is equipped with a large number of lamp loads.

Check Trailer Wiring Message on the DIC


  1. This condition is caused by insufficient grounding between the trailer and vehicle.

    • To correct this condition, perform the following procedure:
    • Inspect and clean the ground wire (white wire) connection on the trailer side of the 7-pin connector.
    • Make sure that the wires inside the trailer side connector are clean and securely fastened.
    • If an electrical junction box exists on the trailer, make sure the wires inside the junction box are clean and securely fastened.
    • Once this procedure is complete, check to see if the condition has been corrected:
    • Remove the original trailer ground wire (white wire) from the trailer side of the 7-pin trailer connector.
    • Install a ring terminal (PN 12103512 or equivalent) to this wire and fasten the ring terminal to the metal or aluminum chassis of the trailer using a M6x1x20 self taping phosphate zinc coated screw (PN 11515925 or equivalent).
    • Pre-drill trailer chassis location with a 3/16" hole. Make sure the trailer chassis location is clean of paint or coating material prior to installation. Galvanic corrosion between dissimilar trailer and screw metals may require that this ground location be periodically cleaned.
    • Obtain a sufficient length of minimum 10 gauge (5.0 mm2) white wire and fasten with ring (PN 12103512 or equivalent) terminal to the trailer chassis at the same location as the original ground wire.
    • Install and fasten the other end of the new ground wire into the trailer side of the 7-pin trailer connector.
    • Install conduit on the original and new trailer ground wires, and secure the conduit to the existing trailer harness.

  1. Verify the condition has been corrected.
Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .
 

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Hi again Ron, we just got back home from California. When we left, it was warm out and the Check Trailer Wiring message and Ding, Ding, Ding, Ding started again. I drove 10 miles, pulled over and pulled out the radio fuse. Drove through Las Vegas and did not see another alarm on my dash. I replaced the fuse to the radio and never had another alarm for the next 3 days on the way home to Manitoba. For some reason my alarm seems to happen when temps are warm but not when it is cool or cold out. Any ideas what would cause that? Thanks, Al.
 

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Hi again Ron, we just got back home from California. When we left, it was warm out and the Check Trailer Wiring message and Ding, Ding, Ding, Ding started again. I drove 10 miles, pulled over and pulled out the radio fuse. Drove through Las Vegas and did not see another alarm on my dash. I replaced the fuse to the radio and never had another alarm for the next 3 days on the way home to Manitoba. For some reason my alarm seems to happen when temps are warm but not when it is cool or cold out. Any ideas what would cause that? Thanks, Al.
Temperature will make resistances change. Warm leads to higher resistance. The controller is checking the resistance of the brake coils. Sounds like you're borderline somewhere. Coil(s) bad-ish, connections, grounds, etc.

Sent from my XT1254 using Tapatalk
 
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I know of nothing specific, except to get the DVOM out and start checking the wiring on the trailer, and possibly the wiring at the back of the truck's frame leading to the 7 way plug. Trailers are notorious for bad grounds. I read a post some time ago that said the problem was found to be at the back of the truck. Only one report of this. I've only owned two trailers and both of them had problems. I rewired both of them; problems resolved.

It almost sounds to me like you get the error message immediately followed by the TRAILER CONNECTED message is that right? If you remove your 7-way and then re-insert it, what happens under that circumstance? I assume you are plugging into a receptacle in your bed? If so, and your cord has enough length, try connecting to the receptacle on the bumper to see if it behaves the same way.

Hope you enjoyed your trip. I'm in Phoenix now, weather this winter has been great, but it is going into the upper 90's next week.
 

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1080362


Wanted to add this photo and note to your post to help with others troubleshooting this issue. I had intermittent chimes in the 2016 Duramax for trailer connected/disconnected. Some trips, it was rarely chiming and on another, it drove me insane for 500 miles. After a lengthly replacement of every inch of brake wiring and components, I chased it down to bad brake wiring in my axles. Note, this was inside the Dexter axle, hidden from view, to pass the brake wiring from the L to R side. Vibration had caused three bare spots in the wiring of one of the axles.

After replacing the above wiring, it's never been so quiet. The net-net here is IF you're getting an intermittent chime for the trailer connected/not connected warning, and you're reasonably confident the plug is clean and NOT the issue, check ALL of your wiring from that point back to the brake assemblies under the trailer for shorts or damaged insulation. Check the wiring if run inside the axles! That was my cause of miles of frustration. Safe travels!

-Vance
 
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The last couple of times I towed my 30' Trailer with my new GMC Sierra Denali truck, I got a message that said "check wire connection". The trailer is hooked up just fine, brakes, lights, etc. are fine.

Any idea what is causing this message to flash? It goes away after awhile, but it still causes worry and stress.

We took the truck to our dealer, who tested everything, worked on it a couple of hours and could find nothing.

Has anybody else seen this message while towing? Appreciate any advice you can give.

Thanks!
In the manual it says do not set trailer brake sitting still. Ours did this half way home. I found where it says to drive 20-25 mph and set brakes while moving. Ours hasn’t done this since
 

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Just returned home from a 24 day trip with truck & trailer. First 1/3 of the trip was great, but half way between Kingman & Williams, AZ and the rest of the way home kept getting the message - Check trailer wiring & chimes and then Trailer connected. Sometimes it would be on rough roads and some times road would be smooth as glass. All lights and brakes work fine. Any ideas where to start looking. Thanks

Steve
I just had this experience with my 2018 3500HD. I had a great service place run down the problem (to the tune of $1K) to be broken magnets associated with the brakes of my horse trailer. WTH? I cannot believe the warning takes control of the DIC as well as CONSTANT dinging. I hope the engineer that designed that gets the problem, the incessant dinging, and can never figure it out.
 

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I just had this experience with my 2018 3500HD. I had a great service place run down the problem (to the tune of $1K) to be broken magnets associated with the brakes of my horse trailer. WTH? I cannot believe the warning takes control of the DIC as well as CONSTANT dinging. I hope the engineer that designed that gets the problem, the incessant dinging, and can never figure it out.
Yeah, right. The engineer who designed that system has probably read every book on trailers but has never seen one, let alone pulled one. Probably lives in the city and rents a Zipcar...if he has a license, that is.

I say that as a full-blown nerd with undergraduate and graduate degrees in engineering, so don't hate on me, engineers.
 

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Oh, have you guys every experienced a wheel speed sensor fault on these trucks while pulling a trailer?....


Truck computer cuts the power to the trailer brakes.
 

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Oh, have you guys every experienced a wheel speed sensor fault on these trucks while pulling a trailer?....


Truck computer cuts the power to the trailer brakes.
Another excellent reason to ditch the ITBC for an aftermarket brake controller...
 
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