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Discussion Starter · #1 ·
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!
 

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Do you have a small battery for the trailer breakaway? It is probably dead or close to dead and receives holds a little charge after being towed awhile and then discharges as it sits until the next tow. I don't know if this is the cause, but if all your wiring checks out this may be the culprit?
 

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Definitely a trailer problem. The truck checks the trailer brakes when you first plug it in. Also if you have a crappy ground on the trailer it does the same thing. I pull multiple work trailers and when the brakes or wiring on trailer are arking it does that.
 
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A lot of the time that I come across this it's the wires that run inside the axles.
 

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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
 

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Here is information from ALLDATADIY:

# PIT4366G: Check Trailer Wiring Message Displayed On DIC - (Aug 7, 2014)
Subject: Check Trailer Wiring Message Displayed On DIC Models: 2009 - 2013 Chevrolet Avalanche 2009 - 2014 Chevrolet Suburban, Tahoe 2007 - 2013 Chevrolet Silverado 2014 Chevrolet Silverado 2500/3500 2007 - 2013 GMC Sierra 2014 GMC Sierra 2500/3500 2009 - 2014 GMC Yukon Models With Integrated Trailer Brake Controller (RPO JL1) The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern
Some customers may experience an intermittent "Check Trailer Wiring" message in vehicles equipped with ITBC (Integrated Trailer Brake Controller) RPO JL1 and no DTC's stored.
Below are two possible causes for this concern:
1. This message may be displayed each time the trailer's running lamps, turn signal lamps, or brake lamps are turned on, especially if the trailer is equipped with a large number of lamps. This condition is most likely caused by insufficient trailer grounding and the trailer ground wiring will need to be repaired and/or upgraded. 2. This concern could be caused by a poor connection at the 7-way trailer connector. There are several manufacturers of 7-way (trailer side) connectors and many do not comply with the SAE standard specifications. Some 7-way (trailer side) connector plugs may not properly engage the truck's 7-way connector socket and cause open circuits. Also, they may cause deformation and excessive wear of the terminals on the truck's 7-way connector socket. Over time this will lead to poor terminal tension between the 7-way (trailer side) connector plug and the truck's 7-way connector socket. Since the Trailer Brake Control Module is always monitoring the vehicle and trailer circuits/components, a poor connection at the 7-way connector can cause a "Check Trailer Wiring" message on the DIC. Recommendation/Instructions
1. Inspect and clean the ground wire (normally 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. If the condition still exists, perform the following procedure: 1.1 Remove the original trailer ground wire (normally white wire) from the trailer side of the 7-pin trailer connector.
1.2 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 an 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. 1.3 Obtain a sufficient length of minimum 10 gauge (5.0 mm) white wire and fasten with ring terminal (PN 12103512 or equivalent) to the trailer chassis at the same location as the original ground wire.
1.4 Install and fasten the other end of the new ground wire into the trailer side of the 7-pin trailer connector
1.5 Install conduit on the original and new trailer ground wires and secure the conduit to the existing trailer harness.
2. Engineering has recommended the use of Pollak Heavy Duty 7-Way (Trailer Side) Connector Plugs. Pollak is the OEM manufacturer of the truck's 7-way connector socket; by using a Pollak Heavy Duty 7-Way (Trailer Side) Connector Plug will ensure proper fit when the two connectors are mated. Pollak's website is: Electrical Connectors, Electrical Switches & Electrical Sensors: Pollak. Once at the home page select "Connectors" and then "Heavy Duty 7-Way Plugs and Accessories". Note : If the truck's 7-way connector socket terminals are deformed or have excessive wear, it will be necessary to replace the truck side connector (with a GM CCA Customer Care and After sales Part) along with the trailer's 7-way connector plug to a Pollak HD.
 

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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.
 

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Same here I use a small irrigation head adjustment screw driver to spread them so they contact better
 

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My 43' Toyhauler has started this lately also. Everything works so I will try these simple fixes.

Thanks,
 
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I had the same "Check Trailer Wiring" message on my 2015 Sierra 3500 followed by 4 loud dings. Just about drove us crazy! Everything on our Titanium 5th Wheel worked. Went to 2 GM Dealers who could not find the problem. I finally figured out that if I pulled the radio fuse inside the passenger side of the dash, that there was no more Ding, Ding, Ding, Ding! I also changed out the 7 wire plug on our trailer with a Pollack but that did not change the warning. Also a friend scraped the ground to bare metal but that did not help either. After driving for 2 hours and seeing the Warning constantly on the dash, it finally quit. I have no idea what caused the problem and no idea what fixed the problem, but I replaced the radio fuse and it has been normal ever since.
 

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2. This concern could be caused by a poor connection at the 7-way trailer connector. There are several manufacturers of 7-way (trailer side) connectors and many do not comply with the SAE standard specifications. Some 7-way (trailer side) connector plugs may not properly engage the truck's 7-way connector socket and cause open circuits. Also, they may cause deformation and excessive wear of the terminals on the truck's 7-way connector socket. Over time this will lead to poor terminal tension between the 7-way (trailer side) connector plug and the truck's 7-way connector socket.
I am betting the above is the most likely cause of the problem.

A cargo trailer I haul used to to this all the time, but other trailers never caused it, so I knew it wasn't a truck problem.

A trailer dealer told me about the issue I put in bold above. He said some brands of trailer plugs are slightly smaller than the SAE spec, and wobble in the OEM truck receptacle.

I bought a new trailer pigtail, installed it and the problem has never come back. The new plug fits much tighter in the truck receptacle.
 

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Thanks Roger, I changed the trailer plug twice, so that was 3 wiring plugs and not one made any difference. Finally I just wanted to get rid of the Ding, Ding, Ding, Ding! I am sure glad that radio fuse comes out easy. By the way if you have to remove that fuse cover, put a screw driver or some metal object at the bottom on the inside and pull on it. Those covers are on tight. The radio fuse is on the Passenger side.
There is a You Tube on how to remove the fuse cover:
 

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Discussion Starter · #13 ·
The check wiring message went away after replacing the trailer connector cord with a slightly longer one. The old one just didn't have enough slack and would occasionally pull out just enough to case the message to go off. Since the new connector cord, we haven't experienced the warning message again.
 

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I sprayed down the connector with dielectric grease and mine all but went away. Very rare it comes on now.


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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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Definitely a trailer problem. The truck checks the trailer brakes when you first plug it in. Also if you have a crappy ground on the trailer it does the same thing. I pull multiple work trailers and when the brakes or wiring on trailer are arking it does that.
^^^^^^^^ What SouthFloridaGMC said. Had this on my last trailer. Ended up being the ground connection where the brake wiring that runs through the axle meets the other brake wiring on the frame rail. PITA to find but found it on accident.
 

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Well I got too optimistic. First camping trip this weekend and 1 hour into traveling guess what? "Check trailer wiring" is back! Nothing left for me to do on this while on the road because the hubs need to be checked and all trailer brake wiring checked. This on a brand new 5th wheel. Real happy guy this weekend 400 miles with a near constant warning chime in my ear.

Trailer is under warranty and back at dealer as we speak. He's pulling hubs today to do full inspection and if need be said he will rewire the whole brake system.

Sent from my SM-G920V using Tapatalk
 

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It appears my problem was because my breakaway switch was wired incorrectly. It completely had melted and I replaced it and rewired it. Drove 4 hours yesterday and no ding at all.


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Well I got too optimistic. First camping trip this weekend and 1 hour into traveling guess what? "Check trailer wiring" is back! Nothing left for me to do on this while on the road because the hubs need to be checked and all trailer brake wiring checked. This on a brand new 5th wheel. Real happy guy this weekend 400 miles with a near constant warning chime in my ear.

Trailer is under warranty and back at dealer as we speak. He's pulling hubs today to do full inspection and if need be said he will rewire the whole brake system.

Sent from my SM-G920V using Tapatalk
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
 

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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
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.
 
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