"Check trailer wiring" warning on my truck display

[jurecska]

Hello,

I towed first time over the Memorial Day weekend with my new truck and fifth wheel:
2024 GMC Sierra 2500HD
2023 Jayco Eagle 321RSTS

Every once in a while I received warning on my truck with message of "Check trailer wiring". Then it said that brakes are connected. I stopped multiple times to check: unplug/re-plug and check lights. everything was working.

Does anyone have an idea how to investigate this issue?

Thank you very much for your help, regards, Attila

[Murff]

Loose ground wire?

Murff

[ARoamer]

Our 2020 does the same. Try to keep your trailer wire plug connections clean and use a light coat of dielectric grease on the contacts. I do a manual brake test with the slider when the warning displays and the brakes have always worked. Ocasionally I get a right turn signal inop warning also but it's always working.

[Grumpy]

I use to get that on our 2015 Silverado until I added the 7 pin connector in the bed. That eliminated the wire hanging down and bouncing. I think there was just enough flex that one of the connectors lost contact on occasion.

[Rustic Eagle]

Welcome to JOF

Here's a couple recent JOF threads on the subject that may be helpful:

https://www.jaycoowners.com/forums/f...age-95968.html

https://www.jaycoowners.com/forums/f...t-77238-2.html

Bob

[ARoamer]

Being intermittent, the message is quite annoying but shouldn't be ignored. There could be a serious issue. Always do a visual and a manual brake test.
Truck side GM Service bulletin for 7 way connector-
https://static.nhtsa.gov/odi/tsbs/20...14860-0001.pdf

[Scott]

We had that problem with our truck and it ended up that the brake wire on the trailer was nearly worn through. Only 4 wires from the strand were still intact. You might want to carefully inspect the wiring on your trailer.

[Marine71-76]

We had the same issue twice on our 2008 F450. The first time, (under warranty) one of the brake lines on the unit was wrapped around the spindle. The second time, DW was driving and went over the I-80 bridge just right. Turns out the connectors on the driver's side brakes were corroded and one had broken. Keep telling her she needs to slow down!

[jetlag]

Don't have the warning in the truck, but sometimes the right turn signals will not work initially. Found out reconnecting the connector from trailer to truck fixes it. I need to check the plug connections

[armentaaw]

Had this issue on my 2020 3500 hd and I would activate turn signal and it would go away.

[CAG]

Originally Posted by jurecska

Hello,

I towed first time over the Memorial Day weekend with my new truck and fifth wheel:
2024 GMC Sierra 2500HD
2023 Jayco Eagle 321RSTS

Every once in a while I received warning on my truck with message of "Check trailer wiring". Then it said that brakes are connected. I stopped multiple times to check: unplug/re-plug and check lights. everything was working.

Does anyone have an idea how to investigate this issue?

Thank you very much for your help, regards, Attila

I spray both male and female connections with silicone spray. It lubes the connection and does not draw dirt like grease.

[kirkelli]

when i first got my 5th wheel i was constantly getting a Throttle position error code and only when towing the trailer. The error would throw the truck in limp mode and turning ignition off and back on would usually clear it up but not all the time.. I had the Truck at the dealer 3 times, first two at Ram of the West in Roseville they could not duplicate the problem.. The last time at Hunter Ram in Lancaster they knew right off the bat what the problem was.. They replaced the in bed trailer connector explaining the connector on some Ram models would not engage the locking tab on trailer harness causing enough of an intermittent disengagement on the trailer harness that caused a cann buss error to the Throttle position sensor. Never had any problems after the connector was replaced.

[jetlag]

Originally Posted by CAG

I spray both male and female connections with silicone spray. It lubes the connection and does not draw dirt like grease.

Originally Posted by armentaaw

Had this issue on my 2020 3500 hd and I would activate turn signal and it would go away.

[QUOTE=kirkelli;1114278]when i first got my 5th wheel i was constantly getting a Throttle position error code and only when towing the trailer. The error would throw the truck in limp mode and turning ignition off and back on would usually clear it up but not all the time.. I had the Truck at the dealer 3 times, first two at Ram of the West in Roseville they could not duplicate the problem.. The last time at Hunter Ram in Lancaster they knew right off the bat what the problem was.. They replaced the in bed trailer connector explaining the connector on some Ram models would not engage the locking tab on trailer harness causing enough of an intermittent disengagement on the trailer harness that caused a cann buss error to the Throttle position sensor. Never had any problems after the connector was replaced.[/QUO


Lol, we are at Hilton head and I will go to the auto parts store and get a can of electronic cleaner and spray the crap out of the connectors.

[Underway]

Attila, Had a similar if not same problem with my 2019 3500HD Silverado, intermittent and aggravating Trailer Brake warning on display - finally found a YouTube video that matched the issues I was having and it was a very easy fix. Link here: https://youtu.be/Wn3sgO-tLjU. OEM part of Amazon only $40 (GM Genuine Parts 84108373 Black Trailer Brake Control Switch Assembly).

Good Luck,
Underway

[Kim Gass]

Happens to us a lot. Evertything is fine at home and then we travel 3miles of bouncy road and voila there is the warning display. I won't point fingers but in every case it was just a loose connection at the seven pin connector.. Having spray is a good idea.

[Dbunke]

Originally Posted by Underway

Attila, Had a similar if not same problem with my 2019 3500HD Silverado, intermittent and aggravating Trailer Brake warning on display - finally found a YouTube video that matched the issues I was having and it was a very easy fix. Link here: https://youtu.be/Wn3sgO-tLjU. OEM part of Amazon only $40 (GM Genuine Parts 84108373 Black Trailer Brake Control Switch Assembly).

Good Luck,
Underway

On my 2015 Silverado I had seen another you tube video that said before replacing that $ 40 switch. Manual slide the controller and let it snap back
several times. It worked for me, haven't had the error come back for at least a year now. If the slider doesn't get used much it must loose contact. Give it a try.

[Jeff4310]

I have exact same problem, I cleaned connections, It helped but still see a little. I am going to check ground between trailer and truck. I have anderson ultimate hitch. @021 GMC Sierra 2017 Jayco 24.5 ckts. Have you any luck on diagnosis? thx Jeff

[Tom G]

Originally Posted by jurecska

Hello,

I towed first time over the Memorial Day weekend with my new truck and fifth wheel:
2024 GMC Sierra 2500HD
2023 Jayco Eagle 321RSTS

Every once in a while I received warning on my truck with message of "Check trailer wiring". Then it said that brakes are connected. I stopped multiple times to check: unplug/re-plug and check lights. everything was working.

Does anyone have an idea how to investigate this issue?

Thank you very much for your help, regards, Attila

Hopefully you got it fixed. I'm having the same issue now; constant "Check Trailer Wiring" messages where lights work but not the brakes.
Trusted RV Mechanic found a loose ground wire on the RV side of the wiring harness. So I had brakes until I drove home and parked the trailer, went to hook it up 3 days later and instantly got the CTW message again.
Trusted RV Mechanic will be looking at the trailer two days from now. Based on web research, it may be that the solar panel is overfeeding the battery and making the GM app think it's not working right. The plan is to remove solar from the electric wiring and check again.
The Mechanic's hours are going to be at my expense unless he finds some blatant violation of electrical code or common sense on Coachmen's end.
More later.

[Grumpy]

Originally Posted by Tom G

The Mechanic's hours are going to be at my expense unless he finds some blatant violation of electrical code or common sense on Coachmen's end.
More later.

Just shows an RV is an RV is an RV.... also

[Kevin Cooper]

Different truck, Ram. Different fifth wheel manufacturer on YouTube had same problem. Would get warning once in a while. The problem was the electric brakes. He figured it out when the brakes totally quit working. So, get your brakes checked. The magnet fell apart.