I've had the "trailer disconnected" message as well as the "check right/left turn signal" messages. I have had the brakes not work but that seemed to be driven by either having the truck running when I plugged in (for some reason the 2022 GMC wants the engine off) or plugging and then replugging. Shutting the engine off and restarting it seems to correct the issue with not being recognized.
I saw a post elsewhere that there was a GM Tech bulletin that indicated the trailer plug was at fault. I had this issue on a 2013 and solved it using an EzConnector system on the truck and camper. Expensive but so much better than a Bargman plug/jack. I'll be swapping my 2022 to that as soon as the parts are available.
My 2009 GMC 2500HD 6.6 LMM regularly gives me the "Check Braking System" display where I have no trailer braking. I replaced the control module with genuine GM part and it still gives me the message. This is a serious issue and GM MUST resolve it!
This has happened to my 2016 2500HD Silverado a few times. The warning comes on for a few seconds, then goes off. I am going to clean the 7 way and see if that helps. If not, I think I will change out the 7 pin receptacle.
I found out that if I plug in the truck while the truck is turned on, I get error messages on the trucks display that the trailer is not connected. If you turn the truck off, disconnect and reconnect the trailer plug then turn the truck on, the faults do not come back. I now always plug in the trailer with the truck off and have had no more issues. I had one instance where the running lights did not come during the light test. I pulled the trailer plug and looked at the connections and saw that spades in each hole had been bent back like the picture linked and no longer touched at the center. I bent both spades gently toward the center in each hole until they touched. The running lights then worked when plugged in. I also clean with deoxit 5 and every third or 4th time pulling reset the spades as described Have not had an issue since. I saw some one suggest dielectric grease. I strongly recommend against this because it is intended as an electrical insulator and will reduce the contact conductivity. Deoxit 5 leaves a corrosion inhibitor behind and repels water while increasing the connection strength.
Side note, the truck will throw warnings if you try to plug in a tongue light (decorative light that plugs into the trailer harness and is put in the receiver) or if you plug in an adapter with test lights. It doesn't recognize the amount of current draw and throws faults. The same thing can happen with any decorative lights. If you're experiencing an issue, try disconnecting anything you have added and see if it goes away.
Mike Just an update from my first posting. GM has a bulletin PIT5311F It talks a lot about grounding. All that was suggested was done to our 5th wheel with no luck. Near the end it states that engineering recommends the use of a Poliak Heavy Duty 7 way plug on the trailer side. This did not work for me either. It makes no sense to me seeing the manufacturers buy trailer wiring by the thousands. I had been in touch with General Motors Executive offices. They wanted me to bring my truck and 5th wheel in and they would hook up a computer and we would drive around until there was a message on the dash. I refused. Told them to take one of their used trucks and find a small trailer with a 7 prong plug and drive. Thanks
I have a 2009 GMC Sierra 2500HD and have experienced this exact same thing multiple times. There have been times when I had no trailer braking. Fortunately it hasn't happened yet when I had been in dire need of my braking system!! This is very disturbing and we've been trying to find TSB from GM regarding this issue. It appears that GM is burying their heads in the sand regarding this issue. They MUST BE MADE ACCOUNTABLE for fixing this very serious issue!!!
I had a 2013 and it did exactly what has been described. Fortunately my trailer was only about 12k loaded but could have become an issue in the right situation. The 7 pin in the truck is aftermarket installed by hitch shop
We have experienced this warning as well, most often when starting the truck (2016 GMC 3500 Sierra HD Duramax) - happens almost every time. Since we travel with a camper on the truck pretty much 100% of the time (which is wired into the truck's 7 pin connection), the truck virtually always thinks there is a trailer attached. We also have a number of different trailers that we tow on a stinger while the camper is on, but none of them have electric brakes (the lighter ones have no brakes and the larger ones have surge brakes). Therefore, while we do get the warning, I can't tell if the electric trailer braking is affected since we never use it. Based on this, however, I would conclude that the issue is definitely with the truck, not any of the trailers (or camper).
I have a similar problem with my 2015 Ford F350 SuperDuty Lariat. Research I've done so far indicates a likely source is chafed wiring at the trailer wheel hubs or inside the axles. I haven't physically checked it out on my 5er yet, so I am extremely interested in this series.
Known issue. The trailer control module is located above the spare tire on driver side frame. Take off and clean all the connections including 7 way trailer plug as well as the module and frame where it attaches. Mine has work fine after a thorough cleaning. You may need a new module which i believe you can get at amazon. Just be careful connectong back up not to bend pins.
2016 Silverauto 3500HD, same annoying problem especially after winter storage. Finally sprayed connections with electric cleaner and wiggle the connectors aggressively and seemed to work. Have a truck camper w/stinger for towing so there are multiple connectors.
I had the same trailer brake problem on my 2017 GMC Sierra! Kept blowing the fuse in the under hood fuse compartment too.
I solved the problem by trading in the truck and buying a new 2019 Sierra with a gear upgrade that gave me an 11,200 lb towing capacity.
I'm going through this right now with my 2015 Silverado 2500HD.
I've had the "trailer disconnected" message as well as the "check right/left turn signal" messages. I have had the brakes not work but that seemed to be driven by either having the truck running when I plugged in (for some reason the 2022 GMC wants the engine off) or plugging and then replugging. Shutting the engine off and restarting it seems to correct the issue with not being recognized.
I saw a post elsewhere that there was a GM Tech bulletin that indicated the trailer plug was at fault. I had this issue on a 2013 and solved it using an EzConnector system on the truck and camper. Expensive but so much better than a Bargman plug/jack. I'll be swapping my 2022 to that as soon as the parts are available.
My 2009 GMC 2500HD 6.6 LMM regularly gives me the "Check Braking System" display where I have no trailer braking. I replaced the control module with genuine GM part and it still gives me the message. This is a serious issue and GM MUST resolve it!
My 2019 Silverado dually has never done that. I pull a tri-axle camper. I use dielectric grease on the plugs to prevent corrosion.
This has happened to my 2016 2500HD Silverado a few times. The warning comes on for a few seconds, then goes off. I am going to clean the 7 way and see if that helps. If not, I think I will change out the 7 pin receptacle.
https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.getawaycouple.com%2F7-pin-trailer-plug%2F&psig=AOvVaw32SpC9fOPf8wRqRiSub0sZ&ust=1674992014090000&source=images&cd=vfe&ved=0CA8QjRxqFwoTCLjWm9KV6vwCFQAAAAAdAAAAABAO
2022 GMC Denali 3500
I found out that if I plug in the truck while the truck is turned on, I get error messages on the trucks display that the trailer is not connected. If you turn the truck off, disconnect and reconnect the trailer plug then turn the truck on, the faults do not come back. I now always plug in the trailer with the truck off and have had no more issues. I had one instance where the running lights did not come during the light test. I pulled the trailer plug and looked at the connections and saw that spades in each hole had been bent back like the picture linked and no longer touched at the center. I bent both spades gently toward the center in each hole until they touched. The running lights then worked when plugged in. I also clean with deoxit 5 and every third or 4th time pulling reset the spades as described Have not had an issue since. I saw some one suggest dielectric grease. I strongly recommend against this because it is intended as an electrical insulator and will reduce the contact conductivity. Deoxit 5 leaves a corrosion inhibitor behind and repels water while increasing the connection strength.
Side note, the truck will throw warnings if you try to plug in a tongue light (decorative light that plugs into the trailer harness and is put in the receiver) or if you plug in an adapter with test lights. It doesn't recognize the amount of current draw and throws faults. The same thing can happen with any decorative lights. If you're experiencing an issue, try disconnecting anything you have added and see if it goes away.
check out the information on this page to see if this applies to the situation
https://www.etrailer.com/Accessories-and-Parts/Hydrastar/HBA-CAM.html
This has happened in my GMC several times. Many of them while I am not towing anything. I kinda look at the dash and ask the big question.
Mike Just an update from my first posting. GM has a bulletin PIT5311F It talks a lot about grounding. All that was suggested was done to our 5th wheel with no luck. Near the end it states that engineering recommends the use of a Poliak Heavy Duty 7 way plug on the trailer side. This did not work for me either. It makes no sense to me seeing the manufacturers buy trailer wiring by the thousands. I had been in touch with General Motors Executive offices. They wanted me to bring my truck and 5th wheel in and they would hook up a computer and we would drive around until there was a message on the dash. I refused. Told them to take one of their used trucks and find a small trailer with a 7 prong plug and drive. Thanks
I have a 2009 GMC Sierra 2500HD and have experienced this exact same thing multiple times. There have been times when I had no trailer braking. Fortunately it hasn't happened yet when I had been in dire need of my braking system!! This is very disturbing and we've been trying to find TSB from GM regarding this issue. It appears that GM is burying their heads in the sand regarding this issue. They MUST BE MADE ACCOUNTABLE for fixing this very serious issue!!!
I had a 2013 and it did exactly what has been described. Fortunately my trailer was only about 12k loaded but could have become an issue in the right situation. The 7 pin in the truck is aftermarket installed by hitch shop
We have experienced this warning as well, most often when starting the truck (2016 GMC 3500 Sierra HD Duramax) - happens almost every time. Since we travel with a camper on the truck pretty much 100% of the time (which is wired into the truck's 7 pin connection), the truck virtually always thinks there is a trailer attached. We also have a number of different trailers that we tow on a stinger while the camper is on, but none of them have electric brakes (the lighter ones have no brakes and the larger ones have surge brakes). Therefore, while we do get the warning, I can't tell if the electric trailer braking is affected since we never use it. Based on this, however, I would conclude that the issue is definitely with the truck, not any of the trailers (or camper).
I have a similar problem with my 2015 Ford F350 SuperDuty Lariat. Research I've done so far indicates a likely source is chafed wiring at the trailer wheel hubs or inside the axles. I haven't physically checked it out on my 5er yet, so I am extremely interested in this series.
Known issue. The trailer control module is located above the spare tire on driver side frame. Take off and clean all the connections including 7 way trailer plug as well as the module and frame where it attaches. Mine has work fine after a thorough cleaning. You may need a new module which i believe you can get at amazon. Just be careful connectong back up not to bend pins.
2016 Silverauto 3500HD, same annoying problem especially after winter storage. Finally sprayed connections with electric cleaner and wiggle the connectors aggressively and seemed to work. Have a truck camper w/stinger for towing so there are multiple connectors.