GMCJeff

I was having the trailer disconnected message frequently on my 2020 sierra. Noticed that during a trailer light test, that a relay was clicking near the hitch on the truck. It was coinciding with the disconnected notification. So I set out to check exactly when the disconnect notification occurred in conjunction with every ltg condition. I found that when the tail lights were on, either turn signal caused the disconnect notification. ( Turn signal denergizes tail lamp during the flash) So upon googling I came across a GM bulletin that showed the trailer control module uses the tail lamp circuit to monitor weather a trailer is present! It has a high enough wattage threshold that may or may not be met by low draw LED bulbs. My camper is a pre LED era model, and when I first bought it had upgraded all lamps to improve efficiency and eliminate the heat. So I swapped out the 1157 tail bulbs to incandescent originals and Wallah....the issue is resolved. Attached below is the GM info. I hope this helps some folks. GM needs to fix this issue. Obviously the engineers set the trailer monitor wattage threshold too high to allow for the lighter LED wattage. It causes a potentially dangerous condition as it disables trailer brakes and lights when it occurs. https://static.nhtsa.gov/odi/tsbs/2022/MC-10208985-9999.pdf

I was having the trailer disconnected message frequently on my 2020 sierra. Noticed that during a trailer light test, that a relay was clicking near the hitch on the truck. It was coinciding with the disconnected notification. So I set out to check exactly when the disconnect notification occurred in conjunction with every ltg condition. I found that when the tail lights were on, either turn signal caused the disconnect notification. ( Turn signal denergizes tail lamp during the flash) So upon googling I came across a GM bulletin that showed the trailer control module uses the tail lamp circuit to monitor weather a trailer is present! It has a high enough wattage threshold that may or may not be met by low draw LED bulbs. My camper is a pre LED era model, and when I first bought it had upgraded all lamps to improve efficiency and eliminate the heat. So I swapped out the 1157 tail bulbs to incandescent originals and Wallah....the issue is resolved. Attached below is the GM info. I hope this helps some folks. GM needs to fix this issue. Obviously the engineers set the trailer monitor wattage threshold too high to allow for the lighter LED wattage. It causes a potentially dangerous condition as it disables trailer brakes and lights when it occurs. https://static.nhtsa.gov/odi/tsbs/2022/MC-10208985-9999.pdf