jonpc

I got the updated part installed last Thursday and removed the previously installed diode and did a 200+ mile drive with ZERO issues. Looks like the updated brake controller finally fixed the issue. For the sake of everyone reading, there were 2 solid solutions that worked without issue, and 1 potential solution. Solution 1: Installed Diode on the 12v charge wire (Black) from the Truck to trailer. This prevented all back feeding and worked for long drives without issue. Solution 2: GM installed new Brake Controller. Took them less then 1 hour for the install. They did have to order the part which took a couple days. Was fully covered by warranty. Ideal Alternative Solution until you get GM installed updated Brake Controller: I purchased the Curt Echo Mobile Bluetooth brake controller. This is put inline with the trailer plug and bypasses the trucks brake controller. You can control sensitivity and gain using a mobile app, and can even have a manual brake button on the phone. I drove 2k+ miles using this setup. I was very annoyed that I needed to use this adapter on a brand new 2024 3500 GMC, and lost the ability to control gain and manual braking with the in-truck controls, but it was better to have reliable brakes when I was going through a lot of mountains. Potential Solution: I attempted a drive with all 12v accessories turned on in the trailer while driving. Fans, Lights, Fridge, etc. This was an attempt to keep the charge on the batteries low enough that the back feeding would not occur. It worked for about an hour before the 550watts of solar was charging faster then the usage. This may be a viable solution for trailers with little or no solar.

Went to the GMC dealer for service yesterday and asked about the bulletin and if they had updated info from GM. Got them to print out the new updated bulletin. Looks like they added in some 2023 models to the list. Correction for the issue is listed as "Replace the trailer brake module with updated part", and lists the part number as 23306694 for (Sierra HD) which matches the 2023 brake controller. I had them order the part and will have them put it in when it arrives.

The diode was installed on the 12v hot wire. The brake cable is left untouched. On my rig the wire was black (12 v). Did another 300 miles today and did notice that the truck gives a message that the gain control setting was not saved when the truck was started. I am guessing the diode may be interfering with the saved settings of the gain control. However the gain 4.5 was still set whenever the error message shows. I manually engage the trailer brakes before moving and still have had no issues before the message.

I installed the diode inline with the trailer plug and it worked perfectly. Did not receive a single check trailer wiring message on a 400+ mile drive. On previous drives the message would occur as soon as the trailer batteries charged via solar and converter. I found that if I turned on everything in the trailer, it would eat up battery and would be a temporary fix until the solar generated more then the usage. I have 600 watts of solar so it would normally throw the error after 30 minutes of sunlight. With the diode installed, I had no issues. I will see if gmc will swap the brake controller to the 2023 version during next service. For now this is a viable solution for reliable brakes.