2020 Silverado 3500 - Limp mode, trailer issue or not?

[92saturnsl2]

I was helping a co-worker rewire a tandem axle gooseneck trailer that has four brake actuators on it. Simple enough job, we completely rewired all four from front to back and tested them, but only three engage the brake despite verifying power @ all brake actuators.

First couple times taking the trailer out, no issues other than the single non-working brake. On the last trip of the day (load 3), truck entered limp mode with the following dash errors: ESC, ABS, Traction control, trailer something or other disabled, and reduced power which limited speed to 10mph or so.

When I read the codes I got two rear wheel speed sensor DTCs. Owner wanted to attribute this to the trailer re-wiring we did, but I'm not convinced. Nothing magical about wiring trailer brakes. I reset the codes and truck has been running fine, but it's been running empty and we haven't tried hooking the trailer back up yet. Only thing I can think of is perhaps the one non-functioning trailer brake is drawing too much current... but can't see how that would be related to a WSS DTC.

Could any of this be related, or what is the possibility of a random fluke? This is a 2020 6.6L 4x4 DRW Silverado 3500.

 

[weaponoffreedom]

perhaps the one non-functioning trailer brake is drawing too much current...

I think you are on the right track, if it is the trailer. Or maybe brake shoes need adjustment. If they are too far out, they can draw too much and make these over computerized messes, mess up.

 

[92saturnsl2]

I think you are on the right track, if it is the trailer. Or maybe brake shoes need adjustment. If they are too far out, they can draw too much and make these over computerized messes, mess up.

That's along the lines of what I was thinking. In the old days it just popped a fuse and you knew exactly what to look for.

I'm going to unplug the front axle brakes for more testing. If the trailer goes down the road, rear brakes work good and doesn't cause issues with the truck, I'll plug the front back in, starting with the one on the front axle I know is working. If I plug the fourth in and the truck goes haywire, I'll have it narrowed down.

Next weekend after this run of deliveries is over, I'll dig into the actual brakes. Does anyone know what a normal working trailer brake magnet should measure for resistance?

 

[weaponoffreedom]

keep me posted and good luck