08 silverado 3500 has no connection to trailer brakes (all…

OK, so there probably are codes, but you can't access them.

This is a tough diagnosis without the trouble code to tell us what the computer is complaining about, a lot tougher than it has to be. I can give you a schematic, and you can trace the brake wiring, power and ground circuits, things like that, but without knowing exactly why the TBC is turning on that message, it's all just a crapshoot, and hoping to come up with the right answer by accident.

$50 worth of diagnosis time at a local repair shop would have saved you many times that much money already, since you've replaced parts that didn't need to be replaced. If this were in my shop, I wouldn't attempt a diagnosis on this without at least knowing the trouble code, and there is other really pertinent data that can be gained from a good scan tool.

I'll give you the schematic if you like, but I really recommend having this looked at by someone with the right scan tool to get these answers.

You're welcome, let me know what you find there, and I can get you all the resources you need.

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