08 Silverado 3500 Factory Trailer Brake Controller

[Pocho86]

Got a issue with the trailer brakes here. On the cluster it shows the trailer brakes and gain but when I press the brake pedal or squeeze the small trailer brake controller handle to manually apply trailer brakes the gain bar does not respond. Not sure if it needs to be hooked up to a trailer for it to work. I've checked the fuses and found a few trailer turn signal related fuses blown. Put my volt meter on the white and blue at the trailer plug and .5v flickering voltage and when I squeeze the manuals levers or press the brake there is not voltage change either.

 

Any help or advice would be appreciated

[newdude]

Most common failures on those systems are the relay (mounted on the frame), brake pedal position sensor (but chances are your cruise won't work right) and the trailer plug. Does the DIC say "Service Trailer Brake"?

[Pocho86]

No it does not

[davester]

I'm pretty sure a trailer with a brake system needs to be hooked up before that stuff is enabled.

[Formulabruce]

I'm pretty sure a trailer with a brake system needs to be hooked up before that stuff is enabled.

This is the answer. The trailer brakes are a ground, BUT the controller controls the ground side. That said; I doubt you'll see much more than a logic voltage at Blue till its plugged in. Obviously there will be NO gain if the unit cant determine the resistance needed in the circuit.

[Pocho86]

I understand but it should still be able to produce an output signal whether there is a trailer connected or not, all Dodge trucks including the two I have produce a gain signal whether there is a trailer hooked up or not. Maybe the way this particular truck is set up it needs to have a trailer connected I don't know

[davester]

maybe dodge uses an older or cheaper setup? It's my understanding that, at least on my truck, the truck tests the resistance for the brakes, and if it's not the 1 or 2 ohms (I think it's that, depending on if you have 1 or 2 axles), it'll disable the system and report a problem with the brakes, and if it's open, it doesn't do anything. It might be so you don't get fooled into thinking the trailer brakes are working when they aren't (like if the TBC shows that it's applying brakes, but the brake connection is really open).

 

If you want to test it, you could try hooking up a resistor with the right value and wattage and then see how much power is put through it.

[Chevor]

If trailer is hooked up and no brakes:

Usually changing the 30 amp stud 2 fuse fixes this...though fuse never looks blown.