I bought my 02 Duramax used and hauled a 32' 5er over 5000mi.I had some trouble with the brakes on the trailer as the controller wouldn't change from from amber to red.
To check the brakes on the trailer I squeezed the handle on the controller.The trailer stopped the rig with it's brakes but the light never turned on.I looked at the plug on both ends to see if any of the wires were touching.One wire was touching but this didn't solve the problem.
Now that we're home I looked at the back brakes on the truck and it was metal to metal.The front brakes are good.I'm thinking that this may be normal for 70K.It's eather that or I've been stopping the rig with no brakes
working on the trailer. Any Thoughts!!!

Judging from the rear brake job I just did, I would venture to say that the rear brakes are pretty heavily biased and are wearing quicker than the front - which is opposite of a normal passenger vehicle. I managed to catch things before they were down to bare metal, but my rotors were toast.

It sounds like your controller has not been engaging the trailer brakes suffieciently. My controller lets me adjust the bias on the trailer with a slider - I usually do this after i get up to speed and apply the brakes. I move the slider until I feel the trailer brakes really start to kick in - then I back it off a bit. Another thing that my controller has is an adjustment to "level" it depending on it's physical position - it sets up the internals for correct momentum sensing. In order for it to work correctly, that adjustment must be made otherwise it will over compensate or not engage at all when pushing on the brake pedal.

Just my $.02.