1997 GMC K2500 Suburban - no brakes in tow harness

Thanks DavisK,

I have the service manual and I showed in my original post how the manual says they're supposed to work, but there are no brake signals in those two wires on my vehicle. This is the problem.

My service manual is on CD and I scanned the CD looking for some special relay that might be in question but the only thing could find was the TCC/StopSwitch for the Suburban on the brake pedal and it seems to work fine since brake lights are ok and cruise disconnect is ok.