2002 Trailblazer / GMC Envoy Owners
But there is a work around: The head unit sends its audio to the amps at a constant level, and the amp's volume is digitally controller via the Databus. So you can do this: Wire up a relay switch to toggle between your own input and the radio's output.
24-pin connector:
A9 - Left (-) dk green
A8 - Left (+) tan
B10 - Right (-) org / blk
B11 - Right (+) lt green
You MUST use a ground loop isolator and 2 DPDT relays so that you are completely disconnecting all 4 wires from the head unit and connecting them to your own input.
Radio Left (-) ----/--- Amp Left (-)
Radio Left (+) ----|/-- Amp Left (+)
Radio Right (-) ---||/-- Amp Right (-)
Radio Right (+) ---|||/-- Amp Right (+)
In L (-) ---|************| -- To Amp L (-)
In L (+) ---|GND Isolator| -- To Amp L (+)
In R (-) ---|************| -- To Amp R (-)
In R (+) ---|************| -- To Amp R (+)
I tried it out and it works great! It's a little tight to splice the factory harness, but it does the trick.
-hj

