I've just installed a kenwood system in my clk and experienced exactly the same problem. Connected it up, it made a wirring sound then nothing.
I only solved the problem when I used a multimeter to identify which wire did what.
I had been misled by another website which suggested that the red/green wire was switched, it turned out it doesn't seem to do anything.
I knew there was some unused wiring in the recess where the radio fits and found a red wire not connected to anything. Tested it with my multimeter, hurrah the elusive switched wire. Two minutes later everything was up and running.
I only solved the problem when I used a multimeter to identify which wire did what.
I had been misled by another website which suggested that the red/green wire was switched, it turned out it doesn't seem to do anything.
I knew there was some unused wiring in the recess where the radio fits and found a red wire not connected to anything. Tested it with my multimeter, hurrah the elusive switched wire. Two minutes later everything was up and running.
