What I looked at was instrument cluster illumination. In the diagram, the orange wire with yellow tracer is voltage, comes from the bcm.
The black wire with orange tracer is a constant chassis ground. One way to check a chassis ground, is to use a test lite connected to battery voltage, The other end of test lite, touch the terminal for the black wire with orange tracer, if the lite comes on bright, the ground is good.
Can you check bcm trouble codes? Some of the national brand auto stores will check codes for free.
There are other circuits that use the same ground, but, they are wired in parallel, not sure I spelled that correctly. Your radio shouldn't be a problem as far as ground.
Tuesday, August 13th, 2013 AT 10:31 AM