Without OnStar®
WARNING: This page is about a different car, the 2007 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the harness connector at the rearview mirror.
- Ignition ON, test for greater than 9 volts between the terminal 2 and ground.
- If less than specified value, test the cellular microphone signal circuit for an ope/high resistance, for a short to ground, or for a short to the drain wire. If the circuit tests normal, test or replace the radio.
- Test for greater than 9 volts between the terminal 2 and the terminal 10.
- If less than specified value, test the drain wire for an open/high resistance. If the circuit tests normal, test or replace the radio.
- If all circuit test normal, replace the rearview mirror assembly.