Ignition OFF, you need to disconnect the X1 harness connector at the CCSM, verify that a test lamp illuminates between the ground circuit terminal M and B+, verify that a test lamp illuminates between the B+ circuit terminal E and ground, and disconnect the X2 harness connector at the CCSM. Ignition ON, you can verify that a test lamp illuminates between the ignition circuit terminal 1 and the ground. If all circuits test normal, replace the CCSM.