Diagnostic Instructions
Circuit/System Verification
Ignition ON, With the scan tool command the VCIM to turn on the red and green LED.
⇒ | If the red or green LED indicators do not illuminate, go to Circuit/System Testing. |
Reference Information
Schematic Reference
OnStar Schematics
Connector End View Reference
Entertainment/Communication Connector End Views
Description and Operation
OnStar Description and Operation
Electrical Information Reference
Circuit/System Verification
Ignition ON, With the scan tool command the VCIM to turn on the red and green LED.
⇒ | If the red or green LED indicators do not illuminate, go to Circuit/System Testing. |
Circuit/System Testing
- Ignition OFF, disconnect the inside rearview mirror harness connector .
- Ignition ON, test for 9.2 to 10.2 volts on the keypad supply voltage circuit.
⇒ | If less than the specified voltage repair short to ground or open or replace the VCIM. |
- Test for less than 1 ohm between the inside rearview mirror harness connector terminal 8 and ground.
⇒ | If greater than specified value repair open or high resistance. |
- Connect a DMM between the inside rearview mirror harness connector terminal 14 and ground. With a scan tool command the green LED ON. Verify 9.2 to 10.2 volts is present with the green LED commanded ON.
⇒ | If 9.2 to 10.2 volts is present with the green LED is commanded ON, replace the inside rearview mirror. |
- Connect a DMM between the inside rearview mirror harness connector terminal 15 and ground. With a scan tool command the red LED ON. Verify 9.2 to 10.2 volts is present with the red LED commanded ON.
⇒ | If 9.2 to 10.2 volts is present with the red LED is commanded ON, replace the inside rearview mirror. |
- Disconnect the VCIM harness connector C1.
- Test for less than 1 volt between the C1 VCIM connector terminal 3 and the inside rearview mirror harness connector terminal 14.
⇒ | If more than the specified value repair short to voltage on the keypad green LED signal circuit. |
- Test for less than 1 volt between the C1 VCIM connector terminal 2 and the inside rearview mirror harness connector terminal 15.
⇒ | If more than the specified value repair short to voltage on the keypad red LED signal circuit. |
- Test for less than 1 ohm between the C1 VCIM connector terminal 3 and the inside rearview mirror harness connector terminal 14.
⇒ | If more than the specified value repair open or high resistance on the keypad green LED signal circuit. |
- Test for less than 1 ohm between the C1 VCIM connector terminal 2 and the inside rearview mirror harness connector terminal 15.
⇒ | If more than the specified value repair open or high resistance on the keypad red LED signal circuit. |
- If all circuits test normal, test or replace the VCIM.
Repair Instructions
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.