Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Keypad 10 Volt Reference | B2476 | B2476 | B2476 | -- |
Keypad Signal | 3 | 3 | -- | -- |
Green LED Control | 1 | 1 | 2 | -- |
Red LED Control | 1 | 1 | 2 | -- |
Inside Rearview Mirror Ground | -- | 1 | -- | -- |
1. OnStar® LED Inoperative 2. LED Illuminated At All Times 3. OnStar® Buttons Inoperative | ||||
Circuit Description
The OnStar® status LEDs are located with the OnStar buttons on the inside rearview mirror. The green LED is illuminated when the system is ON and operating normally. When the green LED is green and flashing, it is an indication that a call is in progress. When the red LED is illuminated, a system malfunction is present. In the event there is a system malfunction and the OnStar® system is still able to make a call, the LED will flash red during the call. The OnStar® LEDs are controlled by the vehicle communication interface module (VCIM) via the green LED control circuit and the red LED control circuit.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
OnStar Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON, command the Green LED ON and OFF with a scan tool while observing the green LED on the inside rearview mirror. The green LED should turn ON and OFF when commanded.
- Command the red LED ON and OFF with a scan tool while observing the red LED on the inside rearview mirror. The red LED should turn ON and OFF when commanded.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the inside rearview mirror.
- Doors closed, courtesy lamps OFF, test for less than 5 ohms between the ground circuit terminal 8 and ground.
- Ignition ON, command the green LED OFF with a scan tool. Test for less than 1 volt between the control circuit terminal 14 and ground.
- Command the green LED ON with a scan tool. Test for greater than 9 volts between the control circuit terminal 14 and ground.
- Command the red LED OFF with a scan tool. Test for less than 1 volt between the control circuit terminal 15 and ground.
- Command the red LED ON with a scan tool. Test for greater than 9 volts between the control circuit terminal 15 and ground.
- If all circuits test normal, test or replace the inside rearview mirror.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the VCIM. |
| ⇒ | If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the VCIM. |
| ⇒ | If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the VCIM. |
| ⇒ | If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the VCIM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for VCIM replacement, setup, and programming |
