For 1990-2009 cars

#### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. Determines if the OnStar® status LED has the necessary GREEN LED signal circuit voltage.

2. If the GREEN LED signal is shorted to voltage then the OnStar® 3-button assembly has been damaged and the OnStar® 3-button assembly must be replaced.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: OnStar Schematics Connector End View Reference: Cellular Communication Connector End Views DEFINITION: This procedure is for diagnosing problems with the OnStar® button assembly LED.
1 | Did you perform the Cellular Communications Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check - Cellular Communication
2 |

1. Turn the ignition ON, with engine OFF.
2. Observe the OnStar® status LED.

Did the OnStar® status LED turn GREEN?

--

Go to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems

Go to Step 3

3 | Measure the voltage from the keypad GREEN LED signal circuit to a good ground. Does the voltage measure near the specified value? | 7 V | Go to Step 6 | Go to Step 4
4 | Test the keypad GREEN LED signal circuit for an open, high resistance or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 5
5 | Test the keypad GREEN LED signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 7 | Go to Step 8
6 | Inspect for poor connections at the harness connector of the rearview mirror. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 7
7 | Replace the rearview mirror. Refer to Inside Rearview Mirror Replacement in Stationary Windows. Did you complete the repair? | -- | Go to Step 10 | --
8 | Inspect for poor connections at the harness connector of the vehicle communication interface module (VCIM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 9
9 | Important: Perform the OnStar® setup procedure. Replace the VCIM. Refer to Communication Interface Module Replacement . Did you complete the repair? | -- | Go to Step 10 | --
10 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2