GM Service Manual Online
For 1990-2009 cars only

Test Description

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

  1. This step 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 must be replaced.

Step

Action

Values

Yes

No

Schematic Reference: OnStar Schematics

Connector End View Reference: Entertainment/Communication Connector End Views

DEFINITION: This procedure is for diagnosing problems with the OnStar® button assembly LED.

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

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

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 .

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 .

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 .

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 .

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 .

Did you find and correct the condition?

--

Go to Step 10

Go to Step 9

9

Replace the VCIM. Refer to Control Module References .

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