GM Service Manual Online
For 1990-2009 cars only

Test Description

This procedure is for diagnosing problems with the OnStar® button assembly. The following numbers refer to the steps in the table.

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

  2. If the GRN LED signal is shorted to voltage then the OnStar® three button assembly has been damaged. The OnStar® three button assembly has to be replaced.

Step

Action

Value(s)

Yes

No

1

Did you perform the OnStar® Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Cellular Communication

2

  1. Turn the ignition ON, with ignition 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

  1. Turn the ignition OFF.
  2. Disconnect the OnStar® Keypad assembly.
  3. Turn the ignition ON, with ignition OFF.
  4. Measure the Keypad GRN LED signal circuit voltage.

Does the voltage measure near the specified value?

7v-9v

Go to Step 6

Go to Step 4

4

Test the keypad GRN 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 GRN LED signal circuit for an 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 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 Cellular Communications.

Did you complete the repair?

--

Go to Step 10

--

8

Inspect for poor connections at the harness connector of the VIU. 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

Replace the vehicle interface unit (VIU). Refer to OnStar Vehicle Interface Unit Replacement in Cellular Communications.

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