GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

Schematic Reference: OnStar Schematics

Connector End View Reference: Entertainment/Communication Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Important: Contact the OnStar® Call Center first before pressing the emergency button in order to notify them of the test.

  1. Turn ON the ignition, with the engine OFF.
  2. Press each OnStar® button one at a time.

Are all buttons inoperative?

--

Go to Step 4

Go to Step 3

3

Are any buttons intermittent or inoperative?

--

Go to Step 7

Go to Testing for Intermittent Conditions and Poor Connections

4

  1. Turn OFF the ignition.
  2. Disconnect the rear view mirror.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the keypad supply voltage circuit to a good ground.

Does the voltage measure greater than the specified value?

9 V

Go to Step 6

Go to Step 5

5

Test the keypad supply voltage circuit for an open or short. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 11

Go to Step 8

6

Test the keypad signal circuit for an open or short . Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 11

Go to Step 9

7

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 11

Go to Step 9

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 11

Go to Step 10

9

Replace the rearview mirror. Refer to Inside Rearview Mirror Replacement .

Did you complete the replacement?

--

Go to Step 11

--

10

Important: Perform the OnStar® setup procedure.

Replace the VCIM. Refer to Communication Interface Module Replacement .

Did you complete the replacement?

--

Go to Step 11

--

11

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2