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Test Description

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2002 GMC Yukon XL, 2002 GMC Yukon, 2002 Chevrolet Tahoe, 2002 Chevrolet Suburban, and 2002 Cadillac Escalade EXT. However, it is still accessible from the selected car via links, so may be relevant.

The number below refers to the step number on the diagnostic table.

  1. 2:  This step checks that the VIU is sending out the proper supply voltage.
DTC B2476

Step Action Value(s) Yes No
Schematic Reference: OnStar Schematics 
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 OFF.
  2. Disconnect the OnStar® button assembly connector.
  3. Turn the ignition ON, 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 4  Go to Step 3 
3 Test the Keypad Supply Voltage circuit for an open or short to ground. Refer to CIRCUIT TESTING and WIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 11  Go to Step 8 
4 Test the Keypad Supply Voltage circuit for a short to voltage. Refer to CIRCUIT TESTING and WIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 11  Go to Step 5 
5 Test the keypad ground circuit for an open. Refer to CIRCUIT TESTING and WIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 11  Go to Step 6 
6 Test the Keypad Signal circuit for a short to voltage. Refer to CIRCUIT TESTING andWIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 11  Go to Step 7 
7 Inspect for poor connections at the harness connector of the OnStar® button assembly. Refer to TESTING FOR INTERMITTENT 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 VIU. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS and CONNECTOR REPAIRS .
Did you find and correct the condition?		 - Go to Step 11  Go to Step 10 
9 Replace the OnStar® button assembly. Refer to OnStar Button Assembly Replacement (Utility) .
Did you complete the replacement?		 - Go to Step 11  -
10
IMPORTANT: Perform the OnStar(R) setup procedure.
Replace the VIU. Refer to OnStar Vehicle Interface Unit (VIU) Replacement .Did you complete the replacement?		 - Go to Step 11  -
11
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?		 - Go to Step 2  System OK
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