Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1604 (CELLULAR COMMUNICATION SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC B2476TEST DESCRIPTION
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Test Description
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION 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.
- 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 |
|
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 |
|
- | Go to Step 2 | System OK |
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.