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 1076 (CELLULAR COMMUNICATION SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC B2476: CELLULAR PHONE SELECT SERVICE SWITCH MALFUNCTION (3 BUTTON ASSEMBLY)TEST DESCRIPTION
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Test Description
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Test Description
WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. 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 Vehicle Communication Interface Module is sending out the proper supply voltage.
DTC B2476
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: OnStar Schematics Connector End View Reference: Cellular Communication Connector End Views |
||||
| 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
in Wiring Systems. 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
in Wiring Systems. 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
in Wiring Systems. 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
and Wiring Repairs
in Wiring Systems. 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 Conditions and Poor Connections
and Connector Repairs
in Wiring Systems. 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
in Wiring Systems. 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 . 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 |
|
- | Go to Step 2 | System OK |
RENDER: 1.0x
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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.