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.
Test Description
The number below refers to the step number on the diagnostic table.
- 2: This step tests the at rest state of the keypad signal circuit.
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: OnStar Schematics Connector End View Reference: Cellular Communication Connector End Views |
||||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | - | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 |
|
0 V | Go to Step 3 | Go to Step 4 |
| 3 | Test the keypad signal circuit for a short to voltage or high resistance. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 9 | Go to Step 5 |
| 4 | Test the keypad supply voltage circuit for an open or short. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 9 | Go to Step 6 |
| 5 | 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 9 | Go to Step 7 |
| 6 | Inspect for poor connections at the harness connector of the 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 9 | Go to Step 8 |
| 7 | Replace the OnStar® button assembly. Refer to OnStar Button Assembly Replacement . Did you complete the replacement? |
- | Go to Step 9 | - |
| 8 | Replace the VCIM. Refer to Control Module References
in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? |
- | Go to Step 9 | - |
| 9 |
|
- | Go to Step 2 | System OK |
Use the Manual With the Right Hardware
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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.
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