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 following number(s) refer to the step(s) on the diagnostic table.
- 3
Determines if the OnStar® status LED has the necessary GRN LED signal circuit.
- 5
If the GRN LED signal is shorted to voltage then the OnStar® three button assembly has been damaged. The OnStar® three button assembly has to be replaced.
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| Schematic Reference: OnStar Schematics DEFINITION: OnStar® LED is inoperative. This procedure is for diagnosing problems with the OnStar® button assembly. |
||||
| 1 | Did you perform the OnStar® Diagnostic System Check? | - | Go to Step 2 | Go to Diagnostic System Check - Cellular Communication |
| 2 |
|
- | Go to Testing for Intermittent Conditions and Poor Connections , and Connector Repairs in Wiring Systems | Go to Step 3 |
| 3 |
|
7-9 V | Go to Step 6 | Go to Step 4 |
| 4 | Test the keypad GRN LED signal circuit for an open, high resistance or a short to ground. Refer to Circuit Testing
, and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 10 | Go to Step 5 |
| 5 | Test the keypad GRN LED signal circuit for an short to voltage. Refer to Circuit Testing
, and Wiring Repairs
. Did you find and correct the condition? |
- | Go to Step 7 | Go to Step 8 |
| 6 | Inspect for poor connections at the harness connector of the rear view mirror or 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 10 | Go to Step 7 |
| 7 | Replace the rear view mirror or the OnStar® button assembly. Refer to Inside Rearview Mirror Replacement
, or OnStar Button Assembly Replacement (Pick-Up) , OnStar Button Assembly Replacement (Utility) . Did you complete the repair? |
- | Go to Step 10 | - |
| 8 | Inspect for poor connections at the harness connector of the VIU. 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 10 | Go to Step 9 |
| 9 |
IMPORTANT:
Replace the vehicle interface unit (VIU). Refer to OnStar Vehicle Interface Unit Replacement .Did you complete the repair?Perform the OnStar® setup procedure. |
- | Go to Step 10 | - |
| 10 | Operate the system in order to verify the repair. Did you correct the condition? |
- | System OK | Go to Step 2 |
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.