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 MANUALSCHEVROLET2008CHEVY EXPRESS G3500, VAN PASSENGER EXTENDEDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 181 (CELLULAR SYSTEM, ENTERTAINMENT SYSTEM, AND NAVIGATION SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESONSTAR ONE OR MORE BUTTONS INOPERATIVECIRCUIT/SYSTEM TESTING
2008 Chevrolet Chevy Express G3500, Van Passenger Extended
Circuit/System Testing
2008 Chevrolet Chevy Express G3500, Van Passenger ExtendedSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT:
Contact the OnStar® Call Center first before pressing the emergency button in order to notify them of the test.
- Ignition OFF, disconnect the harness connector at the inside rearview mirror.
- Ignition OFF, doors closed, interior lamps OFF, test for less than 5 ohms between the inside rearview mirror ground circuit terminal 8 and ground.
- If greater than specified range, test the ground circuit for an open/high resistance.
- Ignition ON, test for 9.5-10.5 volts between the keypad supply voltage circuit terminal 12 and ground.
- If less than specified range, test the voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the VCIM.
- If greater than specified range, test the voltage supply circuit for a short to voltage. If the circuit tests normal, replace the VCIM.
- Test for less than 1 volt between the keypad signal circuit terminal 11 ground.
- If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the VCIM.
- Test for 9.5-10.5 volts between the keypad supply voltage circuit terminal 12 and the keypad signal circuit terminal 11.
- If not within the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the VCIM.
- Ignition OFF, disconnect the X1 harness connector at the VCIM.
- Ignition OFF, test for infinite resistance between the keypad signal circuit terminal 11 and ground.
- If less than the specified value, test the signal circuit for a short to ground.
- If all circuits test normal, replace the inside rearview mirror.
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.