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 G2500, VAN CARGO, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 989 (SUPPLEMENTAL INFLATABLE RESTRAINT SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC B0091CIRCUIT/SYSTEM TESTING
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6
Circuit/System Testing
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Circuit/System Testing
WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT:
When removing connectors, inspect for damage or corrosion. Damage or corrosion in the following requires repair or replacement of the affected component/connector:
- The front end sensor
- The SDM module
- The front end sensor wiring harness connector
- The SDM wiring harness connector
- Ignition OFF, disconnect the appropriate front end sensor connector. Refer to Front End Sensor Replacement for location of connector.
- Remove the SDM connector. Refer to SDM replacement for location of connector.
- Test for infinite resistance between the signal circuit and ground.
- If less than infinite resistance, test the circuit for a short to ground.
- Ignition ON, test for less than 1 volt between the front end sensor signal circuit and ground.
- If greater than the specified range, test the circuit for a short to voltage.
- Ignition ON, test for less than 1 volt between the front end sensor low reference circuit and ground.
- If greater than the specified range, test the circuit for a short to voltage.
- Test for less then 1 ohm of resistance between the signal circuit front end sensor connector and SDM connector.
- If greater than the specified range, test the circuit for an open/high resistance.
- Test for less then 1 ohm of resistance between the low reference circuit front end sensor connector and SDM connector.
- If greater than the specified range, test the circuit for an open/high resistance.
- If the circuits test normal, replace the appropriate front end sensor.
- Reconnect all SIR components. Ignition ON, with a scan tool clear and recheck for DTCs.
- If the front end sensor DTC returns and is current, replace the SDM.
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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.