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.
Circuit/System Testing
2009 Chevrolet Tahoe Base, 4.8 CSECTION Circuit/System Testing
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2011 GMC Yukon XL, 2011 GMC Yukon, 2011 Chevrolet Tahoe, 2011 Chevrolet Suburban, and 2011 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
- Front impact sensor
- SDM module
- Front impact sensor wiring harness connector
- SDM wiring harness connector
- Ignition OFF, disconnect the front impact sensor harness connector.
- Remove the SDM harness connector.
- Test for infinite resistance between the front impact sensor signal circuit terminal 1 and ground.
- If less than the specified value, test the circuit for a short to ground.
- Ignition ON, test for less than 1 volt between the front impact sensor signal circuit terminal 1 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 impact sensor low reference circuit terminal 2 and ground.
- If greater than the specified range, test the circuit for a short to voltage.
- Test for less then 1 ohm between the front impact sensor signal circuit terminal 1 and the SDM terminal.
- If greater than the specified range, test the circuit for an open/high resistance.
- Test for less then 1 ohm between the front impact sensor low reference circuit terminal 2 and the SDM terminal.
- If greater than the specified range, test the circuit for an open/high resistance.
- If the circuits test normal, replace the appropriate front impact sensor.
- Reconnect all SIR components. Ignition ON, with a scan tool clear and recheck for DTCs.
- If the front impact sensor DTC returns and is current, replace the SDM.
IMPORTANT:
When removing connectors, inspect for damage or corrosion. Damage or corrosion in the following requires repair or replacement of the affected component/connector:
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.