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 MANUALSCHEVROLET2009TAHOE BASE, 4.8 CREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 21 (HYBRID COOLING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC P0BC1COMPONENT TESTING
2009 Chevrolet Tahoe Base, 4.8 C
Component Testing
2009 Chevrolet Tahoe Base, 4.8 CSECTION Component Testing
WARNING: This page is about a different variant/trim than selected.
Fan Relay Test
- Identify how to disable high voltage.
- Identify how to test for the presence of high voltage.
- Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.
- Ignition OFF, disable the high voltage at the drive motor generator battery. Refer to High Voltage Disabling .
- Ignition OFF, disconnect the drive motor generator battery vent fan relay.
- Test for 85-110 Ξ© between terminals 1 and 2.
- If not within the specified range, replace the relay.
- Test for infinite resistance between the following terminals:
- 1 and 3
- 1 and 4
- 2 and 3
- 3 and 4
- If not the specified value, replace the relay.
- Install a 5 A fused jumper wire between relay terminal 2 and 12 V. Install a jumper wire between relay terminal 1 and ground. Test for less than 2 Ξ© between terminals 3 and 4.
- If greater than the specified range, replace the relay.
WARNING:
Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.
The High Voltage Disabling procedure will perform the following tasks:
Failure to follow the procedures exactly as written may result in serious injury or death.
The High Voltage Disabling procedure will perform the following tasks:
Failure to follow the procedures exactly as written may result in serious injury or death.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.