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 CARSECTION 428 (HYBRID/EV CONTROL SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC P1AF0 OR P1AF2CIRCUIT/SYSTEM VERIFICATION
2009 Chevrolet Tahoe Base, 4.8 C
Circuit/System Verification
2009 Chevrolet Tahoe Base, 4.8 CSECTION Circuit/System Verification
WARNING: This page is about a different car, the 2011 GMC Yukon, 2011 Chevrolet Tahoe, and 2011 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.
- Verify that DTC P1AE7 is not set.
- If the DTC is set, refer to DTC P1AE6 or P1AE7 .
- Verify that DTCs P0A78, P0A79, P0BFD, P0BFE, P0C01, or P0C04 is not set.
- If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- Ignition ON, engine OFF, observe the scan tool battery energy control module contactor system status parameter. The status should display closed.
- If not the specified value, refer to Symptoms - Hybrid Controls .
- Hood closed, transmission in park, and Ignition OFF for at least 2 minutes.
- Ignition ON, engine OFF, within 5 seconds of ignition ON, observe the hybrid powertrain control module 300V Circuit parameter and compare it to both data parameters listed below. Each motor parameter should be within 20 V of the hybrid powertrain control module 300 V circuit parameter.
- Motor 1 Isolation Voltage
- Motor 2 Isolation Voltage
- If only one Motor Isolation Voltage value is not within the specified range, replace the drive motor generator power inverter control module.
- If both Motor Isolation Voltage values are not within the specified range, refer to DC Circuit Testing in Circuit/System Testing.
- If both Motor Isolation Voltage values are within the indicated range, a loss of isolation condition is not currently present, refer to AC Circuit Testing in Circuit/System Testing.
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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.