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 107 (HYBRID ENERGY STORAGE SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC P0AE7CIRCUIT/SYSTEM TESTING
2009 Chevrolet Tahoe Base, 4.8 C
Circuit/System Testing
2009 Chevrolet Tahoe Base, 4.8 CSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 GMC Yukon and 2008 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
- 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 .
- Remove the drive motor generator battery cover. Refer to Drive Motor Battery Case Upper Cover, Front Cover, and Right Side Cover Replacement .
- Connect the 12 volt battery.
- Disconnect X1 at the HV current limit relay. Connect a test lamp between X1 and ground. The test lamp should not illuminate.
- If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit test normal, replace the drive motor generator battery control module.
- With a scan tool, command the HV current limit relay CLOSED. The test lamp should turn ON.
- If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the drive motor generator battery control module.
- Disconnect X2 at the HV current limit relay. Connect a test lamp between X1 and X2.
- With a scan tool, command the HV current limit relay CLOSED. The test lamp should turn ON.
- If the test lamp does not illuminate, test the ground circuit for an open/high resistance and repair as required.
- Connect the X1 and X2 to the HV current limit relay.
- Connect a DMM, across X3 and X4 on the high voltage contact side of HV current limit relay. Using a scan tool, command the precharge contactor CLOSED. You should measure less than 0.5 ohms of resistance across the high voltage contact side.
- If the resistance is greater than the specified value, replace the inverter current limit 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:
- • 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.