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 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.
- Ignition OFF, disconnect the transmission X176 24-way harness connector.
- Connect DT-48493 jumper harness.
- Ignition ON, test the jumper harness side for less than 8 ohms between the low reference circuit terminals listed below and ground for the appropriate drive motor generator:
- Drive motor 1 low reference circuit terminal 19
- Drive motor 2 low reference circuit terminal 23
- If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the T6 drive motor generator power inverter module.
- Ignition ON, verify the scan tool motor temperature sensor parameter is greater than 4.42 V.
- If less than the specified value, test the motor temperature sensor signal circuit for a short to ground. If the circuit tests normal, replace the T6 drive motor generator power inverter module.
- Install a 3-amp fused jumper wire between the signal circuit terminal and the low reference circuit terminal listed below for the appropriate drive motor generator. Verify the scan tool motor temperature sensor parameter is less than 0.29 V:
- Drive motor 1 terminals 13 and 19
- Drive motor 2 terminals 22 and 23
- If greater than the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the T6 drive motor generator power inverter module.
NOTE:If a short to voltage is found, test the motor temperature sensor for damage.
- Ignition OFF, connect the DT-48493
jumper harnessto the X176 transmission 24-way connector at the transmission. Measure and record the resistance between the sensor signal and low reference terminals. Compare the actual sensor and circuit resistance to the expected sensor resistance. Refer to Temperature Versus Resistance .
- If the resistance is near the expected value, test the transmission internal harness signal circuit for a short to ground. If the circuit tests normal, replace the M15 drive motor generator.
- If the resistance is not near the expected value, test the transmission internal harness signal and low reference circuits for an open or shorted together condition. If the circuits test normal, replace the M15 drive motor generator.
NOTE:
The ignition must be ON to test the low reference circuit. Other DTCs will set with the X176 connector disconnected.
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.