Circuit/System Testing

2008 Chevrolet Chevy Express G3500, Van Passenger ExtendedSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2012 GMC Yukon, 2012 Chevrolet Tahoe, and 2012 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the transmission X176 24-way harness connector.
  2. NOTE:

    The ignition must be ON to test the low reference circuit. Other DTCs will set with the X176 connector disconnected.

  3. Connect DT-48493Β  jumper harness.
  4. 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.
  5. 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.
  6. 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
      NOTE:

      If a short to voltage is found, test the motor temperature sensor for damage.

    • 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.
  7. Ignition OFF, connect the DT-48493Β  jumper harness to 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 ResistanceΒ .
    • 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.
RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

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.