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Home >> Chevrolet >> 2019 >> Express 2500 Base, Van Cargo Extended, 2.8L Eng VIN 1 >> Repair and Diagnosis >> Engine Performance >> System >> Data Communications System >> Diagnostic Information and Procedures >> DTC U0126 >> Circuit/System Testing
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Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the B99 Steering Wheel Angle Sensor.
  2. Test for less than 10 Ω between the ground circuit terminal 6 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 5 and ground.
    • If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the B99 Steering Wheel Angle Sensor.
  4. NOTE:

    The following test step is only applicable to low speed GMLAN modules.

  5. Test for less than 4.5 V between each of the serial data circuit terminals listed below and ground.
    • Terminal 1
    • Terminal 2
    • Terminal 3
    • Terminal 4
    • If greater than the specified range, refer to DTC U0077  to test for a short to voltage in the serial data circuit.
  6. Ignition OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m away from vehicle. It may take up to 10 min for all vehicle systems to power down.
  7. Disconnect the harness connector at the K17 Electronic Brake Control Module.
  8. Test for less than 2 Ω in each of the serial data circuits end to end:
    • B99 Steering Wheel Angle Sensor terminal 3 and K17 Electronic Brake Control Module terminal 5
    • B99 Steering Wheel Angle Sensor terminal 1 and K17 Electronic Brake Control Module terminal 6
    • If greater than the specified range, test the serial data circuit for an open/high resistance between the B99 Steering Wheel Angle Sensor and the K17 Electronic Brake Control Module.
  9. If all circuits test normal, replace the B99 Steering Wheel Angle Sensor.