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Home >> Cadillac >> 2007 >> Escalade EXT >> Repair and Diagnosis >> External Pages >> Different car >> Section 1184 (Data Communication System) >> Diagnostic Information and Procedures >> DTC U1826 or U1827 >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.

Yaw Rate Sensor DTC U1826 

  1. Use the DTC Descriptor and Diagnostic Aids above, determine the module that is not communicating that should be tested.
  2. Ignition OFF, disconnect the harness connector at the Yaw Rate Sensor.
  3. Ignition ON, verify that a test lamp illuminates between the Yaw Rate Sensor voltage (12-volt ref) circuit terminal 1 and ground.
    • If the test lamp does not illuminate, test the circuit for a short to ground, or open/high resistance. If the circuit tests normal, replace the EBCM.
  4. Ignition OFF, test for less than 5 ohms between the Yaw Rate Sensor low reference circuit terminal 6 and ground.
    • If greater than the specified value, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the EBCM.
  5. Test for less than 1 ohm in the CAN bus serial data circuits between the Yaw Rate Sensor and the EBCM.
    • If greater than 1 ohm, test the serial data circuits terminals 2 and 3 for open/high resistance.
  6. If all circuits test normal, replace the yaw rate sensor.

Steering Wheel Position Sensor (Steering Angle Sensor) DTC U1827 

  1. Use the DTC Descriptor and Diagnostic Aids above, determine the module that is not communicating that should be tested.
  2. Ignition OFF, disconnect the harness connector at the Steering Wheel Position Sensor.
  3. Ignition ON, verify that a test lamp illuminates between the Steering Wheel Position Sensor voltage (12-volt ref) circuit terminal 2 and ground.
    • If the test lamp does not illuminate, test the circuit for a short to ground, or open/high resistance. If the circuit tests normal, replace the Steering Wheel Position Sensor.
  4. Ignition OFF, test for less than 5 ohms between the Steering Wheel Position Sensor low reference circuit terminal 1 and ground.
    • If greater than the specified value, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the Steering Wheel Position Sensor.
  5. Test for less than 1 ohm in the CAN bus serial data circuits between the Steering Wheel Position Sensor and the Yaw Rate Sensor.
    • If greater than 1 ohm, test the serial data circuits terminals 3 and 4 for open/high resistance.
  6. If all circuits test normal, replace the Steering Wheel Position Sensor.
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