LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Cadillac >> 2015 >> CTS V, Automatic Trans >> Repair and Diagnosis >> Engine Performance >> System >> Data Communication System (Coupe) >> Diagnostic Information and Procedures >> DTC U1826 or U1827: Lost Communication With Module >> Circuit/System Testing
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Circuit/System Testing

DTC U1826

  1. Ignition OFF, disconnect the harness connector at the Yaw and Lateral Accelerometer 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 circuit tests normal, replace the EBCM.
  4. Ignition OFF, disconnect the harness connector at the EBCM and the Steering Wheel Position Sensor.
  5. Ignition ON, test for less than 1 V between each serial data circuit terminal listed below and ground.
    • EBCM serial data circuit terminal 33
    • EBCM serial data circuit terminal 21
    • If greater than the specified range, test the appropriate serial data circuit for a short to voltage.
  6. Ignition OFF, test for infinite resistance between each serial data circuit terminal listed below and ground.
    • EBCM serial data circuit terminal 33
    • EBCM serial data circuit terminal 21
    • If less than the specified range, test the appropriate serial data circuit for a short to ground.
  7. Test for less than 2 Ω in each serial data circuit between the Yaw and Lateral Accelerometer Sensor and the EBCM.
    • Yaw and Lateral Accelerometer Sensor serial data circuit terminal 3 and EBCM serial data circuit terminal 33
    • Yaw and Lateral Accelerometer Sensor serial data circuit terminal 1 and EBCM serial data circuit terminal 21
    • If greater than the specified range, test the appropriate serial data circuit for an open/high resistance.
  8. Test for infinite resistance between the EBCM serial data circuit terminal 33 and the EBCM serial data circuit terminal 21.
    • If less than the specified range, test the serial data circuits for a short together.
  9. If all circuits test normal, replace the Yaw and Lateral Accelerometer Sensor.

DTC U1827

  1. Ignition OFF, disconnect the harness connector at the Steering Wheel Position 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 circuit tests normal, replace the EBCM.
  4. Ignition OFF, disconnect the harness connector at the EBCM and the Yaw and Lateral Accelerometer Sensor.
  5. Ignition ON, test for less than 1 V between each serial data circuit terminal listed below and ground.
    • EBCM serial data circuit terminal 33
    • EBCM serial data circuit terminal 21
    • If greater than the specified range, test the appropriate serial data circuit for a short to voltage.
  6. Ignition OFF, test for infinite resistance between each serial data circuit terminal listed below and ground.
    • EBCM serial data circuit terminal 33
    • EBCM serial data circuit terminal 21
    • If less than the specified range, test the appropriate serial data circuit for a short to ground.
  7. Test for less than 2 Ω in each serial data circuit between the Steering Wheel Position Sensor and the EBCM.
    • Steering Wheel Position Sensor serial data circuit terminal 3 and EBCM serial data circuit terminal 33
    • Steering Wheel Position Sensor serial data circuit terminal 1 and EBCM serial data circuit terminal 21
    • If greater than the specified range, test the appropriate serial data circuit for an open/high resistance.
  8. Test for infinite resistance between the EBCM serial data circuit terminal 33 and the EBCM serial data circuit terminal 21.
    • If less than the specified range, test the serial data circuits for a short together.
  9. If all circuits test normal, replace the Steering Wheel Position Sensor.
scientia non olet · About LEMON Manuals