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Home >> GMC >> 2014 >> Terrain Denali, 4D Utility >> Repair and Diagnosis >> Engine Performance >> System >> Data Communication System >> Diagnostic Information and Procedures >> DTC U1826 or U1827: Lost Communication with Sensor Module on Powertrain Expansion CAN Bus >> Circuit/System Testing

Circuit/System Testing

NOTE:

Terminal and connector identifiers will be different depending on the individual device being tested. Use Schematic Reference and Connector End View Reference to identify device's connector, B+, ignition, ground, and serial data circuit terminals.

  1. Ignition OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 meters (9.8 feet) away from vehicle. Disconnect all harness connectors at the device that is not communicating. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuit terminal 6 and ground.
    • If 10 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 10 Ω 
  3. Ignition ON.
  4. Verify a test lamp illuminates between the ignition circuit terminal 5 and ground.
    • If the test lamp does not illuminate 
    1. Ignition OFF, remove the test lamp, disconnect the harness connectors at the K17 Electronic Brake Control Module.
    2. Test for infinite resistance between the ignition circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the ignition circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K17 Electronic Brake Control Module.
    • If the test lamp illuminates 
  5. Ignition OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 meters (9.8 feet) away from vehicle. Disconnect the harness connectors at the device setting the DTC. It may take up to 2 minutes for all vehicle systems to power down.
  6. Test for less than 2 Ω in each of the serial data circuits end to end between the non-communicating device and the device setting the DTC.
    • If 2 Ω or greater 

      Repair the open/high resistance in the serial data circuit between the non communicating device and the device setting the DTC or a serial data splice pack.

    • If less than 2 Ω 
  7. Replace the device that is not communicating.
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