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HOMESERVICE MANUALSBUICK2019CASCADA BASEREPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEMDATA COMMUNICATION SYSTEMDIAGNOSTIC INFORMATION AND PROCEDURESDTC U1653CIRCUIT/SYSTEM TESTING
2019 Buick Cascada Base

Circuit/System Testing

2019 Buick Cascada BaseSECTION Circuit/System Testing
NOTE:

Use the schematic and the connector end view to identify the device's serial data communication enable circuit and chassis high speed GMLAN serial data circuit terminals.

  1. Ignition/Vehicle OFF, disconnect the harness connectors at the device setting this DTC, ignition ON/Vehicle In Service Mode.
  2. Verify a test lamp illuminates between the serial data communication enable circuit terminal and ground.
    • If the test lamp does not illuminate 
    1. Ignition/Vehicle OFF, remove the test lamp, disconnect the harness connectors at the K9 Body Control Module.
    2. Test for infinite resistance between the serial data communication enable circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in the serial data communication enable circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module.
    • Go to next step: If the test lamp illuminates 
  3. Test for less than 4.5 V between each chassis high speed GMLAN serial data circuit terminal and ground.
    • If 4.5 V or greater 

      Refer to DTC U0077  to test for a short to voltage.

    • Go to next step: If less than 4.5 V 
  4. Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down.
  5. Test for greater than 100 Ω between each chassis high speed GMLAN serial data circuit terminal and ground.
    • If 100 Ω or less 

      Refer to DTC U0077  to test for a short to ground.

    • Go to next step: If greater than 100 Ω 
  6. Test for less than 2 Ω in each of the chassis high speed GMLAN serial data circuits end to end between the harness connector at the device setting this DTC and the appropriate X84 Data Link Connector terminals listed below.
    • Chassis high speed GMLAN serial data circuit terminal 12
    • Chassis high speed GMLAN serial data circuit terminal 13
    • If 2 Ω or greater 

      Repair the open/high resistance in the serial data circuit.

    • Go to next step: If less than 2 Ω 
  7. Replace the device setting this DTC.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.