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Home >> Cadillac >> 2018 >> CT6 Plug-In >> Repair and Diagnosis >> Brakes >> Parking Brake System >> Diagnostic Information and Procedures >> DTC C1138 >> Circuit/System Testing

Circuit/System Testing

NOTE:
  • You must perform the Circuit/System Verification before Circuit/System Testing.
  • Some control module ground circuits may require up to 20 min after the ignition is turned off before achieving a resistance reading of less than 5 Ω. In most cases the readings will drop below 20 Ω within 1 min indicating the control module is going to sleep.

DTC C1138 03 or DTC C1138 07 

  1. Ignition OFF and all vehicle systems OFF, disconnect the X1 harness connector at the K17 Electronic Brake Control Module. It may take up to 2 min for all vehicle systems to power down.
  2. Test for less than 10 Ω between ground circuit terminal 46 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.
    • Go to next step: If less than 10 Ω 
  3. Verify a test lamp illuminates between B+ circuit terminal 1 and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the B+ circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF.
    2. Test for infinite resistance between the B+ circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K17 Electronic Brake Control Module.
    • Go to next step: If the test lamp illuminates 
  4. Replace the K17 Electronic Brake Control Module.

DTC C1138 58 

  1. Verify that no other DTCs are set.
    • Go to next step: If no other DTCs are set 
  2. Using the S91 Park Brake Control Switch, apply and release the park brake.
  3. Verify that the DTC does not reset.
    • If the DTC resets 

      Replace the K17 Electronic Brake Control Module.

    • Go to next step: If the DTC does not reset 
  4. All OK.
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