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Home >> Cadillac >> 2021 >> CT4 Sport, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 268 (Disc Brakes) >> Diagnostic Information and Procedures >> DTC C004A >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2022 Cadillac CT5. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF and all vehicle systems OFF, disconnect the connector at the B172LF Front Disc Brake Pad Wear Sensor-Left, the B172LR Rear Disc Brake Pad Wear Sensor-Left, the B172RR Rear Disc Brake Pad Wear Sensor-Right, and the B172RF Front Disc Brake Pad Wear Sensor-Right
  2. Test for less than infinite resistance between terminal 1 and 2 at each brake pad wear sensor.
    • If infinite resistance 
    1. Replace the appropriate brake pad wear sensor.
    • Go to next step: If infinite resistance 
  3. Ignition - On/Vehicle - In Service Mode. Verify a test lamp illuminates between ground circuit terminal 2 and B+ at the B172RF Front Disc Brake Pad Wear Sensor-Right.
    • If the test lamp does not illuminate 
    1. Repair the open/high resistance on the ground circuit or ground connection.
    • Go to next step: If the test lamp illuminates 
    1. Test for infinite resistance between the following circuits and ground.
      • Circuit 1611
      • Circuit 1613
      • Circuit 1612
      • Circuit 1610
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    2. Test the following circuits for an open/high resistance
      • Circuit 1611
      • Circuit 1613
      • Circuit 1612
      • Circuit 1610
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open/high resistance is not found
    1. Test the following circuits for a short to voltage.
      • Circuit 1611
      • Circuit 1613
      • Circuit 1612
      • Circuit 1610
      • If a short to voltage is found, repair the fault on the circuit.
      • Go to next step: If a short to voltage is not found
    2. Replace the K160 Brake System Control Module.
  4. All OK.


  1. Ignition OFF and all vehicle systems OFF, disconnect the connector at the B172LF Front Disc Brake Pad Wear Sensor-Left and the B172LR Rear Disc Brake Pad Wear Sensor-Left.
  2. Test for less than infinite resistance between terminal 1 and 2 at each brake pad wear sensor.
    • If infinite resistance 
    1. Replace the appropriate brake pad wear sensors.
    • Go to next step: If infinite resistance 
  3. Ignition - On/Vehicle - In Service Mode. Verify a test lamp illuminates between ground circuit terminal 2 and B+ at the B172LR Rear Disc Brake Pad Wear Sensor-Left.
    • If the test lamp does not illuminate 
    1. Repair the open/high resistance on the ground circuit or ground connection.
    • Go to next step: If the test lamp illuminates 
    1. Test for infinite resistance between the following circuits and ground.
      • Circuit 1611
      • Circuit 1613
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    2. Test the following circuits for an open/high resistance
      • Circuit 1611
      • Circuit 1613
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open/high resistance is not found
    1. Test the following circuits for a short to voltage.
      • Circuit 1611
      • Circuit 1613
      • If a short to voltage is found, repair the fault on the circuit.
      • Go to next step: If a short to voltage is not found
    2. Replace the K160 Brake System Control Module.
  4. All OK.
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