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Home >> Cadillac >> 2013 >> Escalade Base, AWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 4 (Antilock Brake System - Hybrid) >> Diagnostic Information and Procedures >> DTC C0277, C120C, C129A, C129B, C129D, C129E, C12B1, or C12F8 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. Perform a hydraulic check, refer to Brake Hydraulic and Assist System Diagnosis (Two-mode Hybrid) .
  2. Ignition OFF, disconnect the harness connector at the brake master cylinder piston position sensor.
  3. Ignition OFF, test for less than 5 Ω between the low reference circuit terminal 4 and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the EBCM.
  4. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 2 and ground.
    • If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM.
    • If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the EBCM.
  5. Verify the scan tool BMC Primary Piston Position Sensor A parameter is less than 1 V.
    • If greater than the specified range, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the EBCM.
  6. Install a 3 A fused jumper wire between the signal circuit terminal 3 and the 5 V reference circuit terminal 2. Verify the scan tool BMC Primary Piston Position Sensor A parameter is greater than 4.5 V.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM.
  7. Verify the scan tool BMC Primary Piston Position Sensor B parameter is less than 1 V.
    • If greater than the specified range, test the signal circuit terminal 1 for a short to voltage. If the circuit tests normal, replace the EBCM.
  8. Install a 3A fused jumper wire between the signal circuit terminal 1 and the 5 V reference circuit terminal 2. Verify the scan tool BMC Primary Piston Position Sensor B parameter is greater than 4.5 V.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM.
  9. If all circuits test normal, replace the brake master cylinder piston position sensor.
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