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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 476 (Antilock Brake System - Hybrid (Hp2)) >> Diagnostic Information and Procedures >> DTC C0294, C120C, or C12F8 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2012 GMC Yukon, 2012 Chevrolet Tahoe, and 2012 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the brake master cylinder piston position sensor.
  2. 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.
  3. 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.
  4. 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.
  5. Install a 3A 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.
  6. 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.
  7. 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.
  8. If all circuits test normal, replace the brake master cylinder piston position sensor. If DTC resets, replace the EBCM.
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