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Home >> Chevrolet >> 2008 >> Aveo LT, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 122 (Antilock Brake System) >> Diagnostic Information and Procedures >> DTC C0121 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2011 Chevrolet Aveo. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the EBCM.
  2. Test for less than 5 Ω between the ground circuits listed below and ground:
    • Terminal 13
    • Terminal 26
    • If greater than the specified range, test for an open/high resistance in the ground circuit.
  3. Ignition ON, verify that a test lamp illuminates between the B+ circuits listed below and ground:
    • Terminal 1
    • Terminal 14
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, replace the brake pressure modulator valve and EBCM assembly.
  4. If all circuits test normal, replace the brake pressure modulator and EBCM assembly.