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Circuit/System Testing

IMPORTANT: Diagnose any antilock brake system (ABS) related DTCs before performing this diagnostic.
  1. Ignition OFF, disconnect the X2 harness connector at the radio.
  2. Ignition ON, operate the vehicle drive wheels at 5 mph. Test for 3-7 Hertz between the VSS circuit terminal E and ground.
    • If the reading is not as specified, test the VSS circuit for an open, high resistance, short to ground or short to voltage. If the circuit tests normal replace the ECM.
  3. If the circuit tests normal, replace the radio.
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