Circuit/System Testing
- Ignition OFF, disconnect the X4 harness connector at the radio.
- Ignition ON, operate the vehicle drive wheels at 5 mph. Test for 3-7 Hertz between the VSS circuit terminal 15 and ground.
- If not within the specified range, test the VSS circuit for an open, high resistance, short to ground or short to voltage. If the circuit tests normal replace the ECM.
- If the circuit tests normal, replace the radio.