A VIA car, the user reflects the car navigation system marked on the direction of the vehicle movement and the actual direction of the vehicle opposite. According to the car's fault phenomenon, decided to first self-diagnosis of the navigation system. (Start has been described above), and read the vehicle position signal check mode REV signal results, the standard: the input signal is normal (ignition switch ON, shift lever R block when the 10 ~ 14V voltage, remove the navigation ECU Of the connector, the use of a multimeter to measure the voltage between REV and GND1, 10 ~ 14V normal.
     According to the requirements of the vehicle maintenance manual, then replace the navigation system ECU, troubleshooting.