The signal is bad or there is interference.-----------Move from those areas.

The antenna of radio is not installed well.-----------Re-plug the radio antenna.

The hardware of circuit is defective.-----------For this issue, it needs the professional person to check the circuit.

The navigation path is wrong. -----------Reset up the path (Menu-Options-System-Navigator Path).

The files of map are damaged.-----------Re-copy the map files.

The SD card is defective.-----------Replace another SD card with map.

The matching goes wrong.-----------Rematch.

The microphone is defective.-----------Replace the microphone.

The software is missing.-----------Update the device. 

The format of the files is not supported.-----------Replace with the supported one.

The software is missing.-----------Update the device.

There is no 12 voltage of the Reverse cable.-----------Reconnect the "Reverse"cable and measure the voltage. 

The camera is defective.-----------Replace the camera.

The SD card is defective-----------Replace the SD card.

The SD slot is defective-----------Let professional person replace the SD card slot.

The cable connected with SD card is loosen.-----------For this issue, let professional person to re-fasten.

The hardware circuit is defective.-----------For this issue, let professional person to check the circuit.

There is dust on the laser head or the laser head is defective.-----------Clean the laser head or replace it.

Please check the disk is defective or not.-----------Change another disk and check. 

The hardware circuit is defective.-----------For this issue, let professional person to check the circuit.

There are something on the face of touch screen or the protective film is sticking so fasten---------Please tear off the protective film, remove the foreign substance, then enter the calibration interface to calibrate.

The touch screen is defective.-----------Replace the touch screen.

The hardware circuit is defective.-----------For this issue, let professional person to check the circuit.

The setting of OSD is not adjusted well.-----------You can adjust the OSD setting to appropriate options.

There is no 3.3V output from the GPS plug.-----------Replace the GPS module.