Disconnect the scanner cable at both ends. At the scanner junction box, short the sync pair together. Back at the display, measure continuity with a multimeter (should be <1 ohm). Then test insulation resistance (should be >10 megaohms to ground). High resistance but good continuity? You have water wicking inside the cable – replace it.

Confirm the scanner is physically rotating. If it is stationary, the system cannot generate sync signals. This could be due to a failed motor or relay. Signal Testing (Service Technician Required): Measure the voltage of the Trigger (TRIG) Azimuth (AZI) signals at the terminal board.

Heat the scanner unit gently with a hot air gun (hair dryer). If the sync signal appears after heating, you have a on the encoder amplifier board. Conversely, if the error appears after heating, a component is thermally failing.

: In some cases, a system reset or reseating the radar interface cards can restore communication.

Prevention is cheaper than repair. Implement this quarterly checklist:

This article is for informational purposes. Always refer to the official JRC service manual for your specific radar model (JMA-6100/7100/9100/9170/NXT/NX series) before performing repairs.