Measure the voltage between body ground and display unit connector B (20P) terminal No. 1 and No. 2 individually. Is there battery voltage?
YES | - | Replace the display unit.■
NO | - | If the +B wire does not have voltage, repair open in the wire between the under-dash fuse/relay box and the navigation unit. If the ACC wire does not have voltage, repair open in the wire between the under-dash fuse/relay box and the navigation unit.■