16. IGNITION SYSTEM ATV 50 CDI UNIT CDI unit couple WIRE HARNESS INSPECTION MXU 50 REVERSE/ MXU 50 Measure the voltage between the black wire terminal and ground or between the black wire and green wire terminals. There should be battery voltage with the ignition switch "ON", and no voltage with the ignition switch "OFF" CDI Unit MX'ER 50 16-7