1999-2004 Honda TRX400EX FourTrax Service Manual, Page 245Get this manual
ELECTRIC STARTER STARTER RELAY VOLTAGE
Disconnect the yellowlred wire connector of the starter relay switchMeasure the voltage between the wire harness side connector terminal (+) and ground (-)lellowAed !+)
If the battery voltage appears only when the starter switch is pushed with the ignition switch ON, the circuit normal
OPERATION CHECK
Disconnect the starter relay switch connectors and cablesConnect the fully charged 12 battery positive terminal to the relay switch yellowred wire connector terminal and negative terminal to the yellowlgreen wire connector terminalThere should be continuity between the large terminals while the battery is connected, and no continuity when the battery is disconnected