2004-2009 Honda TRX450R/TRX450ER Service Manual, Page 460Get this manual
BATTERYCHARGING SYSTEM (After '05)
REGULATORRECTIFIER
WIRE HARNESS INSPECTION
Disconnect the regulatorrectifier 5P black connectorCheck the connector for loose contacts or corroded terminalsBATTERY LINE (TRX450ER) Measure the voltage between the Red wire terminal and groundThere should be battery voltage at all timesIGNITION SWITCH LINE (TRX450R) Check the Red wire for continuity between the regulatorrectifier and ignition switch connectorsThere should be continuityCHARGING COIL LINE (TRX450ERR) Measure the resistance between the Yellow wire terminalSTANDARD: 0.11.0 (at 20C68F) Check for continuity between each Yellow wire terminal and groundThere should be no continuityREGULATOR RECTIFIER