1985-1987 Honda TRX 250 Fourtrax 250 Service Manual, Page 223Get this manual
LIGHTSSWITCHES OIL TEMPERATURE WARNING INDICATOR DOES NOT COME ON
Disconnect the 4P coupler from the control unit and check the continuity between Green wire terminal and ground
NO CONTINUITY Open circuit in Green wire
Short the BrownRed and Green wire terminals of the 4P couplerThe indicator should come on when the ignition switch is turned onINDICtrOA COMES ON