2004 John Deer Buck Utility ATV 500, 500EX and 500EXT Service Manual, Page 142Get this manual
calculate the engine RPM and among other things, control the maximum engine RPM to compute and select the proper parameters accordinglyThe VSS (vehicle speed sensor) supplies the MPEM with the vehicle speedThe GBPS (gearbox position sensor) supplies the MPEM with the gear position (1, 2, 3, 4, 5)The STPS (sub-transmission position sensor) supplies the MPEM with the sub-transmission position (P, R, N, H, L)The brake light switch is also used by the MPEM to allow engine starting in other position than PARK and NEUTRALOther sensors are utilized but they are not related to the shifting system
The ignition coil receives its signal from the MPEMThe ignition coil steps up the input voltage for the IDI system and the end result is firing of the spark plugsIt is double coil that provides separate spark to each spark plugThe double control circuit in the MPEM works separately on each part of the ignition coil so, one ignition coil still could work while the other might be defective
An electronically controlled hydraulic shift system is utilizedIt is made up of the following components: