85 engine electrical.pdf - Vintage Snow

cSelect MonitorThe select monitor (PN 2870969) is designed toprovide easy, accurate diagnostic and serviceinformation to the technician. When installed on themachine it will provide both dynamic and staticdisplays of the function of critical fuel system controlcomponents. It also has the ability to display thecontents of the ECU memory. With this tool, electricalservice of the EFI system should be quick and easy.Remove protective plug from diagnostic plug inmachine harness next to ECU. Connect selectmonitor to instrument harness, to service harness,and to diagnostic plug in. Install program cartridgeinto select monitor. Turn on ignition switch and placehandlebar kill switch into run position. Turn on selectmonitor switch. On most models the monitor displaywill now light up.NOTE: On 1993 500 models, it is necessary toconnect the Red/Yellow and Yellow/Green wire in the5 pin electric start coupler with a jumper wire tomaintain power to the ECU and select monitor. Type Imodels will stay powered up with switches on. OnType II systems, the time will be limited unless theengine is running. On 1994 and later models, the ECUwill remain powered for approximately one minute atroom temperature and above.There are two ways to search for information with themonitor. You can scroll through the different modes inorder until the correct information is found, or you canselect the specific mode letter and number andadvance to the specific information that you want.Electronic Control UnitThe Electronic Control Unit (ECU) is the brain of theEFI system. It is a digital computer which holds thememory chip for the read out of basic injector openingduration on a three dimensional map. There are twoECU systems used, Type 1 for the RXL and Type 2 forthe 500 EFI snowmobiles. Each system receives thesame type of information from the sensors. The ECUincorporates a number of special features. Some ofthese features are: adjustable low speed mixturecontrol, automatic cold engine start up enrichment,engine over temperature protection, flooded enginecleanout mode, failsafe feature and LED selfdiagnostic system. In the event that any sensorshould give inaccurate or no information, the ECU willthen flash a coded light sequence to identify theaffected sensor. NOTE: It is important to note that theECU will not identify mechanical problems. Onlysensor inputs are monitored. For example, low fuelpressure or lack of fuel will not be diagnosed.The ECU can only tell if a sensor reading is within aspecific range. For example, a failure code will not beindicated if throttle position shows 3.9 0when thethrottle is actually wide open. Use display of throttlepOSition to ensure the readings reflect actualconditions. This same concept applies to thetemperature sensors and the barometric sensor.4.51ENGINE ELECTRICALSystem III - Electronics TestingECU Part NumbersSERVICE HARNESS 'Type I w/o chipType I w/o chip Elect. StartType II w/o Chip241002824100292410030"8/94.. .~ ....