85 engine electrical.pdf - Vintage Snow

!£WitECU DiagnosticsENGINE ELECTRICALEFI ElectronicsIf any of the main sensors should malfunction while the machine is being driven, the ECU will sense a problem andproceed to an over-rich "fail-safe" mode. An open or shorted circuit in any of the sensor circuits will show the ECUa reading outside of what it normally sees and the ECU will determine that a problem exists. Without this feature,certain kinds of failures could cause the mixture to be leaner than the required ratio and cause engine damage.This feature is important for engine protection. Once the sensor problem is determined and corrected, the ECUwill return to the original map.If any of the injectors or sensors should malfunction during operation, the ECU will record this information and startflashing a Light Emitting Diode (LED) code informing the mechanic/owner which component failed. The LED is onthe right of the ECU, in front of the main plug. See ECU photo. If the problem still exists and is ongoing, the LEDwill continuously flash the code. If the problem occurred but the machine is now operating properly (intermittent), itwill be stored in the memory and can be drawn out of the ECU by connecting the gray and black wires together atthe diagnostic plug. The LED will then begin blinking long followed by short light pulses; then a pause and the longand short pulses again. The long pulses are the first digit in the code and the short pulses are the second digit.Compare the code to the following trouble code chart to determine the problem. Remember that the problem canexist in the sensor, the power feed to the sensor, the sensor ground, connectors, or the part of the injector orsensor circuit inside the ECU.Select Monitor ReadingsMode FBa is for existing problem diagnosis. Pressbuttons F, B, a and enter. If there is an existingproblem, a code number and the abbreviation of theproblem component will appear. See the chart for anexplanation of the code numbers. The LED will alsodisplay this code. Example: Code 12- the light willdisplay one long and two short pulses.Mode FB 1 is for retrieving trouble codes from the ECUmemory. If a problem happened sometime during themachine's operation, but everything is operatingproperly at the present time, the ECU memory willverify which component was at fault. This is good forfinding intermittent problems such as a wiring open orshort. Press the F, B, 1 and enter buttons. If thedisplay shows one of the above codes, check thatcomponent and its circuit. If nothing appears, there isnothing in memory. NOTE: If the ECU power isdisconnected at any time, this memory will be erased.Mode FCa is used for erasing problem codes whichare stored in the ECU's memory. To erase theproblem codes, certain steps must be followed inorder. First select the mode for the component whichindicated a failu re. Next, press F, C, a and enter on themonitor. The display will ask "Memory clear? a-yesand 1-no". By pressing a and enter the memory will beerased. Indication of the memory being cleared will bea display of "Please key off'.Monitorand LEDCode111213141415212223313233SystemType Type Abb. ComponentOne TwoX X THV Throttle PositionSensorX X TCaseCrankcaseTemperature SensorX X T Air Intake AirTemperature SensorX ALT Barometric PressureSensorX TW Water TemperatureSensorX ALT Barometric PressureSensorX X Inj 1 Mag Side InjectorX X Inj 2 Center Injector orPTa on TwinsX Inj 3 PTa InjectorX VB Low Battery VoltageX VB Low ChargingSystem OutputX COl COl OutputoMode DescriptionNormal ReadingFBD Existing Trouble Faults Presently ExistingCodesFB1 Memory Trouble Faults Which AreCodesIntermittentFCD Memory Clear Used to Remove StoredInformation4.618/94