Electronic Control Unit; Operation Overview - Polaris Sportsman 850 Service Manual

ELECTRONIC CONTROL UNIT

OPERATION OVERVIEW

The ECU is a solid state component that serves as the
controller for the fuel injection system.
The ECU receives input from the EFI sensors including,
but not limited to:
• Engine Coolant Temperature
• Intake Temperature/Manifold Absolute Pressure (T-
MAP)
• Oxygen Sensor
• Throttle Position Sensor
The inputs cause the ECU to respond based on it's
software calibration. The ECU responds by opening and
closing the output circuits of the EFI system. These
include but are not necessarily limited to:
• Fuel Injectors
• Electronic Throttle Control (ETC)
• Oxygen Sensor Heater
• Ignition Coil
• Idle Air Controller (IAC)
During operation, the ECU
diagnostic checks of itself, each of the sensors, and
system performance. If a fault is detected, the ECU turns
on the "Check Engine" light in the speedometer and
stores the fault code in its fault memory. Depending on
the significance or severity of the fault, normal operation
may continue, or "Fail-Safe" operation (slowed speed,
richer running) may be initiated. A technician can
determine the cause of the "Check Engine" light by
referencing the "Instrument Cluster Trouble Code
Display" and "Diagnostic Trouble Code Table" or by using
Digital Wrench®. The ECU requires a minimum of 7.0
volts to operate. The memory in the ECU is operational
the moment the battery cables are connected.
To prevent engine over-speed and possible failure, an
RPM-limiting feature is programmed into the ECU. If the
maximum RPM limit (7600) is exceeded, the ECU
suppresses the injection signals, cutting off the fuel flow.
This process repeats it self in rapid succession, limiting
operation to the preset maximum.
continually performs
FUEL SYSTEM
Maximum RPM Limit: 7600
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