Electronic Control Unit (Ecu); Operation Overview; Ecu Service - Polaris RANGER XP 900 2018-2019 Service Manual

ELECTRONIC CONTROL UNIT (ECU)

OPERATION OVERVIEW

The ECU is the brain or central processing computer of
the entire EFI fuel and ignition management system.
During operation, sensors continuously gather data
which is relayed through the wiring harness to input
circuits within the ECU. Signals to the ECU include:
ignition power (on/off), intake air temperature, manifold
absolute pressure (load), engine coolant temperature,
crankshaft position and engine speed (RPM), throttle
pedal position and battery voltage. The ECU compares
the input signals to the programmed maps in its memory
and determines the appropriate fuel and ignition
requirements for the immediate operating conditions.
The ECU then sends output signals to set injector
duration and ignition timing.
During operation, the ECU continually performs a
diagnostic check of itself, each of the sensors, and
system performance. If a fault is detected, the ECU turns
on the "Check Engine" light on the instrument cluster 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"page 4.35 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,
maximum engine RPM is controlled by the interface
between the ECU and Electronic Throttle Control (ETC).
Engine Max Operating RPM: 7250
9929399 R01 - 2018-2019 RANGER XP/ CREW 900/1000 Service Manual
© Copyright Polaris Industries Inc.

ECU SERVICE

Never attempt to disassemble the ECU. It is sealed to
prevent damage to internal components. Warranty is void
if the case is opened or tampered with in any way.
All operating and control functions within the ECU are
pre-set. No internal servicing or readjustment may be
performed. If a problem is encountered, and you
determine the ECU to be faulty, contact the Polaris
Service Department for specific handling instructions. Do
not replace the ECU without factory authorization.
For the purpose of troubleshooting, a known-good ECU
from another Polaris RANGER Fullsize XP 900 of the
same model may be used without system or engine
component damage.
FUEL SYSTEM
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4.21