Electronic Control Unit (Ecu) - Polaris Ranger RZR XP 900 2011 Service Manual

ELECTRONIC CONTROL UNIT (ECU)
Operation Overview
The ECU is the brain or central processing computer of the
entire EFI fuel/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 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
the 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" and
"Diagnostic Trouble Code Table" or by using Digital Wrench
TM.
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 is exceeded, the ECU suppresses the injection
signals, cutting offthe fuel flow and retards the ignition timing.
This process repeats it self in rapid succession, limiting
operation to the preset maximum.
ELECTRONIC FUEL INJECTION
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 RZR XP 900 ofthe same model may
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be used without system or engine component damage.
ECU Replacement
Although the need for ECU replacement is unlikely, a specific
replacement procedure is required to ensure that all essential
data contained within the original ECU is transferred to the
replacement ECU.
IMPORTANT: Refer to this procedure and carefully
follow all instructions provided in Digital Wrench™.
1. Carefully follow the ECU replacement instructions
provided in Digital Wrench™ to ensure that all essential
data contained within the original ECU is transferred to the
replacement ECU.
2. Remove the black plastic cover by lifting up on the tab.
Remove the retaining screw that attaches the ECU to the left
rear fender well.
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9923144 - 2011 RANGER RZR XP 900 Service Manual
© Copyright 2011 Polaris Sales Inc.