Electronic Control Unit (Ecu); Ecu Operation Overview; Ecu Service; Ecu Replacement - Polaris RZR PRO R Service Manual

ENGINE ELECTRICAL

ELECTRONIC CONTROL UNIT (ECU)

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), barometric pressure, intake air temperature, boost
pressure, 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
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®. 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 off the fuel flow and retards
the ignition timing. This process repeats it self in rapid
succession, limiting operation to the preset maximum.
RPM Limit:

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 RZR of the same model may be
used without system or engine component damage.
4.2
8800

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.
NOTICE
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 seats. On 4-seat models, remove rear seats.
3. Remove five push-pins
remove close-off panel.
4. Remove the plastic cover
tab.
9940259 R02 - 2022 RZR PRO R / PRO R 4 Service Manual
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and one fastener and
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by pulling on the outer
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