Page 248 - Manual_Polaris_RZR_ProXP-20-21

ENGINE ELECTRICAL

ELECTRONIC CONTROL UNIT (ECU)

ECU OPERATION OVERVIEW ECU SERVICE
The ECU q is the brain or central processing computer Never attempt to disassemble the ECU. It is sealed to
of the entire EFI fuel/ignition management system. prevent damage to internal components. Warranty is void
During operation, sensors continuously gather data if the case is opened or tampered with in any way.
which is relayed through the wiring harness to input
circuits within the ECU. Signals to the ECU include: All operating and control functions within the ECU are
ignition power (on/off), barometric pressure, intake air pre-set. No internal servicing or readjustment may be
temperature, boost pressure, manifold absolute pressure performed. If a problem is encountered, and you
(load), engine coolant temperature, crankshaft position determine the ECU to be faulty, contact the Polaris
and engine speed (RPM), throttle position and battery Service Department for specific handling instructions. Do
voltage. The ECU compares the input signals to the not replace the ECU without factory authorization.
programmed maps in its memory and determines the For the purpose of troubleshooting, a known-good ECU
appropriate fuel and ignition requirements for the from another Polaris RZR of the same model may be
immediate operating conditions. The ECU then sends used without system or engine component damage.
output signals to set injector duration and ignition timing.

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.
During operation, the ECU continually performs a
diagnostic check of itself, each of the sensors, and 2. Remove the plastic cover q by pulling on the upper
system performance. If a fault is detected, the ECU turns tab.
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:
8800

4.2 9930583 R01 - 2020-2021 RZR PRO XP / XP 4 Service Manual
© Copyright Polaris Industries Inc.