Ecu Replacement; Ecu Service - Polaris A12MH46AX Service Manual

To prevent engine over-speed and possible failure, an
RPM-limiting feature is programmed into the ECU. If the
maximum RPM limit (7000) is exceeded, the ECU will
suppress the ignition signal or injection signal. This
process repeats itself in rapid succession, limiting
operation to the preset maximum.
Sportsman 500 EFI RPM Limit:
This EFI system utilizes 2 methods -
"Hard" Limit - Ignition suppression occurs when RPM
peaks rapidly:
• High: 7000 RPM
• Returns: 6900 RPM
"Soft" Limit - Injector suppression occurs when RPM
reaches peak gradually:
• High: 7000 RPM
• Returns: 6900 RPM
RPM limits may vary slightly under operating conditions.

ECU Replacement

1. Remove the 2 retaining screws holding the ECU.
NOTE: Retain upper-left spacer located behind the
ECU for re-installation.
2. With the ignition turned off, disconnect the wire
harness by pulling the black slider away from the
ECU. Once the slider is fully extended, pull the
connector from the ECU, using great care not to
damage the harness
mechanism. NOTE: Should the black slider become
broken, replacement parts are available.
3. To install, reverse the procedures, DO NOT apply
dielectric grease to the connector, as it is a sealed
connector. Install the upper-left retaining screw
spacer and screws. Tighten screws to 10 in. lbs. (1.1
Nm).
connector or locking
9923412 - 2012 Sportsman 400/500 and EFI Tractor Service Manual
© Copyright 2011 Polaris Sales Inc.
500 EFI FUEL SYSTEM

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.
The relationship between the ECU and the throttle position
sensor (TPS) is very critical to proper system operation. If
the TPS is faulty, or the mounting position of the TPS is
altered, the TPS must be re-initialized.
For the purpose of troubleshooting, a known-good ECU
from a same-model Polaris 500 ATV EFI may be used
without system or engine component damage.
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