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4.34
ELECTRONIC FUEL INJECTION
9923142 - 2011 RANGER RZR / RZR S / RZR 4 Service Manual
© Copyright 2010 Polaris Sales Inc.
ENGINE COOLANT TEMPERATURE
SENSOR (ECT)
Operation Overview
Mounted on the cylinder head, the engine temperature sensor
measures coolant temperature. The engine temperature sensor is
a Negative Temperature Coefficient (NTC) type sensor, as the
temperature increases the resistance decreases.
Coolant passes through the cylinder and by the sensor probe,
varying a resistance reading which is relayed to the ECU. This
signal is processed by the ECU and compared to its
programming for determining the fuel and ignition
requirements during operation. The ECU also uses this signal to
determine when to activate the fan during operation.
ECT Sensor Test
To quickly rule out other components and wiring related to the
ECT, disconnect the harness from the ECT sensor and start the
engine. After a few seconds, the fan should turn on and the
“Check Engine” indicator should display on the instrument
cluster. This indicates all other components are working
properly.
Refer to Chapter 10 for additional ECT sensor information.
Polaris dealers can test the sensor by using the Digital Wrench™
Diagnostic Software (dealer only).
ECT Sensor Replacement
1. Remove the driver and passenger seats.
2. Remove the rear service panel to access the ECT sensor.
3. Drain coolant to level below sensor.
4. Disconnect sensor from engine harness.
5. Using a wrench, remove and replace the sensor, applying
a light coating of thread sealant to aid installation.
6. Torque the sensor to 17 ft. lbs. (23 Nm).
7. Add the required amount of coolant and properly bleed the
cooling system (see Chapter 3).
ECT
ECT Sensor
ECT Sensor Resistance Readings
Temperature F (C) Resistance
68 F (20 C) 2.5 k ± 6%
86 F (30 C) 1.7 k ± 6%
104 F (40 C) 1.2 k ± 6%
122 F (50 C) 834 ± 6%
140 F (60 C) 596 ± 6%
158 F (70 C) 435 ± 6%
176 F (80 C) 323 ± 6%
194 F (90 C) 243 ± 6%
212 F (100 C) 186 ± 6%
= T
ECT Retaining Bolt Torque:
17 ft. lbs. (23 Nm)