Operating instructions

Type II System - 1991 To Current EFls
Type II EFI systems incorporate an engine coolant
temperature sensor. This sensor is positioned
in the
engine water jacket where it is
able to receive and relay
reliable engine top end temperature to the ECU. This
sensor
also controls the temperature light and a fail safe
mode. The
"TEMP" dash light will come on and begin to
blink
slowly when the coolant reaches an unsafe
temperature.
If the temperature continues to increase, the
light
will begin to blink faster; at this time the EFI system
will increase the fuel being supplied to the engine.
ENGINE ELECTRICAL
EFI Electronics
This increase in fuel will be noticed by a decrease in engine performance which is designed to protect the engine in
an overheat condition. The increased
fuel will continue until the engine coolant reaches a safe temperature and
the
light goes out. Correcting this problem may be as simple as driving the machine slower and/or driving in a snow
condition which
allows for more snow to be thrown onto the heat exchangers. If this condition continues, check the
cooling system, coolant
level, water pump belt tension, etc.
To check sensor function, connect a select monitor and advance to mode F22. With engine cold, observe reading.
It should be near the readings of the ATS and CTS in degrees centigrade. Start engine and observe temperature
increase as engine warms up.
If readings vary greatly or fluctuate from other sensor readings, check harness and
connectors for condition and repair as necessary.
If no other problems can be found, and incorrect readings
continue, replace sensor.
Select Monitor Readings
Mode Description Normal Reading
F22
Water Temp Co
Cold En gi ne Room Temp
Bench testing of a temperature sensor can be accomplished by measuring resistance between sensor wire
terminal and sensor
shell; then comparing reading to graph shown. An easier and more accurate method is to use
the select monitor to indicate what temperature reading the ECU receives from the sensor.
If the engine has not
recently run, the sensor should read at or near room temperature. A
radically different readi ng from room
temperature could indicate a problem with sensor, wire to sensor, any
of sensor connections, battery, or ECU.
Verify and repair any problem before attempting to operate machine.
The sensor's resistance curve is
shown at right. Resistance of the
sensor
is high when it is cold, and
lowers as its temperature increases.
This creates
low current flow through
the sensor at
low temperatures and
high current
flow as the temperature
increases.
NOTE: The formula for
converting
OF to °C is (0 F = °C x 1.8
+ 32) ;."
80
40
20
10
6
4
2
1
0.6
0.4
0.2
Resistance (kQ)
-20
o
4.59
2.5kQ /20° C
20 40 60
80 1 00 1 20
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