Freelander System Description and Operation
AUTOMATIC GEARBOX - JATCO
DESCRIPTION AND OPERATION
44-25
Fluid Temperature Sensor
The fluid temperature sensor is located within the gearbox on the valve block. The EAT ECU uses this sensor to
monitor the gearbox fluid temperature.
When the fluid is cold, the EAT ECU changes gear at higher engine speeds to promote faster fluid warm-up. If the
fluid temperature becomes too high, the EAT ECU transmits a cooling request on the CAN link to the ECM to operate
the cooling fans.
The fluid temperature sensor has an electrical output to pin 39 of the EAT ECU which also provides an earth path for
the sensor.
The fluid temperature sensor is a negative temperature coefficient sensor. As the temperature rises, the resistance
in the sensor decreases. As temperature decreases, the resistance in the sensor increases and the output voltage to
the EAT ECU changes in proportion.
The output voltage from the sensor is in the range of 0 - 2.5 Volts with the lower voltage representing the highest
temperature.
The change in resistance is proportional to the temperature of the gearbox fluid. From the resistance of the sensor,
the EAT ECU calculates the temperature of the gearbox fluid. Should the fluid temperature sensor fail the EAT ECU
uses the last recorded EAT ECU value as a default value.
Fluid Temperature Sensor Resistance Values
Temperature
°
C (
°
F)
Resistance k
Ω
-40 (-40)
54.90
-20 (-4)
16.70
0 (32)
6.02
20 (68)
2.50
40 (104)
1.16
60 (140)
0.59
80 (176)
0.33
100 (212)
0.19
120 (248)
0.12
140 (284)
0.08
