TD5 Defender
18
ENGINE MANAGEMENT SYSTEM
20
DESCRIPTION AND OPERATION
SENSOR - FUEL TEMPERATURE (FT)
The FT sensor is located at the RH rear of the engine in the connector block, with the tip of the sensor inserted at
least 10mm into the fuel flow. This allows the sensor to respond correctly to changes in fuel density in relation to
fuel temperature.
The FT sensor works as an NTC sensor. As fuel temperature rises the resistance in the sensor decreases. As
temperature decreases the resistance in the sensor increases. The ECM is able to compare the voltage signal to
stored values and compensates fuel delivery as necessary for hot engine start.
The operating range of the sensor is -40 to 130
°
C (-40 to 266
°
F).
Input / Output
The ECM (C0158-19) provides the FT sensor (C0184-2) with a 5 volt supply signal on a yellow/white wire. The
sensor is earthed (C0184-1) via the ECM (C0158-5) on a pink/black wire.
The FT sensor can fail or supply an incorrect signal if one or more of the following occurs:
•
Sensor open circuit.
•
Short circuit to vehicle supply.
•
Short circuit to vehicle earth.
•
Sensor fitted incorrectly.
In the event of an FT sensor signal failure any of the following symptoms may be observed:
•
Difficult cold start.
•
Difficult hot start.
•
Driveability concern.
In the event of a component failure, the ECM reverts to a fixed value of 60
°
C stored in its memory.
