Fuel Temperature Sensor, Short To Low Source - New Holland CX720 Repair Manual

0401.4-FUEL TEMPERATURE SENSOR, SHORT TO LOW SOURCE

(SERVICE TOOL FAULT CODE XXX) (B.20.A.95.89 - G.30.B.53)
CX860, CX880
0401.4 - FUEL TEMPERATURE SENSOR, SHORT TO LOW SOURCE (SERVICE TOOL FAULT CODE XXX)
Context:
Engine enabled - no restriction on fuel or speed
Cause:
No signal or signal range outside threshold limits
Signal not plausible or intermittent fault
Possible failure modes:
1. Faulty fuel temperature sensor (B40)
2. Faulty connector or wiring
Solution:
1. Check connector at sensor.
A. Ensure the connector X212 is not damaged, the terminals are in the correct position in the housing, and
that the fit is tight on the sensor. Repair or replace damaged components as required.
B. If the connector is okay continue with step 2.
2. Check sensor.
A. To test the sensor the voltage needs to be read between the output wire, pin 1 and the sensor ground, pin
2, of the connector. Using a suitable probe into the wire, the voltage should range from 0.6-2.4 V between
60 °-90 °C. If there is voltage but out of range replace sensor, if Zero volts is indicated continue with step
B.
B. Remove the connector and check the sensor using a suitable multi-meter. Measure the resistance across
the sensor terminals, the resistance should vary between 8-10kΩ@-10°C, 2.2-2.7kΩ@20°C and 0.29-
0.36kΩ@80°C. Check for a short to ground between each sensor terminal and the engine block, an open
circuit should be recorded on each terminal. If any readings are incorrect replace the sensor. If the sensor
is okay continue with step 3.
3. Check wiring
A. Disconnect the sensor connector. With the keystart switch ON, measure the voltage at pin 1, +5 V should
be measured. If no voltage is measured check the wiring for continuity between Pin 1 of the sensor con-
nector and pin 11 of engine ECU connector X192. Repair wiring as required.
Check for voltage on Pin 2 , 0 V should be measured. If voltage is measured trace and repair short circuit
in wiring between Pin 2 of the sensor connector and Pin 6 of the engine ECU connector X192.
With the keystart OFF, also check for continuity of the wire between Pin 2 of the sensor connector and Pin
6 of the engine ECU connector X192, and for a short to ground. Trace fault and repair as required.
B. If the wiring is okay suspect a faulty engine ECU. Download engine software using the electronic service
tool and operate engine. If fault still occurs substitute engine ECU.
Series 1206 and above
Wiring harness - Electrical schematic frame 04 (A.30.A.88-C.20.E.04)
POWER PRODUCTION - FUEL AND INJECTION SYSTEM
2 4/7/2006
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