FMI 5 – Current below normal or open circuit
Fault code explanation: Faulty sensor / Fault in sensor circuit
Fault indication: DCU: Engine warning in DCU display.
CIU: Flash code
Electrical fault: 3.7
Value fault: 5.8
Conditions for fault code: The voltage on pin A31 in the engine control unit exceeds 4,95 Volt.
Possible reason: • Open circuit in the oil temperature signal cable.
• Open circuit in the oil temperature negative cable.
Fault in sensor.
Suitable action: 1 Check the cable harness between the sensor and the EMS2.
2 Check the contact pressure in socket 31 in the engine connector A and
in socket 10 in engine connector B.
3 Check the sensor.
a Connector A
b Connector B
Oil temperature and level
temperature and the oil level sensor is a com-
bined sensor. The oil temperature sensor consists of
a thermistor which forms a closed circuit with an inter-
nal resistor in the engine control unit (EMS2). The
thermistor resistor changes in a non-linear manner,
depending on the oil temperature. The EMS2 pro-
vides the circuit with a reference voltage of +5 Volt via
pin 31 in connector A. The EMS2 measures the volt-
age drop over the thermistor via pin 18 and pin 31 on
the EMS2. Pin 4 on the sensor is connected to battery
negative via pin 18 in connector B on the EMS2. When
the oil is cold, the thermistor resistance is high and the
EMS2 senses a high voltage drop. As the oil warms
up, the resistance in the thermistor falls and the volt-
age drop across it falls.
Please refer to the table, “resistance/temperature” in
this fault code chapter.
Checking negative cable, oil temperature
switch page 165
Checking signal cable, oil temperature
switch page 166
Checking oil temperature sensor page 167
30-2 Fault Tracing
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