FMI 8 – Abnormal frequency, pulse width or period
Fault code explanation: Faulty sensor / Faulty sensor circuit
Fault indication: DCU: Engine warning in DCU display.
CIU: Flash code
Electrical fault: 2.4
Value fault: None.
Symptom: Engine is difficult to start, uses only cam sensor.
Conditions for fault code: Incorrect flywheel sensor signal.
Possible reason: • Incorrectly mounted flywheel sensor.
• Electrical interference in the flywheel signal.
Suitable action: 1
Check wiring between flywheel sensor and EMS2.
2 Check the installation of the flywheel sensor.
3 Attempt to localize the source of interference.
4 Check and clean the flywheel sensor.
5 Check the contact pressure in socket 37 and 38 in engine connector A.
a Connector A
b Engine speed sensor, crankshaft
The flywheel sensor is an inductive sensor. The fly-
wheel sensor is used to monitor engine speed. It is
also used to measure the cylinder acceleration. The
three times eighteen depressions for one
rotation. These depressions are detected by the fly-
wheel sensor and generate a pulsed signal which the
engine control unit uses to detect flywheel rotation
speed. Two cylinders share one sector of the depres-
sions (cylinders 1 and 6, 2 and 5, 3 and 4) on the fly-
wheel. This means that it is not possible to know which
Checking flywheel sensor wiring page 179
Checking flywheel sensor page 180
30-2 Fault Tracing
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