3.2.351. SPN 520385, FMI 31, ECU 2 Crankshaft speed sensor signal missingΒΆ

Description

The crankshaft speed signal is repeated by the ECU 1 to the ECU 2. The angular position evaluation module in the ECU 2 expects a defined sequence of pulses from the ECU 1. If no signal is received by the ECU 2, the system reports a fault.

Possible causes are:

  • The signal wiring is defective.
  • An external electromagnetic disturbance is affecting the sensor signal.

Reaction in EEM

The FC is stored and the warning lamp is activated. The CAN message indicates active fault. Engine power will be reduced (Degradation Level 2). The engine starting may take longer than normally, and running may be poor due to missing/incorrect information for the injection timing control. The ECU 2 runs with the camshaft speed sensor signal.

Solution

First save the error log and then erase it. Restart the ECU after erasing the error log. If the fault occurs again during the next driving cycle, check the following paths:

  • Check the repetition signal wiring, the connectors and the contact surfaces of the connector pins (possible oxidation).

The crank repetition signal pin numbers:

ECU 1   2.44 Output
ECU 2   2.66 Input

Also for correct repetition reference signal a jumper is needed between the ECU pins:

ECU 1   2.09
ECU 2   2.65
  • Look for possible electromagnetic noise sources on or close to the vehicle, which are disturbing the signal (devices using or carrying high currents, high voltages or strong magnetic fields).