Cummins ISB CM850 (2003-06) Fault Code: 115 PID: 190 SPN: 612 FMI: 2 Engine Magnetic Crankshaft Speed/Position Lost Both of Two Signal – Data Erratic, Intermittent, or Incorrect. The ECM has detected that the primary engine speed sensor and the backup engine speed sensor signals are reversed.

The main engine speed sensor (crankshaft position sensor) and the backup engine speed sensor (camshaft position sensor) are located in close proximity to one another. The same sensor is used in both locations. (Connector key is the same.) A P-clip on the engine wiring harness prohibits the harness connectors from being connected to the incorrect sensors. However, if the P-clip is omitted, it is possible to plug the wiring harness connectors into the incorrect sensors. If this occurs, the ECM will detect the problem and the engine will not start. Once the connector problem is corrected, the engine can be started and the fault code will become inactive.

The sensor return configuration for Euro 4 ISB engines has been changed for automotive wiring harnesses manufactured from February 2012 onward. The new style wiring harnesses can be be identified using the method below:

1)Disconnect the ECM connector
2)Disconnect the camshaft position sensor
3)Disconnect the intake manifold pressure/temperature sensor
4)Check for continuity between the intake manifold pressure/temperature sensor RETURN pin, and the camshaft position sensor RETURN pin
5)Check for continuity between ECM pin 47 and the camshaft position sensor RETURN pin.
6)Use the table below to determine which harness is fitted to the engine.

NOTE: QSB engines, all C series engines, and all L series engines are not affected by this change.

Possible repairs:

1)Make sure that the main engine speed sensor (crankshaft position sensor) and the backup engine speed sensor (camshaft position sensor) are connected to the engine wiring harness correctly.