Cummins ISX12 CM2250 (2010-12) Fault Code: 778 PID: SID 64 SPN: 723 FMI: 2 Engine Camshaft Speed/Position Sensor- Data Erratic, Intermittent, or Incorrect

Circuit Description
The engine control module (ECM) provides 5 volt supply to the engine camshaft speed/position sensor on the sensor supply circuit. The ECM also provides a ground on the sensor return circuit. The camshaft speed/position sensor provides a signal to the ECM on the camshaft speed/position sensor signal circuit. This sensor generates a signal to the ECM as the camshaft speed indicator lobe moves past the sensor. The ECM interprets this signal into an engine speed reading and determines engine position. This sensor is used as a backup sensor if the primary engine crankshaft speed/position signal is lost.

Component Location
For ISX 15, the camshaft position sensor is located in the top of the gear housing, on the exhaust side. Refer to Procedure 100-002 in Section E.

For ISX 11.9, the camshaft position sensor is located in the top of the front gear housing, on the fuel side. Refer to Procedure 100-002 in Section E.

For ISC and ISL the camshaft position sensor is located on the fuel side of the engine, in the gear housing, in front of the air compressor. Refer to Procedure 100-002 in Section E.

For ISB the camshaft position sensor is located on the front of the engine, above the vibration dampener. Refer to Procedure 100-002 in Section E.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the engine is running.

Conditions for Setting the Fault Codes
The ECM detects a loss of the camshaft speed/position sensor while the engine is running.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.
Diesel exhaust fluid injection into the aftertreatment system is disabled.
Active and stationary regeneration of the diesel particulate filter will be disabled.
The exhaust gas recirculation (EGR) valve will be closed.
Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.
Conditions for Clearing the Fault Code
To validate the repair, start the engine and let it idle for 1 minute.
The fault code status displayed by INSITE? electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.
For on-board diagnostic (OBD) engines, the ECM will turn off the MIL after 3 consecutive trips where the diagnostic runs and passes.
The ?Reset All Faults? command in INSITE? electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk
Causes of this fault include:

Open or short circuit of the 5 volt supply, signal, or return wire in the engine harness.
Damaged or malfunctioning camshaft position sensor.
Damaged speed indicator lobe.
Sensor air gap that is too large or small.

Possible Cause:
1) Engine Wiring harness
2) Sensor failure
3) ECM calibration