Cummins ISB4.5 CM2150 Fault Code: 2322 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 a 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 passes 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.

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

Conditions for Setting the Fault Codes
The ECM detects an intermittent loss of the camshaft speed/position sensor signal.

Action Taken When the Fault Code is Active
-The ECM logs the fault code when the diagnostic runs and fails.

Conditions for Clearing the Fault Code
– To validate the repair, start the engine and let it idle for 1 minute.
-The ECM will turn off the amber CHECK ENGINE light and the fault code will go inactive immediately after the ECM detects a valid signal from the camshaft speed/position sensor.
-This fault code can also be cleared with INSITE™ electronic service tool.

The ECM will set the fault code inactive after the ECM detects a valid signal from the camshaft speed/position sensor.

Shop Talk
During engine operation, the ECM monitors the secondary speed sensor (camshaft speed sensor) signal. Fault Code 778 will become active and light the yellow lamp if the signal from the secondary speed sensor is not present or degraded for more than 3 continuous seconds. If over a period of time the ECM detects several incidents of a loss of the secondary speed sensor signal, but the signal loss is short in duration, this fault code will become active. Since the secondary engine speed signal is not used for normal engine operation, a vehicle operator could possibly not notice any symptoms related to this problem.

This fault code becomes active whenever the ECM detects a persistent loss of the secondary engine speed sensor signal over a short period of time.

This fault becomes inactive at each key ON or if the ECM does not detect a loss of the secondary engine speed sensor signal for at least 20 minutes.

Possible Causes
-Intermittent loss of primary speed sensor signal; the most likely cause is an intermittent open or short circuit that can be experienced with speed sensor connector problems
-Sensor air gap that is marginally too small or too large, or target wheel exhibits excessive runout.

Actions to take if this fault is intermittent:
-Look for intermittent engine harness connections in the secondary engine speed sensor circuit
-Look for loose connections at the ECM connector where the pins can not be locked into the socket
-Look for places where the engine harness has worn into a nearby component causing an intermittent short circuit
-Look for pin wear at the speed sensor
-Inspect the target wheel for damage.