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SPN 723 - FMI 2 (Fault Code 2322)

SPN723 FMI2
Engine Camshaft Speed/Position Sensor - Data Erratic, Intermittent, or Incorrect

ISB, ISC, and ISL - Engine Camshaft Speed/Position Sensor Circuit

CODES:
Fault Code: 2322
PID(P), SID(S): S064
SPN: 723
FMI: 2/2
Lamp: None

REASON: Engine Camshaft Speed/Position Sensor - Data Erratic, Intermittent, or Incorrect. Camshaft engine speed sensor intermittent synchronization.

EFFECT: None on performance.

Circuit Description:
The electronic 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.

Component Location:
-For ISC, ISL, and ISLe, the camshaft position sensor is located on the fuel side of the engine, in the gear housing, in front of the air compressor.
-For ISB, ISDe, and QSB 3.3, the camshaft position sensor is located on the front of the engine above the vibration dampener.

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

Shop Talk:
Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe™ Online for applicable fixes to the calibration stored in the ECM.

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 should 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.

Problems that can cause this fault:
• 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.


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