CM850 Electronic Control System – FAULT CODE 2322

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Overview

Backup Engine Speed/Position Sensor Number 2 Circuit SMALL | MEDIUM | LARGE

Circuit Description

The camshaft engine position sensor provides engine position information to the electronic control module (ECM). The sensor is powered by (+) 5 VDC. The sensor generates the signal by sensing the movement of target teeth machined into a tone wheel that is mounted to the camshaft.

Component Location

The camshaft position sensor is located below the fuel pump in the back of the gear housing. Refer to Procedure 100-002 in Section E for a detailed component location view.

Shop Talk

During engine operation, the ECM monitors the secondary speed sensor (crankshaft speed sensor) signal. Fault Code 778 will become active and light the yellow lamp (marine does not use lamps) if the signal from the secondary speed sensor is not present or degraded for more than three 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.

Failures that can cause this fault:

• Intermittent loss of primary speed sensor signal, the most likely cause is an intermittent open or short circuit as 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.

Refer to Troubleshooting Fault Code t05-2322