Series 60 – Section 2.38 Knock Sensor and Signal Noise Enhancement Filter Module

Section 2.38
Knock Sensor and Signal Noise Enhancement Filter Module

For knock protection, the Series 60 natural gas engines are equipped with a Knock Sensor and Signal Noise Enhancement Filter (SNEF) module. The knock sensor is located at the left rear of the cylinder head. The SNEF module is mounted on the left side of the cylinder block. The SNEF module receives electrical signals from the knock sensor and sends electrical signals to the ECM indicating knock level. The ECM uses this information to determine if the engine is knocking and adjusts ignition timing, air fuel ratio and throttle plate to protect the engine from excessive knock. See Figure "Location of Knock Sensor and Signal Noise Enhancement Filter Module" .‪

1. Knock Sensor‪

2. SNEF Module‪

Figure 1. Location of Knock Sensor and Signal Noise Enhancement Filter Module

Listed in Table "Knock Sensor Diagnostic Codes for the Series 60G Engine" are the knock sensor and knock interface module diagnostic codes:‪

Description ‪	Voltage ‪	SID ‪	FMI ‪	Information ‪
Knock Control‪	HIGH‪	S76‪	3‪	Indicates that the knock sensor input to the ECM has exceeded 95% (normally >4.75 volts) of the sensor supply voltage. This diagnostic is typically detected when there is an open sensor return circuit or the sensor signal circuit is shorted to the sensor +5 volt supply.‪
Knock Control‪	LOW‪	S76‪	4‪	Indicates that the knock sensor input to the ECM has dropped below 5% (normal < 0.25 volts) of the sensor supply voltage. This diagnostic is typically detected when there is:- An open sensor signal circuit- An open sensor +5 volt supply circuit- The sensor signal is shorted to the sensor return circuit or to ground- The sensor +5 volt supply is shorted to sensor return circuit or to ground.‪
Knock Control‪	HIGH‪	S76‪	0‪	Indicates that the knock interface module has detected that the engine knock level has exceeded the first level of the recommended engine operational range.‪
Knock Control‪	MECHANICAL FAULT‪	S76‪	7‪	Indicates that the knock interface module has detected that the engine knock level has exceeded the second level of the recommended engine operational range.‪

Section 2.38.1
Replacement of Knock Sensor and Signal Noise Enhancement Filter Module

The knock sensor and SNEF module are non-serviceable and each should be replaced as a unit. No adjustment is required.‪

Section 2.38.2
Removal of Knock Sensor and Signal Noise Enhancement Filter Module

Remove the knock sensor as follows:‪

1. Disengage the locking tang on the single wire connector. Grasp the body of the connector and gently pull it from the socket.
2. Use the appropriate wrench on the hex portion of the sensor and unscrew it from the fitting.

Remove the SNEF module as follows:‪

1. Disengage the locking tang on the wire connector. Grasp the body of the connector and gently pull it from the socket.
2. Remove the two bolts attaching the SNEF module to its mounting bracket.

Section 2.38.3
Installation of Knock Sensor and Signal Noise Enhancement Filter Module

Install the knock sensor as follows:‪

1. Screw the sensor into the cylinder head. Torque to 16-22 N·m (12-16 lb·ft).
2. Engage locking tang.

Install the SNEF module as follows:‪

1. Install the SNEF module to its mounting bracket and attach with two mounting bolts.
2. Engage locking tang.