Usage:
System Operation
The ECM Main Engine Speed Sensor determines engine speed by magnetically detecting the teeth on the flywheel starter ring gear. The ECM will not try to start the engine (either energize the shutoff solenoid or move the BTM) until it senses an engine speed signal. Engine speed is determined by the frequency, not the voltage, of the engine speed sensor output signal. The output frequency should be between 0 and 5 kHz. The sensor is supplied with 8 volts DC from the ECM.
The 3408/3412 High Performance Marine Engine uses two speed sensors: one is the MAIN engine speed sensor and the other is the BACKUP engine speed sensor. If the main engine speed sensor signal is not present, the backup engine speed sensor signal will be used and the operator will be warned about the main speed sensor failure.
NOTE: When troubleshooting main speed sensor, disconnect the backup speed sensor from the system at P16/J16.
Schematic
Diagnostic Codes
Functional Test
Adjustment
1. Adjust clearance between the flywheel and the electronic sensor as follows:
a. Install electronic sensor until it makes contact with the flywheel.
b. Back out electronic sensor 270 ± 15 degrees.
2. Tighten locknut to a torque of 13.5 ± 1.0 N·m (120 ± 9 lb in).