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| Illustration 1 | g01280481 |
Speedometer/tachometer circuit | |
The components of the speedometer/tachometer circuit are the Power Train Electronic Control Module (Power Train ECM), Engine Electronic Control Module (Engine ECM), Caterpillar Monitoring System ECM, transmission output speed sensor, primary speed/timing sensor, secondary speed/timing sensor and speedometer/tachometer module.
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| Illustration 2 | g01261573 |
Operator station (under seat) (1) Power Train ECM | |
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| Illustration 3 | g01259618 |
Left side view of engine (2) Engine ECM | |
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| Illustration 4 | g03739346 |
(3) Caterpillar Monitoring System ECM (behind display) | |
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| Illustration 5 | g01023858 |
Transmission compartment (4) Transmission output speed sensor | |
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| Illustration 6 | g01259620 |
Left side view of engine (5) Primary speed/timing sensor (not shown) | |
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| Illustration 7 | g01259621 |
Left side view of engine (6) Secondary speed/timing sensor | |
With the battery disconnect switch in the ON position, 24 V power is supplied from the batteries via circuit breaker 5 to Power Train ECM (1) and via circuit breaker 1 to Engine ECM (2) .
When the key start switch is in the ON position, 24 V power is supplied from the batteries via circuit breaker 14 to Power Train ECM (1), via circuit breaker 6 to Engine ECM (2), and via circuit breaker 7 to Caterpillar Monitoring System ECM (3) .
Transmission output speed sensor (4), primary speed/timing sensor (5), and secondary speed/timing sensor (6) are magnetic pick-ups. An electrical pulse is generated whenever the gear tooth interrupts the magnetic field. This signal is then sent to the relative ECM.
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| Illustration 8 | g01258754 |
(7) Speedometer/tachometer module (behind dash) | |
With the machine moving, the transmission output speed sensor generates a signal that is sent to Power Train ECM (1). The machine ground speed is determined by Power Train ECM (1) and sent to Caterpillar Monitoring System ECM (3) via the CAT Data Link.Caterpillar Monitoring System ECM (3) sends a signal to speedometer/tachometer module (7) to display the ground speed.
While the engine is running, primary, and secondary speed/timing sensors (5) and (6) generate a signal that is sent to Engine ECM (2). Engine ECM (2) determines the engine rpm. Engine ECM (2) sends a signal via the CAT Data Link to Caterpillar Monitoring System ECM (3). Caterpillar Monitoring System ECM (3) sends a signal to speedometer/tachometer module (7) to display the engine speed.