SENSOR GP-SPEED 7C1897 - Caterpillar

The 3408 & 3412 High Performance Marine Engines are an electronically controlled engine. The Electronic Control Module (ECM) controls fuel rate instead of using flyweights and linkages. The electronics also replaces the mechanical fuel/air ratio, torque control group and various adjustment screws.The ECM uses several sensors as inputs to control the rack. The ECM determines the position the rack should be at then varies the voltage to the Brushless Torque Motor (BTM) to move the rack to the desired position. The rack position sensor tells the ECM when the rack is at the determined position.Coolant Level Sensor
The Coolant Level Sensor operates as a low coolant level indicator. The sensor output will change status with the presence or absence of fluid at the sensing probe tip.* Coolant Level Sensor Outputs (All voltages are DC and referenced to -Battery Bus Bar at the ECM Connector J14/P14, pin-21)A. Fluid Present Output voltage = 0.5 VDC MAXIMUM.B. Fluid Absent Output voltage = 4.1 VDC MINIMUM.* Coolant Level Sensor Mounting GuidelinesThe sensor is supplied with thread sealant applied to the threads. No other tape or sealant should be applied when mounting. Torque specifications are 30 5 N m (22 4 lb ft).Boost Pressure Sensor
The Boost Pressure Sensor is an absolute pressure sensor measuring inlet air manifold pressure. The difference between the pressure measured by this sensor (inlet air manifold pressure) and atmospheric pressure is boost pressure.Boost pressure, as displayed on an Electronic Service Tool and communicated over the data link, has 100 kPa (14.5 psi) subtracted from the absolute value for all 3408 & 3412 High Performance Marine Engines. The sensor measures pressure from 0 to 690 kPa (0 to 100 psi). The sensor power is supplied by the ECM with 5 VDC.Atmospheric Pressure Sensor
The Atmospheric Pressure Sensor is an absolute pressure sensor measuring crankcase pressure. Both the boost (inlet manifold) pressure and oil pressure communicated to Electronic Service Tools and over the data link are calculated by subtracting the Atmospheric Pressure Sensor reading.The Atmospheric Pressure Sensor measures pressure from 0 to 116 kPa (0 to 16.8 psi). The sensor is supplied by the ECM with 5 VDC.Coolant Temperature Sensor
The standard Coolant Temperature Sensor can be used for monitoring high coolant temperatures in addition to enhancing cold starting.Coolant Temperature is used to indicate "Cold Mode" operation, Cold Elevated Idle, and for Engine Monitoring.Cold Mode Operation
Cold Mode Operation is activated whenever the coolant temperature is below 60°C (140°F). During Cold Mode the start rack is limited to 10mm during engine start-up to 500 rpm.The engine will remain in a Cold Mode state for a maximum of 5 minutes or when the engine speed is above 1200 rpm the Cold Mode will deactivate.Oil Pressure Sensor
The Oil Pressure Sensor is an absolute pressure sensor measuring oil pressure in the oil gallery. The difference between the pressure measured by this sensor (oil pressure) and atmospheric pressure is oil pressure as displayed on an Electronic Service Tool and communicated over the data link.The lack of oil