- the optional fluid level sensor for the engine coolant
- the engine speed sensor
The GSC receives data directly from these sensors for monitoring purposes. The engine oil pressure and engine coolant temperature sensors are connected to the engine ECM for use in controlling fuel injection. The engine ECM also sends the data for the oil pressure and the coolant temperature to the GSC by the CAT data link for monitoring. Refer to Troubleshooting, SENR1003, "3500B EPG Engines" information on the oil pressure and coolant temperature sensors.
Fluid Level Sensor (Engine Coolant)
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| Illustration 1 | g00474732 |
The fluid level sensor is optional and the sensor is an input of the GSC. The sensor tells the GSC when the engine has lost coolant. The GSC uses the information from the sensor in order to determine when a fault for a low coolant level exists. The sensor is usually mounted near the top of the engine radiator. The exact location depends on the engine model.
The fluid level sensor sends a ground signal to the GSC in order to indicate a normal level. The sensor sends a signal of 5 DCV in order to indicate a low level. The signal wire of the sensor connects to connector contact 13 of the GSC. The sensor is supplied with the power at connector contact "A" from the GSC (connector contact 9).
There are three setpoints that are related to the loss of engine coolant. The setpoints P04, P05 and P06 are programmed into the GSC. See Systems Operation, "Setpoint Programming OP5".
Speed Sensor (Engine)
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| Illustration 2 | g00311291 |
The engine speed sensor is an input of the GSC. The sensor tells the GSC the engine speed. The GSC shows the engine speed on the lower display. Also, the GSC uses the information from the sensor for tasks. The tasks are included in the following list.
- activation of an engine overspeed shutdown
- terminating engine cranking
- determining the oil step speed
The engine speed sensor is mounted on the flywheel housing of the engine.
The sensor creates a sine wave signal from passing ring gear teeth at the rate of one pulse per tooth. The sensor sends a sine wave signal to the GSC. The frequency of the signal is in proportion to the speed of the engine. The GSC receives the sine wave signal and the GSC measures the frequency in order to determine the speed of the engine. The wires of the sensor connect to connector contacts 1 and 2 of the GSC within a shielded cable. One wire is grounded near the GSC.
There are four setpoints that are related to engine speed. The setpoints P09, P10, P11, and P12 are programmed into the GSC. See Systems Operation, "Setpoint Programming OP5".