TM 5-3895-373-201.18.8. STE/ICEandDiagnosticConnectorCircuit.The STE/ICE and diagnostic connector circuit consists ofa diagnostic connector assembly, four pressuretransmitters, two pressure differential switches, atachometer generator, temperature sensor, and currentshunt.The diagnostic connector assembly (DCA box) containsthe electrical connector to mate the paving machinediagnostic sensors with the STE/ICE Vehicle Test Meter(VTM). The DCA box provides the power for the test set.Within the DCA box is the vehicle identification coderesistor to identify to the vehicle test meter the type ofinternal combustion engine being tested. The DCA boxcontains two toggle switches. The ENGINE CRANKswitch disables the engine fuel shutoff solenoid toprevent the engine from starting during certain tests.The ZERO OFFSET switch is used during enginecoolant temperature tests to set the sensor to zero. 24VDC from the paving machine is sent to the DCAconnector on the DCA box for power for the vehicle testmeter.Four pressure transmitters are used on the pavingmachine to check engine fuel pressure, engine oilpressure, turbosupercharger outlet pressure, and aircleaner outlet pressure. These sensors are as follows:Fuel and oil pressure transmitters measure theengine fuel lift pump and engine oil pump outletpressures.The turbosupercharger outlet pressuretransmitter measures the discharge pressure ofthe turbosupercharger.The air cleaner pressure transmitter measuresair cleaner outlet pressure in respect to theambient air pressure.Two differential pressure switches are used to measurethe restriction of engine fuel and engine oil through thefilters. This is used to determine if the filters are cloggedor need changing. The pressure difference will displayas a PASS/FAIL indication.The tachometer generator used to measure enginespeed is a pulse detector. The detector is mounted onthe timing gear cover and is driven by the timing gears.Engine speed is measured as a series of pulses throughthe timing gears.The engine coolant temperature transducer is a resistivetemperature sensor installed on the engine near thethermostat housing. It measures the engine coolanttemperature.Engine current measurements are made using a currentshunt. Starter tests and battery resistance tests use thecurrent shunt as a detector.Resistance tests are performed by the voltage testmeter. These consist of battery internal resistance,starter circuit resistance, and battery resistance change.Voltage measurements are performed by the voltage testmeter. These consist of starter voltage during cranking,alternator output voltage, and alternator field voltage.DIAGNOSTICS CONNECTOR ASSEMBLY1-33
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