BEARING-MAIN 4W8093 - Caterpillar

System Operation Description:The engine speed sensor provides information about the engine speed to the Electronic Control Module (ECM). The sensor is mounted on the flywheel housing. The ECM uses the signal from the sensor in order to govern the speed of the engine.
Illustration 1 g01045708
Engine speed sensor for the ECMThe engine speed sensor is a powered type of sensor. The sensor receives 10 VDC from the ECM. This voltage is shared with the inlet manifold temperature sensor.The signal from the engine speed sensor varies in voltage and in frequency. The level of the signal varies between 0 VDC and 14 VDC. The frequency of the signal can be measured with the following test equipment:
Oscilloscope
An AC voltmeter that measures the frequency of the signalThe ECM monitors the signal from the engine speed sensor for these faults:523-00 Engine Overspeed - The engine speed is greater than 2000 rpm. The ECM will send a shutdown command to the EIS control module via the Cat data link.523-02 Noisy Engine Speed Signal - The engine rpm is greater than 400 rpm and the ECM has measured an acceleration rate that is greater than 2.5 rpm per millisecond. The engine will continue to run. However, operation of the engine may be degraded.523-11 No Engine Speed Signal - The EIS control measures an engine speed that is greater than 100 rpm. The ECM measures an engine speed that is less than 75 rpm. The ECM will send a shutdown command to the EIS control module via the Cat data link.
Illustration 2 g01045516
Schematic diagram of the engine speed sensorThe engine is equipped with a remote control panel that includes a status control module and air/fuel ratio control.
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Schematic diagram of the engine speed sensorThe engine is configured for Canadian Standards Association (CSA). The engine is equipped with an optional remote control panel with air/fuel ratio control.Test Step 1. Inspect the Electrical Connectors and the Wiring
Set the engine control to the OFF/RESET mode. Remove the electrical power from the engine.Note: For the following steps, refer to Troubleshooting, "Inspecting Electrical Connectors".
Thoroughly inspect each of the following connectors:
Connectors for the EIS control module
Connectors for the engine speed sensor
Illustration 4 g01045730
Harness side of the P1 connector (P1-2) 10 VDC for the engine speed sensor (P1-3) Ground for the sensors (P1-31) Engine speed signal
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit for the engine speed sensor.
Check the harnesses and the wiring for abrasion and for pinch points from the engine speed sensor to the ECM.Expected Result:The connectors, pins, and sockets are connected properly. The connectors and the wiring do not have corrosion, abrasion, or pinch points.Results:
OK - The components are in good condition with proper connections. Proceed to Test Step 2.
Not OK - The components are not in good condition and/or at least one connection is improper.Repair: Perform the necessary repairs and/or replace parts, if necessary.STOPTest Step 2. Check for an Open Circuit
Disconnect the following connectors:
J1 connectors for the ECM
Connector for the engine