PLUG 8S8005 - Caterpillar

Illustration 1 g03423037
This diagnostic code is associated with the Generator Speed Sensor. The FMI 02 means that the ECM has determined that the signal frequency or the signal pulse width is not within the expected range.The generator speed sensor is a Hall effect sensor that provides an input signal to terminal "J2-41" on the Right Operator ECM (MID 157). The sensor measures the speed (rpm) of the generator motor. The machine ECM uses this information to maintain the regulated speed of the generator through closed loop control logic.Note: The right operator ECM is located under the right operator seat.The possible causes of this diagnostic code are listed below:
The speed sensor is not installed correctly.
The sensor has failed.
Intermittent connections or poor harness connections.
A malfunction in the sensor power supply circuit.
The Right Operator ECM has failed. This situation is unlikely..Note: An ECM is programmed to detect malfunctions of the ECM power supplies. Check if the ECM has already triggered a diagnostic code for the inboard 8 VDC power supply (CID 41). If the ECM has triggered such a code, troubleshoot that code first. Note: Poor connections are often the cause of a diagnostic fault. Before performing this procedure, inspect the harnesses and connectors involved in the circuit. Make sure to verify that all of the connections in the circuit are clean, secure, and in good condition. Verify the CID 2774 - FMI 08 diagnostic code is still active, before continuing with this procedure.Note: Before performing the following test steps, check to see that the speed sensor is mounted securely. If the speed sensor mount is correct and the CID 2774 FMI 2 diagnostic code is active, proceed to Test Step 1.Note: Use the 146-4080 Digital Multimeter Gp for the measurements in this procedure.System Response:When this diagnostic code is active, the following occurs:
The generator is disabled.
The machine operates in open loop.
No power for the auxiliary outlets on the rear of the machine.
No power for the electric screed.
The operator station fault lamp is active.Note: The following test procedures may create other diagnostic codes. Ignore all the created diagnostic codes now, but clear all those codes after the cause for the original diagnostic code has been corrected.Test Step 1. CHECK THE POWER SUPPLY CIRCUIT AT THE SENSOR
The machine harness remains disconnected from the sensor.
Turn the key start switch to the ON position.
At the machine harness for the sensor, measure the voltage. Measure the voltage from contact 1 (wire 144-GN) and contact 3 (wire C234-BK).Expected Result:The voltage that is measured is between 8 0.5 VDC.Results:
OK - The power supply circuit is correct. Proceed to Test Step 2.
NOT OK - The power supply circuit is open between the sensor and the ECM.Repair: Refer to the complete Electrical System Schematic for the machine. Examine all of the connections in the sensor power supply circuit. Make sure all the connections are clean, free of rust, secure, and in good condition. Repair or replace the machine harness as needed. STOPTest Step 2. INSPECT THE SENSOR.
The key start