ELECTRONICS GP-POWER TRAIN 2074456 - Caterpillar

Illustration 1 g02027415
Schematic of the "Left Joystick Thumbwheel Modulation" control
This diagnostic code is recorded when the Machine ECM reads the voltage of the circuit for the "Thumbwheel" as being below normal. The signal circuit of the "Thumbwheel PWM" output may be shorted to ground.The possible causes of this diagnostic code are listed below:
The signal circuit for the "Thumbwheel Modulation" control is shorted to ground.
The "Thumbwheel Modulation" control has failed.
The Machine ECM has failed. This is unlikely. Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected.Note: Ensure that the diagnostic code of CID 1657 FMI 04 is active before performing this procedure. System Response:When this diagnostic code occurs, there is no warning on the monitor. The "Thumbwheel Modulation" control will be inoperative.Test Step 1. CHECK THE "THUMBWHEEL" CONTROL.
Turn the disconnect switch and the key start switch to the ON position.
Ensure that the diagnostic code is active.
Observe the status of the diagnostic code. Disconnect the joystick from the machine harness. Expected Result:The CID 1657 FMI 04 diagnostic code remains active. Results:
OK - The diagnostic code remains active. The "Thumbwheel Modulation" control is correct. Proceed to Test Step 2.
NOT OK - The diagnostic code is no longer active. The "Thumbwheel Modulation" control has failed.Repair: Replace the entire joystick handle.STOPTest Step 2. CHECK THE WIRING HARNESS OF THE "THUMBWHEEL MODULATION" CONTROL FOR A SHORT TO GROUND.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness from the joystick.
Disconnect machine harness connectors from the Machine ECM.
At the machine harness connector for the Machine ECM, measure the resistance from the signal contact J1-38 (wire E474-OR(Orange)) of the machine harness to all possible sources of ground. Measure the resistance to all contacts that are used in the J1 and J2 harness connectors. Expected Result:Each resistance measurement should be greater than 5000 ohms.Results:
OK - Each resistance measurement is greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 3.
NOT OK - One or more resistance measurements is not correct. There is a short in the machine harness. The short is between signal contact J1-38 (wire E474-OR(Orange)) and the circuit with the low resistance measurement. Repair the machine harness or replace the machine harness.STOPTest Step 3. CHECK IF THE DIAGNOSTIC CODE REMAINS.
Inspect the contacts of the harness connectors and clean the contacts.
Reconnect all harness connectors.
Turn the disconnect switch and the key start switch to the ON position.
Enter the service mode of the Monitoring System and clear all of the inactive diagnostic codes.
Operate the machine.
Check the status of the CID 1657 FMI 04 diagnostic code. Expected Result:The CID 1657 FMI 04 diagnostic code is not active. Results:
YES - The CID 1657 FMI 04 diagnostic code is not active. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected