ELECTRONICS GP-MONITOR 2074457 - Caterpillar

Illustration 1 g02027415
Left Joystick Thumbwheel Modulation Control sensor circuit schematic
This diagnostic code is for the Left Joystick Thumbwheel Modulation Control sensor. An FMI 03 diagnostic code means the Machine ECM has determined the sensor output signal voltage is above the normal limit. Possible causes of this diagnostic code are listed below:
Failed sensor power supply.
Failed sensor.
Open sensor signal output wire.
Sensor signal output wire shorted to +battery.
Failed Machine ECM, but most unlikely.Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes now, but clear those codes after the original diagnostic code has been corrected. Note: Poor connections are often the cause of a problem in electrical circuits. Before performing this procedure, inspect all of the harness connectors involved in the circuit. Verify that all of the connections in the circuit are clean, secure, and in good condition. If a problem is found with any of the connections: correct the problem and verify that diagnostic code CID 1657 FMI 03 is still active, before performing the following procedures. System Response:When this diagnostic code occurs, there is no warning on the monitor. The "thumbwheel" control of the joystick will be inoperative.Test Step 1. VERIFY THE +8 VDC SUPPLY.
Turn the disconnect switch and the key start switch to the ON position.
Do not disconnect any of the machine harness connectors at this time.
At the harness connector for the Left Joystick Thumbwheel Modulation Control sensor, measure voltage from contact 1 (wire E472-GN(Green)) to contact 2 (wire 235-BK(Black)) on the sensor connector. Expected Result:The voltage is 8.0 0.5 VDC. Results:
YES - The voltage is 8.0 0.5 VDC. Go to Test Step 2.
NO - The voltage is not 8.0 0.5 VDC. There is a problem with the +8 VDC power supply.Repair: Refer to the complete electrical schematics for the machine. Investigate the ECM +8 VDC power supply problem.After +8 VDC power supply problem is repaired, check if the 1657 FMI 03 diagnostic code is still active. If the diagnostic code is still active, go to Test Step 2.Test Step 2.