RING-SLIP 8U4780 - Caterpillar

Illustration 1 g02351777
Schematic for the Right Hand Joystick Control sensorNote: The sensor is not directly connected to the frame ground. The sensor return connects to the ECM, and the ECM connects the sensor return to frame ground internally.This diagnostic code is for the Right Hand Joystick Control sensor for left and right motion. An FMI 03 indicates the machine ECM has determined the sensor output signal voltage is above normal. Possible causes for this diagnostic code are:
A failed sensor power supply.
A failed or disconnected sensor.
There is an open wire in the sensor circuit.
The sensor output signal is shorted to +battery.
The machine ECM may have failed, but is unlikely.Note: Poor connections are often the cause of a problem in electrical circuits. Before performing this procedure, inspect all the machine 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. Correct any problems found with any of the connections. Verify the diagnostic code CID 1128 FMI 03 is still active, before continuing with this procedure.Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes now, but clear those codes when the original diagnostic code has been corrected. Test Step 1. CHECK SENSOR POWER.Note: The Right Hand Joystick Control sensor is a PWM sensor. PWM sensors will set an FMI 03 code if the sensor power supply has failed. Check if a CID 1127 FMI 03 is also present, along with CID 1128 FMI 03. If that is true, perform Test Step 1. If not, skip Test Step 1, and go to Test Step 2.
Turn the disconnect switch and the key start switch to the ON position.
Insert the Multimeter Probe leads into the back of the Right Hand Joystick Control sensor connector and measure the voltage between contact 1 (M947-OR) and contact 2 (M948-BR).Expected Result:The voltage is 12.0 DCV.Results:
YES - The voltage is 12.0 DCV. The voltage is correct. Go to Test Step 2.
NO - The voltage is not 12.0 DCV. Repair: Reference the complete Electrical Schematics for the machine and investigate the ECM 12.0 DCV power supply problem. After correcting that problem, check if the diagnostic code CID 1128 FMI 03 is still active. If the CID 1128 FMI 03 code is still active, go to Test Step 2. Test Step 2. CHECK THE SENSOR.
Turn the disconnect switch and the key start switch to the OFF position.
Disconnect the machine harness connector from the Right Hand Joystick Control sensor.
In the sensor harness connector, insert a jumper wire between the contact for wire M962-YL and the contact for wire M948-BR in the connector.
Turn the disconnect switch and the key start switch to the ON position.
Observe the status of the CID 1128 FMI 03 diagnostic code. Expected Result:The CID 1128 FMI 03 code stays active. Results:
YES - The CID 1128 FMI 03 code stays active. The sensor is not the problem. Go to Test Step 3.
NO - The CID 1128 FMI 03 code