MOTOR GP- 2885123 - Caterpillar

Illustration 1 g02351750
Schematic for the Left 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 associated with the Left Hand Joystick Control sensor for left and right movement. An FMI 04 indicates the machine ECM has determined the sensor output signal voltage is below normal. Possible causes for this diagnostic code are:
The sensor has failed.
The sensor output signal is shorted to ground.
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 1126 FMI 04 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 THE SENSOR
Turn the disconnect switch and the key start switch to the OFF position.
Disconnect the harness connector from the Left Hand Joystick Control sensor.
Turn the disconnect switch and the key start switch to the ON position.
Observe the status of the CID 1126 FMI 04 diagnostic code. Expected Result:The CID 1126 FMI 04 code stays active. Results:
YES - The CID 1126 FMI 04 code stays active. The sensor is not the problem. Go to Test Step 2.
NO - The CID 1126 FMI 04 code is no longer active and has been replaced by a CID 1126 FMI 03 code. The sensor has failed. Repair: Replace the sensor. The new sensor will need to be calibrated. Go to Test Step 3.Test Step 2. CHECK THE SENSOR CIRCUIT FOR A SHORT.
Turn the key start switch and the disconnect switch to the OFF position.
The sensor connector remains disconnected.
Disconnect both the J1 and J2 harness connectors from the machine ECM.
At the ECM harness connectors, measure the resistance from the contact J1-52 (wire C472-GN) to all of the other contacts that are used in both the J1 and J2 ECM harness connectors. Expected Result:Each resistance measured is more than 5000 ohms. Results:
YES - Each resistance measured is more than 5000 ohms. The machine harness is correct. Go to Test Step 3.
NO - A resistance measured is not more than 5000 ohms. There is a short in the machine harness. The short is between J1-52 (wire C472-GN) and the circuit with the low resistance.Repair: Repair or replace the harness. Go to Test Step 3.Test Step 3. CHECK THE DIAGNOSTIC CODE STATUS.
Reconnect all harness connectors. Make sure that the connectors are fully seated. Observe that the clips on each connector are securely fastened.
Turn the disconnect switch and the key start switch to the ON position.
Clear all inactive diagnostic