SUPPORT AS 9U4894 - Caterpillar

Illustration 1 g03844575
Connections of the 5V Hydraulic Oil Level SensorThe 5V power supply provides power to the oil level sensor for the transmission. The FMI 04 is recorded when the ECU reads the voltage of the signal wire as being below normal and/or shorted to ground.The following is a list of possible causes for this diagnostic trouble code:
The sensor supply circuit is shorted to the ground.
A sensor has failed.
The ECU has failed. An ECU failure is unlikely.Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear these diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 0435 FMI 04 is active before performing this procedure.Note: Use a digital multimeter for the measurements in this procedure.Test Step 1. CHECK THE SENSOR
Turn the key start switch and the disconnect switch to the ON position.
Disconnect the machine harness from the sensor. Then, observe the status of the diagnostic code.Expected Result:The diagnostic code is not active.Results:
OK - The diagnostic code is not active. The harness circuit is correct. The sensor that was disconnected has failed.Repair: Replace the sensor.STOP
NOT OK - The diagnostic code is still active. The machine harness may be shorted to ground. Proceed to Test Step 2.Test Step 2. CHECK FOR A SHORT TO GROUND
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness from the ECU.
At the harness connector for the ECU, measure the resistance between frame ground and contact J1-31 (wire 126-RD) of the sensor supply circuit. Expected Result:The resistance is greater than 5000 ohms.Results:
OK - The resistance is greater than 5000 ohms. The harness circuit resistance is correct. The ECU may have failed.Repair: An ECU failure is unlikely. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, replace the ECU. Prior to replacing an ECU, always contact your Cat Dealer Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. Refer to Testing and Adjusting, KENR8292, "Electronic Control Unit - Replace" for more information.STOP
NOT OK - The resistance is less than 5000 ohms. The machine harness has failed.Repair: The 126-RD wire is shorted to ground in the machine harness. Refer to the complete Electrical System Schematic for your machine. Check all harness connectors that are in the power supply circuit. Ensure that the connectors are clean and secure. Repair the machine harness or replace the machine harness.STOP