SEAL ASSEM 5H0427 - Caterpillar

Illustration 1 g02145600
Connection of the 8 VDC power supply
This diagnostic code is associated with the 8 VDC power supply. The FMI 04 is recorded when the ECM reads the voltage of the supply circuit as lower than the normal voltage. The possible causes of this diagnostic code are listed:
A sensor has failed.
The voltage supply is shorted to a ground source.
The ECM has failed. An ECM 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 0041 - FMI 04 is active before performing this procedure.Note: Use a digital multimeter for the measurements in this procedure.Test Step 1. Check the sensors
Turn the key start switch and the disconnect switch to the ON position.
One at a time, disconnect the machine harness from a sensor. Observe the status of the diagnostic code. Expected Result:The diagnostic code becomes inactive when a sensor is disconnected.Results:
YES - The diagnostic code is not active when a certain sensor is disconnected. The harness circuit is correct. The sensor has failed.Repair: Replace the sensor.STOP
NO - The diagnostic code is still active. The machine harness may be shorted to ground. Proceed to Test Step 2.Test Step 2. Check the harness for a short to groundThe J1 machine harness connector remains disconnected from the ECM.
Turn the disconnect switch and the key start switch to the OFF position.
Disconnect the J2 machine harness from the ECM.
At the machine harness connector for the ECM, measure the resistance from connector contact J1-44 wire (C985-BU(Blue)) to frame ground and all of the other contacts that are used in the ECM connectors. Refer to Troubleshooting, "Wiring Harness (Short Circuit) - Test" for more information. Expected Result:Each resistance measurement is greater than 5000 ohms.Results:
YES - Each resistance measurement is greater than 5000 ohms. The circuit is correct. Proceed to Test Step 3.
NO - One or more of the resistance measurements is less than 5000 ohms. The machine harness is not correct.Repair: The machine harness has a short to a ground source. Repair the machine harness or replace the machine harness.STOPTest Step 3. Check the status of the diagnostic code
Inspect the harness connectors. Clean the contacts of the harness connectors and check the wires for damage to the insulation. Damage is caused by excessive heat, battery acid, or chafing.
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit.
Reconnect all harness connectors in order to make sure that the connectors are fully seated. Also, make sure that the clips for each connector are fastened.
Cycle the power to the machine.
Operate the machine.
Determine if the CID 0041 - FMI 04 diagnostic code is active. Expected Result:The CID 0041 - FMI 04 diagnostic code is not active.Results:
YES - The CID 0041 - FMI 04 diagnostic code is not active. The problem does not exist at this time.Repair: The initial diagnostic code was probably caused by a