ROLLER & BEARING AS 1247278 - Caterpillar

The diagnostic code is recorded when the interface module indicates that the voltage of the sensor supply circuit is too high, too low, or erratic.Possible causes of an FMI 3 Diagnostic code are:
The output of the sensor supply has shorted to the +battery circuit.
The ECM has failed. A failure of the ECM is unlikely.Possible causes of an FMI 4 Diagnostic code are:
The output of sensor supply has an open circuit.
A sensor has failed.
The ECM has failed. A failure of the ECM is unlikely.
Illustration 3 g03644274
Schematic of the Sensor Supply circuits for Implement ECM J1 connections (DTC 41 and DTC 262)
Illustration 4 g03679236
Schematic of the Sensor Supply circuits for Implement ECM J2 connections (DTC 262 and DTC 1482)
Note: The diagram above is a simplified schematic of the Implement ECM module connections. The diagram is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of: Electrical System Schematic, UENR4996, "844K Wheel Dozer (T4F) Electrical System Schematic" for the complete schematic.Electrical System Schematic, UENR1697, "844K Wheel Dozer (LRC) Electrical System Schematic"Diagnostic Trouble Code Procedure
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, listed in the table above, is active before performing this procedure.Note: Before performing this procedure, verify that all circuit breakers and all fuses in the charging circuit and the ECM system supply circuit are closed. If a problem with a circuit breaker or a fuse is found, correct the problem, and check for codes before proceeding with the following steps. Note: Poor harness connections are often the cause of a problem in electrical circuits. Before performing this procedure, inspect all of the connectors involved in the circuit. Verify that all of the connections in the circuit are dry, clean, secure, and in good condition. Each pin and socket in the connectors should mate correctly when the connectors are fastened together. Check for exposed wires at the connectors for nicks or abrasion. If a problem is found with any of the connections: correct the problem and verify that diagnostic code is still active, before performing the following procedures. For more information, refer to Troubleshooting, "Electrical Connector - Inspect".Perform a wiggle test on the sensor circuit of the machine wiring harness, using Cat ET. The wiggle test can be used to detect open or shorted connections in the machine wiring harness. Reconnect all harness connectors. Make sure that the connectors are fully seated. Observe that the clips for each connector are fastened. For more information, refer to Troubleshooting, "Electrical Connector - Inspect".
Table 3
Troubleshooting Test Steps Values Results
1. Identify The Active FMI Code Associated With The Sensor Supply Circuit
Code present. FMI 3 diagnostic code, proceed to Test Step 2.
FMI 4 diagnostic code, proceed to Test Step 4.
Begin Process For FMI 3 Troubleshooting HERE
2. Check The Voltage At The ECM
A. Turn the key start switch and the battery disconnect switch to the OFF