PUMP GP-ENGINE OIL 7W8599 - Caterpillar

Table 1
Transmission ECM (MID 81)    
DTC    Description    System Response    
41 - 3     8 V Supply: Voltage Above Normal     Sensors powered by the 8V supply will not function properly.    
41 - 4     8 V Supply: Voltage Below Normal     Sensors powered by the 8V supply will not function properly.    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 03 Diagnostic code are:
The output of the sensor supply has shorted to the + battery circuit.
The Implement ECM has failed. The ECM failing is unlikely.Possible causes of an FMI 04 Diagnostic code are:
The output of sensor supply has an open circuit.
A sensor has failed.
The ECM has failed. This situation is unlikely.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 Testing and Adjusting, "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 Testing and Adjusting, "Electrical Connector - Inspect".
Illustration 1 g03376649
Schematic of the 8 VDC Sensor Supply Voltage
Note: The diagrams above are a simplified schematic of the Transmission ECM connections. The diagrams are electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of the Electrical Schematic, UENR1687 for the complete schematic of 966H and 972H Wheel Loaders Electrical System. Refer to the latest revision of the Electrical Schematic, UENR1699 for the complete schematic of 980H Wheel Loaders Electrical System.
Table 2
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 3.
FMI 4 diagnostic code, proceed to Test Step 5.    
2. Check The Voltage At The ECM
A. Turn the key start switch and the battery disconnect switch to the