SEAL-U-CUP 3906823 - Caterpillar

The diagram above is a simplified schematic of the Machine ECM connections. The schematic is electrically correct. However, not all the possible harness connectors are shown.For the full Electrical Schematic of the Soil Compactors in this manual, refer to the Electrical Schematic, UENR6392.Diagnostic Trouble Code Procedure
Note: Prior to beginning this procedure, inspect the harness connectors that are involved in this circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, secure, and in good condition. If a problem with a connection is found, correct the problem and verify that the diagnostic code is active before performing a troubleshooting procedure. For sensors powered via the fuse panel, check the condition of the appropriate fuse before beginning the troubleshooting procedure.
Identify the active FMI code associated with the components.
Determine which code is present and use the list below to determine which procedure to follow.
FMI 3 diagnostic code, proceed to Table 1.
FMI 4 diagnostic code, proceed to Table 2.
Table 1
FMI 3 Troubleshooting
Troubleshooting Test Steps Values Results
1. Check The Voltage At The Sensors
A. Turn key start switch and disconnect switch ON.
B. Disconnect the machine harness connector for the sensors.
C. At the machine harness connector for the sensors, measure the voltage between the sensor supply contact and the sensor return contact.
Voltage reading is correct for the sensors. OK - The voltage reading is correct for the sensors.
Proceed to Test Step 4.
NOT OK - The voltage is greater than the supply for the circuit.
Proceed to Test Step 2.
2. Check The Power Supply At The ECM
A. Turn the key start switch and disconnect switch to the OFF position.
B. At the harness connector for the ECM, use a 151-6320 Removal Tool to remove the supply wire and the sensor return wire. The harness connector remains connected to the ECM.
C. Turn the disconnect switch and the key start switch to the ON position.
D. Use the multimeter probes to make contact on the connector pins. Measure the voltage at the ECM pins between the sensor supply contact and sensor return contact .
Voltage reading is correct for the supply. OK - The voltage is correct. The ECM power supply is correct. Install the wires and sockets that were removed from the ECM connector back into the original locations.
Proceed to Test Step 3.
NOT OK - The voltage measurement is greater than the supply voltage. The measurement is not correct. The ECM may have failed.
Proceed to Test Step 4.
3. Check For A Short In the Harness
A. The sensors remain disconnected from the machine harness.
B. The key start switch and disconnect switch remainOFF.
C. Disconnect the machine harness connectors from the ECM.
D. At the ECM harness connector, measure the resistance between the supply contact and all the other contacts that are used for the ECM.
Each resistance is greater than 5K Ω. OK - Each resistance is greater than 5K Ω.
Proceed to Test Step 4.
NOT OK - One or more readings less than 5 Ω. There is a short between