BUSHING-MASTER 4860750 - Caterpillar

Illustration 2 g03350500
Schematic of the passive sensors for the model 621K, 623K, and 627K tractor/scraper machines associated with the Scraper Transmission ECM.
Illustration 3 g03318441
Schematic of the passive sensors for the model 621K, 623K, and 627K tractor/scraper machines associated with the Transmission/Chassis ECM.
Note: The illustrations above are simplified schematics of the ECM connections. The schematics are electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of the Electrical Schematic for your specific machine. Refer to the list below to identify the correct schematic for your machine.
Electrical Schematic, UENR2689 for the 621K Tractor/Scraper.
Electrical Schematic, UENR2690 for the 623K Tractor/Scraper.
Electrical Schematic, UENR2691 for the 627K Tractor/Scraper.Diagnostic Trouble Code Procedure
Note: Poor harness connections are often the cause of a problem in electrical circuits. Before performing any troubleshooting 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".
Table 5
Troubleshooting Test Steps Values Results
1. Identify The Active DTC Code Associated With The Suspect Circuit.
Code present. FMI 3 diagnostic code, proceed to Test Step 2.
FMI 4 diagnostic code, proceed to Test Step 5.
Begin Process For FMI 3 Troubleshooting HERE
2. Check For Voltage At The Sensor.
A. Turn the key start switch and the disconnect switch to the ON position.
B. Disconnect the sensor from the machine harness.
C. At the machine harness connector for the sensor, measure the voltage between contact 1 and 2.
The voltage should measure 5 0.3 VDC. OK - The voltage is 5 0.3 VDC.
Proceed to Test Step 3.
NOT OK - The voltage is not within the tolerance expected at 5 VDC.
Repair- There is a problem with the machine harness or the ECM has failed. A failure of the ECM is unlikely.
Proceed to Test Step 4.
3. Check For An Open In The Sensor Circuit.
A. Turn the key start switch and disconnect switch to the OFF position.
B. Disconnect the J1 and J2 machine harness connectors from the ECM.
C. At the machine harness connector for the sensor, install a jumper wire from contact 1 to contact 2.
D. At the harness connector for the sensor, measure the resistance from the signal contact to all possible connections of the negative battery. .Refer to the electrical schematic for your machine for more information about the circuits. (See above.)
E. At the harness connector for the ECM measure the resistance at the contacts for the sensor.
The resistance reading is less than 5 Ω. OK - The resistance is less than 5 Ω.
Proceed to Test Step 4.
NOT OK - The resistance is greater than 5K Ω. There is an open in the machine harness somewhere between the