COOLER GP-FLTR BASE & ENG OIL 1957606 - Caterpillar

Possible causes for an FMI 3 Diagnostic code are:
The power supply circuit for the sensor is open.
The return circuit is open.
The signal circuit is open or the sensor is disconnected.
The signal circuit is shorted to the sensor power supply.
The sensor has failed.
The sensor was activated in Cat ET when the component is not on the machine.
The ECM has failed. An ECM failure is unlikely.Possible causes for an FMI 4 Diagnostic code are:
The signal circuit for the sensor is shorted to ground.
The sensor has failed.
The ECM has failed. An ECM failure is unlikely.
Illustration 2 g03642897
Schematic of the Analog Active circuits
Note: The diagram above is a simplified schematic of the connections for the sensor signal (analog active) circuits. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of the Electrical Schematic, UENR3117 for the complete schematic.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.
Table 3
Troubleshooting Test Steps Values Results
1. Identify Active DTC Code Associated With Sensor Circuit
Code present. FMI 3 diagnostic code, proceed to Test Step 2.
FMI 4 diagnostic code, proceed to Test Step 6.
Begin Process For FMI 3 Troubleshooting HERE
2. Check The Supply Voltage at the Sensor
A. Turn key start switch and disconnect switch ON.
B. Disconnect the machine harness from sensor.
C. Refer to the schematic to determine the voltage source for the suspected faulty sensor.
D. Measure voltage between supply and return contacts at the machine harness connector for the sensor.
Voltage is 8.0 0.5 VDC or 5.0 0.5 VDC OK - The voltage reading is correct for the suspected faulty sensor.
Proceed to Test Step 3.
NOT OK- The voltage is NOT correct for the circuit.
Repair: If there is an active CID 263 (Digital Sensor Power Supply 8 VDC Or 12 VDC) or CID 262 (5 V Sensor DC Power Supply) troubleshoot the code.
If there is not an active CID 263 or 262 replace the circuit breaker associated with the sensor.
Proceed to Test Step 7.
3. Check For An Open In The Sensor Circuit
A. The sensor remains disconnected from the machine harness.
B. Turn the key start switch and the disconnect switch OFF.
C. At the harness connector for the sensor, place a jumper wire between the signal contact and frame ground.
D. Disconnect J1 and J2 harness connectors from the ECM.
E. At the machine harness connector for the ECM, measure the resistance from the signal contact for the sensor to frame ground.
F. Gently pull on the wire and move the wire in a circular motion at the ECM connector and observe the