COVER GP-FRONT HOUSING 1323571 - Caterpillar

Machine ECM
The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the passive (analog) circuits of the machine.
Table 1
Machine ECM (MID 71)    
DTC     Code Description     System Response    
600-3     Hydraulic Oil Temperature Sensor: Voltage above normal     Hydraulic Oil Temperature gauge on the cluster will show hot oil or blink due to error. Machines with a Demand Fan will run the fan at max while the oil temperature sensor is faulted.    
600-4     Hydraulic Oil Temperature Sensor: Voltage below normal     Hydraulic Oil Temperature gauge on the cluster will show hot oil or blink due to error. Machines with a Demand Fan will run the fan at max while the oil temperature sensor is faulted.    Possible causes for an FMI 3 diagnostic code are:
The sensor has failed.
The sensor supply or the ground circuit in the machine harness is open.
The signal circuit in the machine harness is shorted to the +battery.
The signal circuit in the machine harness is open or the sensor is disconnected.
The ECM has failed. A failure of the ECM is unlikely.Possible causes for an FMI 4 diagnostic code are:
The sensor has failed.
The signal circuit in the machine harness is shorted to ground.
The ECM has failed. A failure of the ECM is unlikely.
Illustration 1 g03469977
Schematic of the Analog Passive SensorsNote: The diagram above is a simplified schematic of the Machine ECM and the Analog Passive Sensors connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of Electrical Schematic, UENR4017 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.
Table 2
Troubleshooting Test Steps    Values    Results    
1. Identify Active FMI Code Associated With Sensor Circuit     Code present     FMI 3 diagnostic code, proceed to Test Step 2.
FMI 4 diagnostic code, proceed to Test Step 2.    
Begin Process For FMI 3 and FMI 4 Troubleshooting HERE    
2. Check The Resistance Of The Sensor
A. Turn the key start switch to OFF.
B. Disconnect the harness connectors from the sensor.
C. Check the resistance of the sensor by measuring between the positive contact and one of the negative contacts.    
The resistance of the sensor is 80 Ω to 200 Ω.     OK - The resistance measures between 80 Ω to 200 Ω.
Proceed to Test Step 3.
NOT OK- The resistance does not measure between 80 Ω to 200 Ω. The sensor has failed.
Repair - In order to confirm that the sensor is causing the problem, the harness connections can be switched. If diagnostic code has been activated, replace the sensor.
Proceed to Test Step