349F and 352F Excavators Caterpillar

Sensor Signal (Analog, Passive) - Test

Usage:

Machine ECM

The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the passive (analog) circuits of the machine.

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Table 1
Machine ECM (MID 299)
DTC	Code Description	System Response
96-4	Fuel Level Sensor: Voltage Below Normal	Fuel gauge indicator will report incorrectly.
600-4	Hydraulic Oil Temperature Sensor: Voltage Below Normal	Hydraulic Oil Temperature indicator will report incorrectly.

Possible Causes for an FMI 4 Diagnostic code are:

The sensor has failed
The signal circuit for the sensor is shorted to ground
The Machine ECM has failed. A failure of the Machine ECM is unlikely.

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Illustration 1	g03418059
Schematic of the Fuel Level Sensor and Hydraulic Oil Temperature Sensor

Note: The diagram above is a simplified schematic of the fuel level sensor, and the hydraulic oil temperature sensor connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of Electrical Schematic, UENR3640 for the complete schematic.

Diagnostic Trouble Code Procedure

Note: Prior to beginning this procedure, inspect the harness connectors that are involved in the 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 this diagnostic code is active before performing this procedure.

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Table 2
Troubleshooting Test Steps	Values	Results
1. Check The Sensor A. Turn key start switch and disconnect switch ON. B. Ensure that the diagnostic code is active. C. Disconnect sensor from machine harness.	DTC is active.	OK - Diagnostic code remains active. Proceed to Test Step 2.
2. Check The Wiring Harness Of The Sensor For A Short To Ground A. Turn the key start switch and the disconnect switch OFF. B. Disconnect machine harness connection at sensor. C. Disconnect machine harness connections at switch panel. D. At the machine harness connector for the switch panel, measure resistance from the signal contact of machine harness to all possible sources of ground. Measure resistance to all contacts of machine harness connectors for the monitor.	Each reading greater than 5K Ω.	OK - All resistance readings are greater than 5K Ω . Proceed to Test Step 3. NOT OK - One or more of the readings are less than 5 Ω. Repair: A short exists between the signal contact and the circuit with the low resistance. Repair or replace the machine harness. Note: A resistance that is greater than 5 Ω but less than 5K Ω would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit. Proceed to Test Step 3.
3. Check If The Diagnostic Code Remains A. Turn the key start switch and the disconnect switch ON. B. Clear all diagnostic codes. C. Operate the machine. D. Stop the machine and engage safety lock lever. E. Check if diagnostic code for the sensor is active.	DTC Code is no longer active.	OK - Diagnostic code does not exist at this time. Initial diagnostic code may have been caused by poor electrical connection or short at one of the harness connections. Resume machine operation. Repair: The initial diagnostic code was probably caused by a poor electrical connection or a short at one of the harness connectors. Resume normal machine operation. STOP. NOT OK - Diagnostic trouble code has not been corrected. Repair: If the diagnostic code has not been corrected after performing the procedure a second time, follow the procedure below for replacing the ECM. Prior to replacing the ECM, always contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may effect repair time. If the ECM requires replacement, see Troubleshooting, "ECM - Replace". STOP.