320D3 GC Excavators Machine Electronic Control System Sensor Signal (Analog, Active) - Test Caterpillar


Sensor Signal (Analog, Active) - Test
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1.1. Machine ECM
2.1. Diagnostic Trouble Code Procedure
3.1. FMI 3
4.1. FMI 4

Machine ECM

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

Table 1
Machine ECM (MID 299) 
J1939  CDL  Code Description  System Response 
  100-3  Engine Oil Pressure Sensor : Voltage Above Normal  Oil pressure sensor will read incorrectly. Engine may not operate as requested. 
  100-4  Engine Oil Pressure Sensor : Voltage Below Normal  Oil pressure sensor will read incorrectly. Engine may not operate as requested. 
  3528-3  Barometric Pressure Sensor : Voltage Above Normal  Engine may not operate as requested. 
  3528-4  Barometric Pressure Sensor : Voltage Below Normal  Engine may not operate as requested. 


Illustration 1g06575524
Sensor Signal (Analog, Active) schematic

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. Refer to the latest revision of Electrical Schematic, M0116913 for 320D3 GC excavator electrical systems.

Diagnostic Trouble Code Procedure

Table 2
Required Tools 
Tool  Part Number  Description  Qty 
T1  146-4080(1)  Digital Multimeter Group 
8T-3224 Needle Tip Group 
7X-1710 Multimeter Probe Group 
8T-8726 Cable Assembly (Three Pin) (3-Pin Breakout) 
T2  JERD2129  Cat® Electronic Technician (Cat ET) 
Windows-based PC 
538-5051 Communication Adapter Gp 
T3  6V-4148  Connector Repair Kit (Sure Seal) 
T4  190-8900  Connector Field Repair Kit (Deutsch) 
T5  175-3700  Connector Repair Kit Deutsch DT 
(1) This multimeter can use an RS232C cable to connect to a Laptop computer or Dataview tool gp for troubleshooting.

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.

  1. Identify the active FMI code associated with the faulty component.

  2. Determine which code is present and use the list below to determine the correct procedure to follow.

    • FMI 3 diagnostic code, proceed to "FMI 3".

    • FMI 4 diagnostic code, proceed to "FMI 4".

FMI 3

Table 3
Check The Voltage At The Sensor 
Troubleshooting Test Steps  Values  Results 
1. Turn key start switch and disconnect switch ON.

2. Refer to the schematic to determine the voltage source for the sensor.

3. At the machine harness connector for the sensor, insert 7X-1710 multimeter probes along the sensor supply and sensor return.

4. At the sensor harness connector, measure voltage between the sensor supply and sensor return. 
Voltage reading is correct for the sensor.  Result: The voltage reading is correct for the sensor.

Proceed to "Check The Harness For An Open" Table 4.

Result: The voltage is not correct for the circuit.

Proceed to "Check The Harness For An Open" Table 4. 

Table 4
Check The Harness For An Open 
Troubleshooting Test Steps  Values  Results 
1. The key start switch and the disconnect switch remain in the OFF position.

2. Disconnect the machine harness connector from the sensor.

3. At the sensor harness connector, install a jumper wire between the sensor return contact and signal contact.

4. Turn the key switch and disconnect switch ON.

5. Observe the status of the diagnostic code. 
The diagnostic code changes from an FMI 3 to an FMI 4.  Result: The diagnostic code changes from an FMI 3 to an FMI 4. The sensor has failed.

Repair: Replace the sensor.

Proceed to "Check If The Diagnostic Code Remains" Table 6.

Result: The diagnostic code does not change from an FMI 3 to an FMI 4.

Proceed to "Check Signal Circuit For A Short To +Battery" Table 5. 

Table 5
Check Signal Circuit For A Short To +Battery 
Troubleshooting Test Steps  Values  Results 
1. Turn the key start switch and the disconnect switch to the OFF position.

2. Disconnect the ECM harness connectors. The sensor harness connector remains disconnected.

3. Remove the jumper wire that was installed in the previous test step.

4. At the ECM harness connector, measure the resistance between the signal contact and all other +battery circuits used in the ECM harness connectors. 
Each resistance is greater than 5K Ω.  Result: Each resistance is greater than 5K Ω. The harness circuit is correct.

Proceed to "Check If The Diagnostic Code Remains" Table 6.

Result: The resistance is less than 5 Ω. A short exists in the harness between the signal circuit and the circuit with the low-resistance measurement.

Repair: 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 "Check If The Diagnostic Code Remains" Table 6. 

Table 6
Check If The Diagnostic Code Remains 
Troubleshooting Test Steps  Values  Results 
1. Reconnect all harness connectors. Return machine to normal operating condition.

2. Turn the key start switch and the disconnect switch ON.

3. Clear all diagnostic codes.

4. Operate the machine.

5. Stop the machine and engage the safety lock.

6. Check if the diagnostic code is active. 
The diagnostic code is no longer present.  Result: The diagnostic code does not exist currently. The initial diagnostic code may have been caused by poor electrical connection or short at one of the harness connections. Resume machine operation.

STOP.

Result: The diagnostic trouble code has not been corrected. If the diagnostic code has not been corrected after performing the procedure a second time, the ECM may require replacement.

Prior to replacing the ECM, always contact the Technical Communicator at your dealership for possible consultation with AVSpare. This consultation may effect repair time.

Follow the steps in Troubleshooting, "ECM - Replace" if the ECM needs to be replaced.

STOP. 

FMI 4

Table 7
Check The Sensor 
Troubleshooting Test Steps  Values  Results 
1. Turn the disconnect switch and the key start switch ON.

2. Disconnect the sensor from the machine harness.

3. Observe the status of the diagnostic code as the sensor is disconnected from the harness. 
The code changes from an FMI 4 to an FMI 3 when the sensor is disconnected.  Result: The code changes from an FMI 4 to an FMI 3 when the sensor is disconnected. The sensor has failed.

Repair: Replace the sensor.

Proceed to "Check If The Diagnostic Code Remains" Table 9.

Result: The FMI 4 diagnostic code remains active when sensor is disconnected. The sensor is not the cause of the problem.

Proceed to "Check The Signal Circuit For A Short To Ground" Table 8. 

Table 8
Check The Signal Circuit For A Short To Ground 
Troubleshooting Test Steps  Values  Results 
1. Turn the key start switch and the disconnect switch OFF.

2. Disconnect the harness connectors from the ECM.

3. At the ECM harness connector, measure the resistance between the sensor signal contact and all other contacts used in the ECM harness connectors. 
The resistance is greater than 5K Ω.  Result: The resistance is greater than 5K Ω. The harness circuit is correct.

Proceed to "Check If The Diagnostic Code Remains" Table 9.

Result: The resistance is less than 5 Ω. A short circuit exists between the signal circuit and the circuit with the low-resistance measurement.

Repair: 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 "Check If The Diagnostic Code Remains" Table 9. 

Table 9
Check If The Diagnostic Code Remains 
Troubleshooting Test Steps  Values  Results 
1. Reconnect all harness connectors. Return machine to normal operating condition.

2. Turn the key start switch and the disconnect switch ON.

3. Clear all diagnostic codes.

4. Operate the machine.

5. Stop the machine and engage the safety lock.

6. Check if the diagnostic code is active. 
The diagnostic code is no longer present.  Result: The diagnostic code does not exist currently. The initial diagnostic code may have been caused by a poor electrical connection or short at one of the harness connections. Resume machine operation.

STOP.

Result: The diagnostic trouble code has not been corrected. If the diagnostic code has not been corrected after performing the procedure a second time, the ECM may require replacement.

Prior to replacing the ECM, always contact the Technical Communicator at your dealership for possible consultation with AVSpare. This consultation may effect repair time.

Follow the steps in Troubleshooting, "ECM - Replace" if the ECM needs to be replaced.

STOP. 

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