G3516C, G3516E, and G3512E Generator Set Engines Caterpillar

Use this procedure to troubleshoot diagnostic codes for open circuits or short circuits for the circuits of these parameters:

• Filtered engine oil pressure

• Air inlet pressure

• Intake manifold air temperature

• Engine oil temperature

• Unfiltered engine oil pressure

• Fuel quality

• Compressor discharge pressure

This procedure covers the following diagnostic codes:

• 100-3 Engine Oil Pressure Sensor : Voltage Above Normal

• 100-4 Engine Oil Pressure Sensor : Voltage Below Normal

• 102-3 Boost Pressure Sensor : Voltage Above Normal

• 102-8 Boost Pressure Sensor : Abnormal Frequency, Pulse Width, or Period

• 100-4 Engine Oil Pressure Sensor : Voltage Below Normal

• 106-3 Air Inlet Pressure Sensor : Voltage Above Normal

• 106-4 Air Inlet Pressure Sensor : Voltage Below Normal

• 172-3 Intake Manifold Air Temperature Sensor : Voltage Above Normal

• 172-4 Intake Manifold Air Temperature Sensor : Voltage Below Normal

• 175-3 Engine Oil Temperature Sensor : Voltage Above Normal

• 175-4 Engine Oil Temperature Sensor : Voltage Below Normal

• 542-3 Engine Oil Pressure Sensor - Before Oil Filter : Voltage Above Normal

• 542-4 Engine Oil Pressure Sensor - Before Oil Filter : Voltage Below Normal

• 2449-5 Fuel Quality Sensor : Current Below Normal

• 2449-6 Fuel Quality Sensor : Current Above Normal

• 2852-3 Compressor Discharge Pressure Sensor : Voltage Above Normal

• 2852-4 Compressor Discharge Pressure Sensor : Voltage Below Normal

Note: The air inlet pressure sensor may be a PWM sensor or an analog sensor. Determine the type of sensor before you use this procedure. The air inlet pressure sensor is a PWM sensor if a wire is installed in P1-10. Refer to Troubleshooting, "Sensor Signal (PWM) - Test" if the air inlet pressure sensor is a PWM sensor. The air inlet pressure sensor is an analog sensor if a wire is installed in terminal P1-15 or P5-15.

A -3 code is probably caused by a problem in an engine harness. There may be an open circuit in a harness, or a short circuit to a positive voltage source in a harness. The next likely cause is a sensor problem. The least likely cause is a problem with a control module.

A -4 code is probably caused by a short circuit to ground in an engine harness. The next likely cause is a sensor problem. The least likely cause is a problem with a control module.

Logged diagnostic codes provide a historical record. Before you begin this procedure, use Caterpillar Electronic Technician (ET) to print the logged codes to a file.

This troubleshooting procedure may generate additional diagnostic codes. Keep your mind on correcting the cause of the original diagnostic code. Clear the diagnostic code after the problem is resolved.

Illustration 1	g01325334
Schematic for the active analog inputs

Test Step 1. Inspect the Electrical Connectors and Wiring

1. Remove the electrical power from the engine.

   Note: For the following steps, refer to Troubleshooting, "Electrical Connectors - Inspect".

2. Thoroughly inspect each of the following connectors:

   • J1/P1 connectors

   • J5/P5 connectors

   • J6/P6 connectors

   • J7/P7 connectors

   • J9/P9 connectors

   1. Check the torque of the allen head screws on the Electronic Control Module (ECM).

   2. If you are troubleshooting a problem with an analog sensor, perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit for the analog sensors.

   3. If you are troubleshooting a problem with an analog sensor, check the harness and wiring for abrasion and for pinch points from the analog sensors to the ECM.

   4. If you are troubleshooting a problem with the input for fuel quality, perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit for the fuel quality.

   5. If you are troubleshooting a problem with the input for fuel quality, check the harness and wiring for abrasion and for pinch points from the gas chromatograph to the ECM.

Expected Result:

All connectors, pins, and sockets are connected properly. The connectors and the wiring do not have corrosion, abrasion, or pinch points.

Results:

• OK - All connectors, pins, and sockets are connected properly. The connectors and the wiring do not have corrosion, abrasion, or pinch points. The components are in good condition with proper connections. If you are troubleshooting a problem with an analog sensor, proceed to Test Step 2. If you are troubleshooting a 2449-5 code, proceed to Test Step 9. If you are troubleshooting a 2449-6 code, proceed to Test Step 12. If you are troubleshooting a 102-8 code, proceed to Test Step 4.

• Not OK - At least one of the connectors, pins, and/or sockets are not connected properly. At least one of the connectors and/or the wiring has corrosion, abrasion, or pinch points.

  Repair: Perform the necessary repairs and/or replace parts, if necessary.

  STOP

Test Step 2. Check for Diagnostic Codes for the Power Supply

1. Connect Cat ET to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".

2. Observe the "Active Diagnostic" screen on ET. Allow a minimum of 30 seconds for any codes to activate. Look for these codes:

   • 262-3

   • 262-4

Expected Result:

The 262-3 code or the 262-4 code is not active.

Results:

• No codes - There are no diagnostic codes for the sensor supply. If you are troubleshooting a -3 code, proceed to Test Step 4. If you are troubleshooting a -4 code or a -8 code, proceed to Test Step 3.

• Active code - There is an active diagnostic code for the sensor supply. This procedure will not work when this type of code is active.

  Repair: Refer to Troubleshooting, "Sensor Supply - Test".

  If necessary, return to this functional test in order to troubleshoot the analog input after the diagnostic code for the sensor supply has been resolved.

  STOP

Test Step 3. Create an Open Circuit for the Sensor

1. Disconnect the sensor that has the "voltage below normal" diagnostic code.

2. Observe the "Active Diagnostic" screen on Cat ET. Allow a minimum of 30 seconds for any codes to activate. Look for an active -3 diagnostic code.

Expected Result:

There is an active -3 diagnostic code for the disconnected sensor.

Results:

• Yes - Before the suspect sensor was disconnected, there was an active -4 diagnostic code or an active -8 diagnostic code for the sensor. After the suspect sensor was disconnected, there was an active -3 diagnostic code for the sensor.

  Repair: Connect the sensor. If the active -4 diagnostic code or the active -8 diagnostic code recurs, replace the original sensor.

  Verify that the code does not activate when the new sensor is installed. Clear the logged codes from the ECM.

  STOP

• No - Before the suspect sensor was disconnected, there was an active -4 diagnostic code or an active -8 diagnostic code for the sensor. After the suspect sensor was disconnected, the active -4 diagnostic code or the active -8 diagnostic code remained. Proceed to Test Step 4.

Test Step 4. Check the Supply Voltage at the Sensor Connector

1. Verify that the suspect sensor is disconnected from the engine harness.
   Show/hide table

   Illustration 2	g00889729
   Harness connectors for the various sensors (A) 5 volt supply (B) Return (C) Signal

2. At the harness connector for the suspect sensor, measure the voltage between terminals (A) and (B).

Expected Result:

The voltage is between 4.5 VDC and 5.5 VDC.

Results:

• OK - The voltage between terminals A and B is between 4.5 VDC and 5.5 VDC. The 5 volt supply is present at the sensor connector. Proceed to Test Step 5.

• Not OK - The voltage between terminals A and terminal B is not between 4.5 VDC and 5.5 VDC. The 5 volt supply is not present at the sensor connector. The 5 volts must be present at the sensor in order to continue this procedure.

  Repair: Verify that the wiring and/or connectors are OK. Repair any faulty wiring and/or connectors, when possible. Replace parts, if necessary.

  STOP

Test Step 5. Check the Pull-Up Voltage at the Sensor

1. Verify that the suspect sensor's connector is disconnected from the engine harness.
   Show/hide table

   Illustration 3	g01303723
   Harness connectors for the various sensors (A) 5 volt supply (B) Return (C) Signal

2. At the harness connector for the suspect sensor, measure the voltage between terminals (B) and (C).

Expected Result:

The voltage is between 6.0 VDC and 7.0 VDC.

Results:

• OK - The voltage between the signal terminal and the return terminal is between 6.0 VDC and 7.0 VDC. The pull-up voltage that is created by the ECM is present at the sensor connector. The signal wire and the return wire for the suspect sensor appear to be OK. Proceed to Test Step 7.

• Not OK - The voltage between the signal terminal and the return terminal is not between 6.0 VDC and 7.0 VDC. The pull-up voltage that is created by the ECM is not present at the sensor connector. Proceed to Test Step 6.

Test Step 6. Check the Pull-Up Voltage at the ECM

1. Use a 151-6320 Wire Removal Tool to remove the signal wire for the suspect sensor from the appropriate ECM connector.

2. Use a jumper wire with Deutsch terminals on the ends. Insert one end of the jumper wire into the open terminal of the P1 connector or P5 connector.

3. Connect a multimeter lead to the end of the jumper wire that is not inserted into the connector.

4. At the harness side of the P1 connector or P5 connector, insert a 7X-1710 Multimeter Probe along terminal 3.

5. Connect the other multimeter lead to the probe.

6. Measure the sensor's pull-up voltage.

Expected Result:

The pull-up voltage is between 6.0 VDC and 7.0 VDC.

Results:

• OK - The pull-up voltage for the suspect sensor is between 6.0 VDC and 7.0 VDC. The ECM is producing a pull-up voltage that is valid. There is a problem with the signal wire between the module's connector and the harness connector for the sensor. There may be a problem with a connector.

  Repair: Perform the following procedure:

  Disconnect the multimeter leads.

  Use a 151-6320 Wire Removal Tool to remove the jumper wire from the module's connector.

  Install the terminal that was removed from the module's connector. Pull on the wire in order to verify proper installation of the terminal.

  Verify that the wiring and/or connectors are OK. Repair any faulty wiring and/or connectors, when possible. Replace any wiring and/or connectors, if necessary.

  STOP

• Not OK - The sensor's pull-up voltage at the module is not between 6.0 VDC and 7.0 VDC. Proceed to Test Step 8.

Test Step 7. Check the Sensor

1. Temporarily connect a sensor that is known to be good to the engine harness.

2. Observe the "Active Diagnostic" screen on Cat ET. Allow a minimum of 30 seconds for any codes to activate.

Expected Result:

No diagnostic codes are activated.

Results:

• OK - No diagnostic codes are activated when a good sensor is installed. Connecting a new sensor resolved the problem.

  Repair: Replace the faulty sensor with the new sensor. For the proper torque value for the new sensor, refer to the Specifications manual.

  STOP

• Not OK - An active code remains. Connecting a new sensor did not resolve the problem. Proceed to Test Step 8.

Test Step 8. Check the Operation of the Module

1. Verify that the signal wire for the suspect sensor has been removed from the module's connector.

2. Clear any existing diagnostic codes.

3. Observe the "Active Diagnostic" screen on ET. Allow a minimum of 30 seconds for any codes to activate.

   An active -3 diagnostic code is generated for the sensor.

4. Use a jumper wire that is the appropriate length with Deutsch terminals on the ends. Install one end of the jumper wire into the terminal for the signal wire that was removed from the module's connector. Install the other end of the jumper wire into terminal P1-19. This will replace the sensor circuit with a short circuit.

5. Observe the "Active Diagnostic" screen on Cat ET. Allow a minimum of 30 seconds for any codes to activate.

   An active -4 diagnostic code or an active -8 diagnostic code is generated.

Expected Result:

Active -3, -4, or -8 diagnostic codes are generated according to the above steps.

Results:

• OK - Active -3, -4, or -8 diagnostic codes are generated according to the above steps. The module is operating correctly. The initial diagnostic code was probably caused by a poor electrical connection.

  Repair: Perform the following procedure:

  Use a 151-6320 Wire Removal Tool to remove the jumper wire from the module's connector.

  Install the terminal that was removed from the module's connector. Pull on the wire in order to verify proper installation of the terminal.

  Resume normal operation.

  STOP

• Not OK - No active -3, -4, or -8 diagnostic codes were generated. The ECM is not operating correctly.

  Repair: Temporarily install a new module. Refer to Troubleshooting, "ECM - Replace".

  If the problem is resolved with the new module, install the original module and verify that the problem returns. If the new module operates correctly and the original module does not operate correctly, replace the module. Refer to Troubleshooting, "ECM - Replace".

  STOP

Test Step 9. Check for an Open Circuit

1. Remove the two wires (+ and −) for the 4 to 20 mA signal from the device that supplies the 4 to 20 mA signal.

2. Install a jumper wire between the two wires (+ and −) that were removed from the device that supplies the 4 to 20 mA signal.

3. Disconnect the P1 connector.

4. Measure the resistance between terminals P1-38 and P1-39.

Expected Result:

The resistance is less than five Ohms.

Results:

• OK - The resistance is less than five Ohms. The circuit is not open.

  Repair: Remove the jumper wire. Insulate the wire leads with electrical tape in order to ensure that the leads do not create a short circuit.

  Proceed to Test Step 10.

• Not OK - The resistance is greater than 5 Ohms. There is a problem with a connector and/or the wiring.

  Repair: Repair the connection and/or the wire, when possible. Replace parts, if necessary. Verify that the problem is resolved.

  STOP

Test Step 10. Check for a Short Circuit to the +Battery at Terminal P1-38

1. Make sure that there is no electrical power to the device that provides the 4 to 20 mA signal.

2. Measure the resistance between terminals P1-38 and P1-57.

Expected Result:

The resistance is greater than five Ohms.

Results:

• Yes - The resistance is greater than five Ohms. The wiring from terminal P1-38 is not shorted to the +Battery side. Do not connect any connectors. Proceed to Test Step 11.

• No - The resistance is less than five Ohms.

  Repair: Repair the connection and/or the wire, when possible. Replace parts, if necessary. Verify that the problem is resolved.

  STOP

Test Step 11. Check for a Short to Ground at Terminal P1-39

1. Make sure that the leads of the wires for the 4 to 20 mA signal do not create a short circuit.

2. Measure the resistance between the ground strap for the ECM and terminal P1-39.

Expected Result:

The resistance is greater than five Ohms.

Results:

• Yes - The resistance is greater than five Ohms. The wiring from terminal P1-39 appears to be OK.

  Repair: Connect the P1 connector. Connect the two wires ("+" and "-") for the 4 to 20 mA signal to the device that supplies the 4 to 20 mA signal.

  Proceed to Test Step 14.

• No - The resistance is less than five Ohms. There is a problem with a connection and/or the wiring that is connected to P1-39.

  Repair: Locate the wire with the short circuit and replace the wire. Verify that the problem is resolved.

  STOP

Test Step 12. Check for a Short Circuit to the +Battery Side at Terminal P1-39

1. Make sure that there is no electrical power to the device that provides the 4 to 20 mA signal.

2. Remove the two wires ("+" and "-") for the 4 to 20 mA signal from the device that supplies the 4 to 20 mA signal. Insulate the wire leads with electrical tape in order to ensure that the leads do not create a short circuit.

3. Disconnect the P1 connector.

4. Measure the resistance between terminals P1-39 and P1-57.

Expected Result:

The resistance is greater than five Ohms.

Results:

• Yes - The resistance is greater than five Ohms. The wiring from terminal P1-39 is not shorted to the +Battery side. Do not connect any connectors. Proceed to Test Step 13.

• No - The resistance is less than five Ohms. There is a problem with a connection and/or the wiring from terminal P1-39.

  Repair: Repair the connection and/or the wire, when possible. Replace parts, if necessary. Verify that the problem is resolved.

  STOP

Test Step 13. Check for a Short Circuit to Ground at Terminal P1-38

1. Make sure that the ends of the wires for the 4 to 20 mA signal do not create a short circuit.

2. Measure the resistance between the ground strap for the ECM and terminal P1-38.

Expected Result:

The resistance is greater than five Ohms.

Results:

• Yes - The resistance is greater than five Ohms. The wiring from terminal P1-38 appears to be OK. Do not connect any connectors. Proceed to Test Step 14.

• No - The resistance is less than five Ohms. There is a problem with a connection and/or the wiring from terminal P1-38.

  Repair: Repair the connection and/or the wire, when possible. Replace parts, if necessary. Verify that the problem is resolved.

  STOP

Test Step 14. Check the Device that Provides the 4 to 20 mA Signal

Measure the 4 to 20 mA signal according to the literature that is provided by the OEM. Verify that the correct signal is provided to the ECM.

Verify the correct 4 to 20 mA signal at terminals P1-38 and P1-39.

Expected Result:

The correct 4 to 20 mA signal is provided to the ECM.

Results:

• Yes - The correct 4 to 20 mA signal is provided to the ECM. However, the ECM is not responding correctly to the signal. There may be a problem with the ECM.

  Repair: Replace the ECM according to Troubleshooting, "ECM - Replace". Verify that the problem is resolved.

  STOP

• No - The ECM is not receiving the correct 4 to 20 mA signal. There is probably a problem with the device that provides the 4 to 20 mA.

  Repair: Service the device that provides the 4 to 20 mA according to the literature that is provided by the OEM of the device. Verify that the problem is resolved.

  STOP