C7 and C9 On-Highway Engines Caterpillar

This procedure covers the following diagnostic trouble codes:

Locations of the Sensors and the Sensor Connectors

Illustration 1	g01425740
Typical left side view The crankcase pressure sensor (2) is located above the P2 connector on C9 engines. (1) Fuel rail pressure sensor (2) Crankcase pressure sensor (if equipped) on C7 engines (3) Intake manifold pressure sensor (4) Sensor connectors for sensors (13) , (14) , and (15) (5) This fuel pressure sensor for pilot fuel relates to Aftertreatment Fuel Pressure #2. (6) This fuel pressure sensor for main fuel relates to Aftertreatment Fuel Pressure #1. (7) Oil pressure sensor

Illustration 2	g01425744
Typical right side view (8) Differential pressure sensor for the combustion air supply (9) Differential pressure sensor for the clean gas induction system (10) Absolute pressure sensor for the clean gas induction system (11) Sensor connector for sensor (12) (12) Temperature sensor for the clean gas induction system (13) Flame boundary temperature sensor (Exhaust Gas Temperature 3) (14) Flame detection temperature sensor (Exhaust Gas Temperature 2) (15) Turbocharger outlet temperature sensor (Exhaust Gas Temperature 1)

Illustration 3	g01425872
Typical left side view of a C9 engine for recreational vehicles (1) Fuel rail pressure sensor (2) Crankcase pressure sensor (if equipped) (3) Intake manifold pressure sensor (4) Sensor connectors for sensors (13) , (14) , and (15) (5) This fuel pressure sensor for pilot fuel relates to Aftertreatment Fuel Pressure #2. (6) This fuel pressure sensor for main fuel relates to Aftertreatment Fuel Pressure #1. (7) Oil pressure sensor

Illustration 4	g01425890
Typical top view of the front of a C9 engine for recreational vehicles (1) Fuel rail pressure sensor (3) Intake manifold pressure sensor (9) Differential pressure sensor for the clean gas induction system (10) Differential pressure sensor for the clean gas induction system (11) Sensor connector for sensor (12) (12) Temperature sensor for the clean gas induction system

Illustration 5	g01425898
Typical view of the rear of a C9 engine for recreational vehicles The flame boundary temperature sensor is not shown. (4) Sensor connectors for sensors (13) , (14) , and (15) (8) Differential pressure sensor for the combustion air supply (14) Flame detection temperature sensor (Exhaust Gas Temperature 2) (15) Turbocharger outlet temperature sensor (Exhaust Gas Temperature 1)

Illustration 6	g01425747
Typical DPF (16) Tubing (17) Connector for the sensor group (18) Sensor group

Diagnostics on the Caterpillar Electronic Technician (ET)

Wiggle Test - The wiggle test allows you to monitor the status of the signals from the sensors while you wiggle the wiring. This helps to identify faulty electrical connections.

For additional information regarding the wiggle test, refer to the documentation that accompanies your Cat ET software.

Illustration 7	g02382419
Schematic for the active sensors

Illustration 8	g01425925
P2 ECM connector (P2-15) Intake manifold pressure (P2-16) Differential pressure for the clean gas induction system (P2-17) Return (P2-28) Oil pressure (P2-30) Return (P2-33) Crankcase pressure (P2-41) Pilot fuel pressure (P2-54) Return (P2-55) Turbocharger outlet temperature (P2-56) Inlet temperature for the DPF (P2-57) Absolute pressure for the clean gas induction system (P2-63) Flame boundary temperature (P2-66) Differential pressure for the DPF (P2-70) Temperature for the clean gas induction system (P2-72) +5 V supply (P2-80) +5 V supply (P2-81) +5 V supply (P2-82) +5 V supply (P2-83) Return (P2-85) Fuel rail pressure (P2-89) Main fuel pressure (P2-91) Flame detection temperature (P2-93) Return (P2-94) Outlet temperature for the DPF

Test Step 1. Determine if the Code is Logged or Active

Identify the diagnostic code.

Results:

• Logged -3 code or -4 code. -

  Repair: Do not troubleshoot a logged code unless the code relates to an engine symptom. If the code is logged and the code does not relate to an engine symptom, clear the code.

  If the code is logged and the code relates to an engine symptom, proceed to Test Step 2.

• Logged or active -2 code - Proceed to Test Step 7.

• Active -3 code or -4 code. - Proceed to Test Step 3.

• Logged -20 code for a thermocouple. - The temperature at the sensor briefly exceeded 1200 °C (2200 °F).

  Repair: Clear the code. No troubleshooting is required.

  STOP

• Active or logged -20 code for a sensor group for a DPF. - The tubing between the DPF and the sensor group is obstructed. Proceed to Test Step 8.

Test Step 2. Perform the Wiggle Test

Carefully following this procedure is the best way to identify the root cause of an intermittent problem.

1. Verify that the engine is OFF and that the keyswitch is ON.

2. Configure Cat ET for the wiggle test. Select the status group that includes the parameter that relates to the code. Start the wiggle test.

3. Slowly wiggle the wiring and the connectors between the P2 connector and the sensor. Pay particular attention to the wiring near each connector. Be sure to wiggle all of the wiring between the P2 connector and the sensor.

   As you wiggle the wiring, observe the wiring and the connectors. Look for these problems:

   • Loose connectors or damaged connectors

   • Moisture on the connectors or the wiring

   • Damage that is caused by excessive heat

   • Damage that is caused by chafing

   • Improper routing of wiring

   • Damaged insulation

Expected Result:

The wiring failed the wiggle test.

Results:

• The wiring failed the wiggle test. -

  Repair: Repair the wiring, when possible. Replace parts, if necessary. Verify that the problem is resolved.

  STOP

• The wiring passed the wiggle test. -

  Repair: There may be a problem inside a connector. Perform the following procedure:

  1. Disconnect the connectors for the sensor. Carefully inspect the terminals in each connector for proper installation. Each terminal must be clean and dry. Clean the terminals, if necessary.

  2. Insert a pin into each socket. Verify that each socket grips the pin firmly. Repair any problems.

  Note: Numerous diagnostic codes will become active when you disconnect the J2/P2 connectors. Ignore the additional codes and clear the codes when you are finished.

  3. Disconnect the J2/P2 connectors.

  4. Identify the P2 socket that relates to the diagnostic code. Carefully inspect the socket for proper installation. The socket must be clean and dry. Clean the socket, if necessary.

  5. Insert a pin into the socket. Verify that the socket grips the pin firmly. Repair any problems.

  6. Connect all connectors.

  7. Activate the wiggle test. Verify that the wiring passes the wiggle test.

  8. Return the engine to service.

  STOP

Test Step 3. Check the Supply Voltage at the Sensor Connector

Measure the voltage between terminal 1 (+5 V supply) and terminal 2 (Return) at the harness connector for the sensor that relates to the code.

Expected Result:

The voltage is between 4.5 VDC and 5.5 VDC.

Results:

• OK - The voltage is between 4.5 VDC and 5.5 VDC. The supply voltage is at the sensor connector. Record the voltage measurement. If you are troubleshooting a -3 diagnostic code, proceed to Test Step 4. If you are troubleshooting a -4 diagnostic code, proceed to Test Step 6.

• Not OK - The voltage is less than 4.5 VDC or the voltage is greater than 5.5 VDC.

  Repair: The voltage of the sensor supply is incorrect. Refer to Troubleshooting, "Sensor Supply - Test".

  STOP

Test Step 4. Check for Battery Voltage on the Signal Wire

Measure the voltage between the signal terminal and the return terminal on the harness connector for the sensor that relates to the diagnostic code.

Expected Result:

The voltage measurement is less than the +Battery voltage.

Results:

• Yes - The voltage measurement is less than the +Battery voltage. The signal wire is not shorted to the +Battery. Proceed to Test Step 5.

• No - The voltage measurement is approximately equal to the +Battery voltage. The signal wire is shorted to the +Battery.

  Repair: Repair the wiring, when possible. Replace parts, if necessary. Verify that the problem is resolved.

  STOP

Test Step 5. Check the Signal Wire for an Open Circuit

1. Disconnect the sensor that relates to the diagnostic code.

2. Connect a jumper wire between the signal terminal and the return terminal on the harness connector for the sensor that relates to the diagnostic code. This will replace the sensor with a short circuit.

3. Look for a -4 diagnostic code.

Expected Result:

The -3 code does not change to a -4 code when the jumper wire is connected.

Results:

• Yes - The -3 code does not change to a -4 code when the jumper wire is connected.

  Repair: There is a problem with the wiring between the sensor and the P2 connector. The most probable cause of a wiring problem is a problem with a connector. Perform the following procedure:

  1. Carefully inspect the wiring at the connector for the sensor. Pull on the wire in order to verify that the wire is crimped to the terminal and that the terminal is properly installed in the connector.

  2. Carefully inspect the wiring at the P2 connector. Pull on the wire in order to verify that the wire is crimped to the terminal and that the terminal is properly installed in the connector.

  3. Disconnect the connectors in order to verify that the wiring and terminals are installed correctly. Make the necessary repairs.

  STOP

• No - The -3 code changes to a -4 code when the jumper wire is connected. The wiring harness is OK.

  Repair: Perform the following procedure:

  1. Remove the jumper wire.

  2. Connect a new sensor to the engine harness. Do not install the sensor into the engine.

  3. Verify that the active -3 diagnostic code does not recur.

  4. Install the sensor into the engine.

  5. Clear all logged diagnostic codes and return the engine to service.

  STOP

Test Step 6. Disconnect the Sensor and Check for a -3 Diagnostic Code

1. Disconnect the sensor that applies to the -4 diagnostic code.

2. Look for a -3 diagnostic code.

3. Connect the sensor and look for a -4 diagnostic code.

Expected Result:

When the sensor is disconnected, the -4 code remains.

Results:

• Yes - When the sensor is disconnected, the -4 code remains.

  Repair: There is a problem with the wiring between the sensor and the P2 connector. The most probable cause of a wiring problem is a problem with a connector. Perform the following procedure:

  1. Carefully inspect the wiring at the connector for the sensor. Pull on the wire in order to verify that the wire is crimped to the terminal and that the terminal is properly installed in the connector.

  2. Carefully inspect the wiring at the P2 connector. Pull on the wire in order to verify that the wire is crimped to the terminal and that the terminal is properly installed in the connector.

  3. Disconnect the connectors in order to verify that the wiring and terminals are installed correctly. Make the necessary repairs.

  STOP

• No - When the sensor is disconnected, the -4 code changes to a -3 code. There is a problem with the sensor.

  Repair: Perform the following procedure:

  1. Connect a new sensor to the engine harness. Do not install the sensor into the engine.

  2. Verify that the active -4 diagnostic code does not recur.

  3. Install the sensor into the engine.

  4. Clear all logged diagnostic codes and return the engine to service.

  STOP

Test Step 7. Check the Wiring and the Sensor Group for the DPF

Show/hide table



Illustration 9	g01425971
Typical DPF (16) Tube (18) Sensor group (19) Thermocouple

1. Verify that both thermocouples (19) are threaded into the DPF.

2. Remove both tubes (16) and check the tubes for obstructions.

3. Install the tubes. Verify that all four nuts for the tubes are tight.

4. Inspect the exhaust piping between the ARD and the inlet to the DPF. Verify that the exhaust piping is free of holes and of cracks and that all clamps are securely fastened.

5. Clear the -2 code.

6. Turn the keyswitch to the OFF position.

7. Turn the keyswitch to the ON position. Wait for 15 seconds.

8. Start the engine.

9. Check for a recurrence of the -2 code.

Expected Result:

The -2 code does not return.

Results:

• Yes - The -2 code does not return. The -2 code was caused by a mechanical problem.STOP

• No - The -2 code returns. There is not a mechanical problem. There is a wiring problem.

  Repair: Perform the following procedure:

  1. Refer to Illustration 10. Disconnect the harness connector from the sensor group.

     Note: The ECM will activate a -3 code for all three sensors.

  Show/hide table
  
  

  Illustration 10	g01425978
  Harness connector for the sensor group (3) Differential pressure (4) Inlet temperature (5) Outlet temperature (6) Return

  2. Connect a jumper wire between the terminals that are listed in Table 2. Wait for a -4 code to become active.

     Note: Ensure that terminal 6 is used in your harness. If terminal 6 is not used use terminal 2 for this procedure.

     Show/hide table

     Table 2

     Code That Applies to Each Terminal on the Harness Connector for the Sensor Group
     Terminals for the Jumper Wire		Code That Should Be Activated
     Jumper wire between terminal 6 (return) and terminal 3 (differential pressure)		-4 Code for Differential Pressure
     Jumper wire between terminal 6 (return) and terminal 4 (inlet temperature)		-4 Code for Inlet Temperature
     Jumper wire between terminal 6 (return) and terminal 5 (outlet temperature)		-4 Code for Outlet Temperature

  Show/hide table
  
  

  Illustration 11	g02155333
  Sensor signal wires for the DPF

  3. If a wrong code is activated, the wiring is incorrect. Refer to Illustration 11. Check each wire from the sensor group to the ECM. Identify the wires that are crossed. Correct the wiring.

     If the correct code is activated for all three signal terminals, the wiring is OK. There is a wiring problem inside the sensor group. Replace the sensor group.

  4. Perform the following procedure in order to verify that your repair has solved the problem. Clear the codes for the sensor group.

     1. Turn the keyswitch to the OFF position.

     2. Turn the keyswitch to the ON position. Wait for 15 seconds.

     3. Start the engine. Verify that there are no -2 codes for the sensors for the DPF.

  STOP

Test Step 8. Check the Tubing Between the Sensor Group and the DPF

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Illustration 12	g01426001
Tubing on a typical DPF

1. Refer to Illustration 12. Remove the tubing from the DPF.

2. Check the tubing for obstructions. Remove any obstructions from the tubing.

3. Install the tubing. Verify that every connection is tight.

4. Clear the code. Start the engine. Allow the engine idle for 5 seconds. Stop the engine. Verify that the -20 code does not return.

Expected Result:

The -20 code does not return.

Results:

• The -20 code does not return. - STOP