C4.4 and C6.6 Industrial Engines and Engines for Caterpillar Built Machines Caterpillar

Use this procedure under the following conditions:

This procedure covers open circuit diagnostic codes and short circuit diagnostic codes that are associated with the following sensors:

• Coolant temperature sensor

• Intake manifold air temperature sensor

Use this procedure to troubleshoot the system when one of the following diagnostic codes is an active diagnostic code or a recently logged diagnostic code or when a diagnostic code can easily be activated.

• 0110-03 Engine Coolant Temperature Sensor voltage above normal

• 0110-04 Engine Coolant Temperature Sensor voltage below normal

• 0172-03 Intake Manifold Air Temperature Sensor voltage above normal

• 0172-04 Intake Manifold Air Temperature Sensor voltage below normal

The following background information is related to this procedure:

The troubleshooting procedures for the diagnostic codes of each temperature sensor are identical. The temperature sensors have two terminals. Pin P2:37 is the common connection for the engine temperature sensors. The sensor common connection is shared between the temperature sensors. The common line is connected to each sensor connector terminal 2. Terminal 1 is the sensor output. The signal voltage from terminal 1 of each sensor is supplied to the appropriate terminal in the P2/J2 connector.

Pull-up Voltage

The ECM continuously outputs a pull-up voltage on the circuit for the sensor signal wire. The ECM uses this pull-up voltage in order to detect an open in the signal circuit. When the ECM detects the presence of a voltage that is above a threshold on the signal circuit, the ECM will generate an open circuit diagnostic code (3) for the sensor.

If the sensor is disconnected at the sensor connector, the presence of pull-up voltage at the sensor connector indicates that the wires from the sensor connector to the ECM are not open or shorted to ground. If the sensor is disconnected at the sensor connector, the absence of pull-up voltage at the sensor connector indicates an open in the signal wire or a short to ground. If the sensor is disconnected at the sensor connector and the voltage at the sensor connector is different from pull-up voltage, the signal wire is shorted to another wire in the harness.

The troubleshooting procedures for the diagnostic codes of each temperature sensor are identical. The temperature sensors are passive sensors. The temperature sensor has two terminals. The common line is connected to each sensor connector terminal 2. The signal voltage from terminal 1 of each sensor is supplied to the appropriate terminal at the P2/J2 ECM connector.

Illustration 1	g01803534
Schematic for engine temperature sensors

Illustration 2	g01803535
Typical view of the P2 pin locations for the temperature sensors (37) Ground (GND) Intake Manifold Air Temperature Sensor and Coolant Temperature Sensor (42) Signal (SIG) Intake Manifold Air Temperature Sensor (43) Signal (SIG) Coolant Temperature Sensor

Illustration 3	g01170313
Engine coolant temperature sensor and intake manifold air temperature sensor (1) Signal (SIG) (2) Ground (GND)

Test Step 1. Verify All Active Diagnostic Codes

1. Connect the electronic service tool to the diagnostic connector.

2. Turn the keyswitch to the ON position.

   Note: Wait at least 30 seconds for activation of the diagnostic codes.

3. Use the electronic service tool in order to verify if any of the following diagnostic codes are active or recently logged:
   • 0110-03 Engine Coolant Temperature Sensor voltage above normal

   • 0110-04 Engine Coolant Temperature Sensor voltage below normal

   • 0172-03 Intake Manifold Air Temperature Sensor voltage above normal

   • 0172-04 Intake Manifold Air Temperature Sensor voltage below normal

Expected Result:

One or more of the preceding diagnostic codes are active or recently logged.

Results:

• Yes - Proceed to Test Step 2.

• No - The fault is intermittent. Proceed to Test Step 8.

Test Step 2. Inspect Electrical Connectors And Wiring

1. Thoroughly inspect the P2 connector and the suspect sensor connector. Refer to Troubleshooting, "Electrical Connectors - Inspect".

2. Perform a 45 N (10 lb) pull test on each of the wires in the sensor connector and the ECM connector that are associated with the active diagnostic code.

   Refer to illustration 2.

3. Verify that the latch tab of the connector is correctly latched. Also verify that the latch tab of the connector has returned to the fully latching position.

4. Check the screw for the ECM connector for the correct torque of 5.0 N·m (44 lb in).

5. Check the harness for abrasions and for pinch points from the sensor to the ECM.

Expected Result:

All connectors, pins, and sockets should be completely coupled and/or inserted. The harness should be free of corrosion, abrasion, and pinch points.

Results:

• OK - Proceed to Test Step 3.

• Not OK - Repair the connectors or the harness and/or replace the connectors or the harness. Ensure that all of the seals are correctly in place and ensure that the connectors are completely coupled. Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair has eliminated the fault. If the fault has not been eliminated, proceed to Test Step 3.

Test Step 3. Verify That The Diagnostic Code Is Still Active

1. Turn the keyswitch to the ON position.

   Note: Wait at least 10 seconds for activation of the diagnostic codes.

2. Access the "Active Diagnostic Code" screen on the electronic service tool and check for active diagnostic codes.

3. Determine if the fault is related to a Voltage Above Normal diagnostic code or a Voltage Below Normal diagnostic code.

Expected Result:

A Voltage Below Normal diagnostic code or an Voltage Above Normal diagnostic code is active.

Results:

• OK - SHORT Circuit - A Voltage Below Normal diagnostic code is active at this time. Proceed to Test Step 4.

• OK - OPEN Circuit - An Voltage Above Normal diagnostic code is active at this time. Proceed to Test Step 5.

• Not OK - A Voltage Below Normal diagnostic code is not active. A Voltage Above Normal diagnostic code is not active. An intermittent fault may exist.

  Repair: Use the electronic service tool to perform a "Wiggle Test". If faults are indicated, then go to the appropriate procedure.

  STOP

Test Step 4. Disconnect The Sensor In Order To Create An Open Circuit

1. Turn the keyswitch to the OFF position.

2. Disconnect the sensor connector of the sensor with the Voltage Below Normal diagnostic code.

3. Turn the keyswitch to the ON position.

   Note: Wait at least 10 seconds for activation of the diagnostic codes.

4. Access the "Active Diagnostic Code" screen of the electronic service tool. Check for an active Voltage Above Normal diagnostic code.

Expected Result:

A Voltage Above Normal diagnostic code for the disconnected sensor is now active.

Results:

• OK - A Voltage Below Normal diagnostic code was active before disconnecting the sensor. A Voltage Above Normal diagnostic code became active after disconnecting the sensor.

  Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect".Inspect the seals of the connectors for damage.Connect the sensor and verify that the fault returns. If the fault returns, the sensor is faulty.Replace the sensor.Use the electronic service tool in order to clear all logged diagnostic codes.

  STOP

• Not OK - A Voltage Below Normal diagnostic code was active before disconnecting the sensor. The Voltage Below Normal diagnostic code is still active after disconnecting the sensor. There is a short circuit between the sensor harness connector and the ECM. Leave the sensor disconnected. Proceed to Test Step 6.

Test Step 5. Create a Short Circuit Between the Signal and the Common Terminals at the Sensor Harness Connector

1. Disconnect the suspect sensor connector P100 for the coolant temperature sensor or disconnect P103 for the inlet manifold temperature sensor.

2. Turn the keyswitch to the ON position.

   Note: Wait at least 10 seconds for the activation of any diagnostic fault codes.

3. Fabricate a jumper wire 150 mm (6 inch) long. Crimp a terminal to both ends of the wire.

4. Monitor the "Active Diagnostic Code" screen on the electronic service tool before installing the jumper wire and after installing the jumper wire.

5. Install the jumper on the engine harness connector for the suspect sensor, P100 for the coolant temperature sensor and P103 for the intake manifold temperature sensor. Install one end of the jumper at the sensor signal (terminal 1). Install the other end of the jumper at the common connection (terminal 2).

   Note: Wait at least 10 seconds for activation of the Voltage Below Normal diagnostic code.

Expected Result:

A Voltage Below Normal diagnostic code is active when the jumper is installed. A Voltage Above Normal diagnostic code is active when the jumper is removed.

Results:

• OK - The engine harness and the ECM are OK.

  Repair: Perform the following repair:

  1. Temporarily connect the suspect sensor.

  2. If the diagnostic code remains active, replace the sensor.

  3. Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.

  4. Clear all inactive diagnostic codes.

  STOP

• Not OK - The Voltage Above Normal diagnostic code remains active with the jumper in place. The most probable location for the open circuit is in the sensor common or the sensor signal wire in the engine harness between the ECM and the sensor. Remove the jumper. Proceed to Test Step 6.

Test Step 6. Check the Operation of the ECM by Creating an Open and a Short Circuit at the ECM Connector

1. Turn the keyswitch to the OFF position.

2. Disconnect the P2 connector.

3. Thoroughly inspect the P2 connector and the J2 ECM connector for signs of corrosion or moisture. Refer to Troubleshooting, "Electrical Connectors - Inspect".

4. Turn the keyswitch to the ON position. Use the electronic service tool in order to monitor the "Active Diagnostic Code" screen. Wait at least 10 seconds for activation of the code.

   A Voltage Above Normal diagnostic code should be active for the suspect sensor.

   Note: When P2 is disconnected, all of the Voltage Above Normal diagnostic codes for the pressure sensors and temperature sensors will be active. This is normal. Disregard the diagnostic codes for the pressure sensors and the temperature sensors that are not suspect. Monitor the diagnostic codes for the suspect sensors only.

5. Turn the keyswitch to the OFF position.

6. Fabricate a jumper wire 150 mm (6 inch) long. Crimp a terminal to both ends of the wire.

7. Monitor the "Active Diagnostic Code" screen on the electronic service tool before installing the jumper wire and after installing the jumper wire.

8. Remove either pin P2:42 for the intake manifold temperature sensor or pin P2:43 for the coolant temperature sensor.

9. Remove the P2:37 sensor common connector.

10. Install one end of the jumper in P2:37.

11. Install the other end of the jumper at the suspect sensor signal pin.

12. Reassemble the P2 connector to the ECM.

13. Use the electronic service tool in order to check the diagnostic codes. Wait at least 10 seconds for activation of the Voltage Below Normal diagnostic code.

    Note: The Voltage Above Normal diagnostic code for the temperature sensor that is not suspect should become active when the sensor common connection is removed from the P2 connector. Ignore this code.

Expected Result:

A Voltage Below Normal diagnostic code is active when the jumper is installed. A Voltage Above Normal diagnostic code is active when the jumper is removed.

Results:

• OK - Proceed to test step 7.

• Not OK - The ECM does not operate correctly.

  Repair: Perform the following procedure:

  1. Make sure that the latest flash file for the application is installed in the ECM. Refer to Troubleshooting, "Flash Programming".

  2. Contact the Technical Communicator.

     Note: This consultation can greatly reduce the repair time.

  3. If the Technical Communicator recommends the use of a test ECM, install a test ECM. Refer to Troubleshooting, "Replacing the ECM".

  4. Use the electronic service tool to recheck the system for active diagnostic codes.

  5. If the fault is eliminated with the test ECM, reconnect the suspect ECM.

  6. If the fault returns with the suspect ECM, replace the ECM.

  7. Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.

  STOP

Test Step 7. Bypass the Harness Wiring between the ECM and the Sensor Connector

1. Turn the keyswitch to the OFF position.

2. Disconnect the P2 connectorand the connector on the suspect sensor.

3. Remove the signal wire for the suspect sensor from the P2 connector.

4. Remove the signal wire (terminal 1) from the sensor connector on the engine harness.

5. Fabricate a jumper wire that is long enough to reach from the ECM to the sensor connector with sockets on both ends.

6. Insert one end of the jumper into the ECM connector. Insert the other end of the jumper into the sensor connector of the engine harness.

7. Reconnect the connector for the ECM harness and the sensor connector.

8. Turn the keyswitch to the ON position.

9. Use the electronic service tool in order to monitor the "Active Diagnostic Code" screen for either the open circuit diagnostic code for the sensor or the short circuit diagnostic code for the sensor.

10. Remove the jumper and reconnect the wires that were previously removed.

11. Reconnect the P1 connector and the connector for the suspect sensor.

Expected Result:

The diagnostic code disappears when the jumper is installed.

Results:

• OK - There is a fault in the wiring harness.

  Repair: Perform the following repair:

  1. Repair the faulty harness or replace the faulty harness.

  2. Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.

  STOP

• Not OK - The fault is intermittent. Proceed to Test Step 8.

Test Step 8. Perform the "Wiggle Test" on the Electronic Service Tool

1. Select the "Wiggle Test" from the diagnostic tests on the electronic service tool.

2. Choose the appropriate group of parameters to monitor.

3. Press the "Start" button. Wiggle the wiring harness in order to reproduce intermittent faults.

If an intermittent fault exists, the status will be highlighted and an audible beep will be heard.

Expected Result:

No intermittent faults were indicated during the "Wiggle Test".

Results:

• OK - No intermittent faults were found. The harness and connectors appear to be OK. If this test has not identified a fault, return the engine to service.STOP

• Not OK - At least one intermittent fault was indicated.

  Repair: Repair the harness or the connector.Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.

  STOP