3408E and 3412E Engines for Caterpillar Built Machines Caterpillar

Use this procedure to troubleshoot any suspect problems with the analog engine sensor circuits.

This procedure covers the following diagnostic codes:

• 100-03 Engine Oil Pressure open/short to +batt

• 100-04 Engine Oil Pressure short to ground

• 110-03 Engine Coolant Temperature open/short to +batt

• 110-04 Engine Coolant Temperature short to ground

• 164-03 Injector Actuation Pressure voltage high

• 164-04 Injector Actuation Pressure voltage low

• 172-03 Intake Manifold Air Temp open/short to +batt

• 172-04 Intake Manifold Air Temp short to ground

• 174-03 Fuel Temperature open/short to +batt

• 174-04 Fuel Temperature short to ground

• 175-03 Engine Oil Temperature open/short to +batt

• 175-04 Engine Oil Temperature short to ground

• 273-03 Turbo Outlet Pressure open/short to +batt

• 273-04 Turbo Outlet Pressure short to ground

• 274-03 Atmospheric Pressure open/short to +batt

• 274 -04 Atmospheric Pressure short to ground

• 275-03 Right Turbo Inlet Pressure open/short to +batt

• 275-04 Right Turbo Inlet Pressure short to ground

The troubleshooting procedures for the diagnostic codes of each pressure sensor are identical. The Electronic Control Module (ECM) sends a 5 Volt supply to terminal A of each sensor. The sensor common connection is connected to terminal B of each sensor. The signal voltage from terminal C of each sensor is sent to the appropriate terminal at the J1/P1 ECM connector or the J2/P2 ECM connector.

The ECM performs an automatic calibration of these sensors whenever the ECM is powered and the engine is off for at least five seconds. During an automatic calibration, the ECM calibrates pressure sensors against the atmospheric pressure sensor. If the offset is within an acceptable offset pressure range, the offset is stored in ECM memory.

Note: Refer to Troubleshooting, "Analog Sensor Supply Circuit - Test" if the ECM has detected a problem with the analog sensor supply voltage.

Illustration 1	g01163938
Schematic

Test Step 1. Inspect the Electrical Connectors and the Wiring

1. Turn the keyswitch to the OFF/RESET position.

2. Thoroughly inspect ECM connector J1/P1, ECM connector J2/P2, machine connector J3/P3, and all other connectors in the wiring harness. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

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

4. Check the allen head screw for each ECM connector for the proper torque of 2.25 ± 0.25 N·m (20 ± 2 lb in).

5. Check the harness and wiring for abrasions and for pinch points from the sensors back to the ECM.

Expected Result:

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

Results:

• OK - Proceed to Test Step 2.

• Not OK - There is a problem in the connectors and/or wiring.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the problem.

  STOP

Test Step 2. Check the Supply Voltage at the Sensor Connector

1. Disconnect the suspect sensor.

2. Turn the keyswitch to the ON position.

3. Use a multimeter to measure the voltage across terminal A (+5V analog supply) and terminal B (sensor return) at the harness side of the suspect sensor connector.

4. Turn the keyswitch to the OFF/RESET position.

5. Reconnect all sensors.

Expected Result:

The voltage is 5.0 ± 0.2 VDC.

Results:

• OK - The voltage is 5.0 ± 0.2 VDC. The voltage is correct. Proceed to Test Step 3.

• Not OK - The voltage is not 5.0 ± 0.16 VDC.

  Repair: The voltage is incorrect. Refer to Troubleshooting, "Analog Sensor Supply Circuit - Test" for the appropriate troubleshooting procedure.

  STOP

Test Step 3. Check for Active Diagnostic Codes

1. Connect Caterpillar Electronic Technician (ET) to the service tool connector.

2. Turn the keyswitch to the ON position.

3. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.

   Note: Wait at least 15 seconds in order for the diagnostic codes to become active.

4. Determine if the problem is related to an open circuit diagnostic code 03 or a short circuit diagnostic code 04.

5. Turn the keyswitch to the OFF/RESET position.

Expected Result:

No diagnostic codes are active.

Results:

• OK - No diagnostic codes are active.

  Repair: The problem may have been related to a faulty connection in the harness. Carefully reinspect the connectors and wiring. Refer to Troubleshooting, "Electrical Connectors - Inspect".

  STOP

• Not OK - A short circuit diagnostic code (04) is active at this time. Proceed to Test Step 4.

• Not OK - An open circuit diagnostic code (03) is active at this time. Proceed to Test Step 5.

Test Step 4. Disconnect the Suspect Sensor in Order to Create an Open Circuit

1. Disconnect the sensor connector of the sensor with the short circuit diagnostic code (04).

2. Turn the keyswitch to the ON position. Wait at least 15 seconds for activation of the diagnostic codes.

3. Access the "Active Diagnostic Code" screen on Cat ET. Check for an active open circuit diagnostic code (03).

4. Turn the keyswitch to the OFF/RESET position.

Expected Result:

An open circuit diagnostic code 03 is now active for the disconnected sensor.

Results:

• OK - A short circuit diagnostic code (04) was active before disconnecting the sensor. An open circuit diagnostic code (03) became active after disconnecting the sensor.

  Repair: Temporarily connect a new sensor to the harness, but do not install the new sensor in the engine. Verify that there are no active diagnostic codes for the sensor. If there are no active diagnostic codes for the sensor, permanently install the new sensor. Clear any logged diagnostic codes.

  STOP

• Not OK - There is a short circuit between the sensor harness connector and the ECM. Leave the sensor disconnected. Proceed to Test Step 7.

Test Step 5. Check the Signal Wire for a Short Circuit

1. Turn the keyswitch to the OFF position.

2. Disconnect ECM connectors P1 and P2.

3. Disconnect the connector for the sensor.

4. Measure the resistance between the terminal for the sensor signal wire at the ECM and every terminal on ECM connector P1 and ECM connector P2.

5. Measure the resistance between the terminal for the sensor signal wire at the ECM and engine ground.

6. Turn the keyswitch to the OFF/RESET position.

7. Reconnect ECM connector P1 and ECM connector P2.

Expected Result:

The resistance indicates an open circuit for all measurements.

Results:

• OK - An open circuit was indicated for all measurements. Proceed to Test Step 6.

• Not OK - An open circuit was not indicated for at least one measurement.

  Repair: The resistance measurement indicates a low resistance between two or more wires. Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

Test Step 6. Create a Short at the Suspect Sensor Connector

1. Turn the keyswitch to the OFF/RESET position.

2. Install a jumper wire between terminal B (sensor return) and terminal C (sensor signal) on the connector for the suspect sensor. Connect the jumper on the harness side of the connector.

3. Turn the keyswitch to the ON position.

4. Wait at least 15 seconds for activation of the short circuit diagnostic code 04.

   Note: Monitor the "Active Diagnostic Codes" screen on Cat ET before installing the jumper wire and after installing the jumper wire.

5. Remove the jumper wire.

6. Turn the keyswitch to the OFF/RESET position.

Expected Result:

A short circuit diagnostic code 04 is active when the jumper wire is installed. An open circuit diagnostic code 03 is active when the jumper wire is removed.

Results:

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

  Repair: Temporarily connect a new sensor to the harness, but do not install the new sensor in the engine. Verify that there are no active diagnostic codes for the sensor. If there are no active diagnostic codes for the sensor, permanently install the new sensor. Clear any logged diagnostic codes.

  STOP

• Not OK - The open circuit diagnostic code 03 remains active with the jumper in place. The open circuit is between the ECM and the sensor connector. Proceed to Test Step 7.

Test Step 7. Check the Operation of the ECM

1. Turn the keyswitch to the OFF/RESET position.

2. Check the operation of the ECM by creating an open at the ECM.

   1. Remove the signal wire for the suspect sensor from the appropriate ECM connector.

   2. Fabricate a jumper wire that is long enough to be installed between the suspect sensor's signal terminal at the ECM and the engine ground stud. Install a connector socket to one end of the jumper wire.

   3. Install the jumper wire into the appropriate terminal location of the ECM connector.

   4. Reconnect the ECM connector.

   5. Turn the keyswitch to the ON position. Monitor the "Active Diagnostic Code" screen on Cat ET. Wait at least 15 seconds for activation of the code.

      An open circuit diagnostic code (03) is active for the suspect sensor.

3. Check the operation of the ECM by creating a short at the ECM.

   1. Ground the jumper wire that is installed in the ECM connector to the engine ground stud.

   2. Monitor the "Active Diagnostic Code" screen on Cat ET. Wait at least 15 seconds for activation of the code.

      A short circuit diagnostic code (04) is active when the jumper wire is installed.

   3. Remove the jumper wire and reconnect all wires.

Expected Result:

An open circuit diagnostic code 03 is active when the sensor signal wire is open at the ECM connector. A short circuit diagnostic code 04 is active when the signal wire is connected to the engine ground stud.

Results:

• OK - The ECM is operating properly. The problem is in the wiring between the ECM and the sensor connector.

  Repair: If the code is active for more than one sensor, the problem is most likely in the return wire for the sensor. Repair the return wire for the sensor or replace the harness.If the code is only active for one sensor, the problem is most likely in the signal wire for the sensor. Repair the signal wire for the sensor.

  STOP

• Not OK - One of the following conditions exists: The open circuit diagnostic code 03 is not active when the sensor signal wire is disconnected. The short circuit diagnostic code 04 is not active when the wire jumper is grounded.

  Repair: Replace the ECM. Refer to Troubleshooting, "Replacing the ECM". Verify that the problem is resolved.

  STOP