Use this procedure to troubleshoot the system only when there is an active diagnostic code or when a diagnostic code can easily be activated. This procedure covers the following diagnostic codes that are connected to the engine's Electronic Control Module (ECM):
- 94-03 Fuel Pressure open/short to +batt
- 94-04 Fuel Pressure short to ground
- 100-03 Engine Oil Pressure open/short to +batt
- 100-04 Engine Oil Pressure short to ground
- 102-03 Turbocharger Outlet (Boost) Pressure Sensor open/short to +batt
- 102-04 Turbocharger Outlet (Boost) Pressure Sensor short to ground
- 274-03 Atmospheric Pressure open/short to +batt
- 274-04 Atmospheric Pressure short to ground
- 164-03 Injector Actuation Pressure open/short to +batt
- 164-04 Injector Actuation Pressure short to ground
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| Illustration 1 | g01157918 |
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| Illustration 2 | g01157919 |
Test Step 1. Check for Active +5 V Sensor Supply Diagnostic Codes
- Connect Caterpillar Electronic Technician (ET) to the service tool connector.
- Turn the keyswitch to the ON position. Wait at least 15 seconds for activation of the diagnostic codes.
- Verify that neither of the following diagnostic codes are active:
- 262-03
- 262-04
- 262-03
Expected Result:
Neither of the preceding diagnostic codes are active.
Results:
- OK - The diagnostic codes are not active. Proceed to Test Step 2.
- Not OK - At least one of the diagnostic codes is active.
Repair: Perform the following diagnostic procedure: Troubleshooting, "Analog Sensor Supply Circuit - Test".
STOP
Test Step 2. Verify all Active Diagnostic Codes
- Turn the keyswitch to the ON position. Wait at least 15 seconds for activation of the diagnostic codes.
- Verify if any diagnostic codes are active:
Expected Result:
One or more diagnostic codes are active.
Results:
- OK - One or more of the diagnostic codes are active. Proceed to Test Step 3.
- Not OK - None of the diagnostic codes are active.
Repair: If the preceding codes are logged but not active and the engine is not running properly, refer to Troubleshooting, "Troubleshooting without a Diagnostic Code". If the engine is running properly at this time, an intermittent condition may be causing the logged codes. Refer to Troubleshooting, "Electrical Connectors - Inspect".
STOP
Test Step 3. Inspect the Electrical Connectors and the Wiring
- Turn the keyswitch to the OFF position.
- Thoroughly inspect the J2/P2 ECM connector and the connectors for each pressure sensor. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
- 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.
- Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
- 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 - The connectors and wiring are OK. Proceed to Test Step 4.
- Not OK - The connectors or wiring are damaged.
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.Clear all logged diagnostic codes.
STOP
Test Step 4. Verify that a Diagnostic Code is Still Active
- Turn the keyswitch to the ON position. Wait at least 15 seconds for activation of the diagnostic codes.
- Monitor the "Active Diagnostic Code " screen on the electronic service tool. Record any active diagnostic codes.
- Determine if the problem is related to an open circuit diagnostic code or to a short circuit diagnostic code.
Expected Result:
Either a short circuit diagnostic code is active or an open circuit diagnostic code is active.
Results:
- SHORT Circuit - A short circuit diagnostic code is active at this time. Proceed to Test Step 5.
- OPEN Circuit - An open circuit diagnostic code is active at this time. Proceed to Test Step 6.
Test Step 5. Disconnect the Sensor in Order to Create an Open Circuit
- Turn the keyswitch to the OFF position.
- Disconnect the sensor connector of the sensor with the short circuit diagnostic code.
- Turn the keyswitch to the ON position. Wait at least 15 seconds for activation of the diagnostic codes.
- Access the "Active Diagnostic Code" screen on the electronic service tool. Check for an active open circuit diagnostic code.
Expected Result:
An open circuit diagnostic code is now active for the disconnected sensor.
Results:
- OK - A short circuit diagnostic code was active before disconnecting the sensor. An open circuit diagnostic code became active after disconnecting the sensor. Proceed to Test Step 7.
- Not OK - There is a short circuit between the sensor harness connector and the ECM. Leave the sensor disconnected. Proceed to Test Step 9.
Test Step 6. Measure the Sensor Supply Voltage
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| Illustration 3 | g00810608 |
Terminals for pressure sensors | |
- Turn the keyswitch to the OFF position.
- Disconnect the sensor from the engine harness.
- Turn the keyswitch to the ON position.
- Measure the voltage from terminal "A" (Analog Sensor Power +5V) to terminal "B" (Analog Sensor Common) on the engine harness side of the connector.
Expected Result:
The voltage between terminal "A" and terminal "B" measures 5.0 ± 0.2.
Results:
- OK - The sensor supply voltage is correct. Proceed to Test Step 8.
- Not OK - The sensor supply voltage is out of the specified range.
Repair: Proceed to the following procedure: Troubleshooting, "Analog Sensor Supply Circuit - Test"
STOP
Test Step 7. Determine if the Short Circuit is in the Connector or in the Sensor
- Thoroughly inspect the connector for moisture.
- Inspect the seals and reconnect the sensor.
- If the short circuit diagnostic code reappears, the sensor or the pigtail harness connector is the problem.
- Temporarily connect a new sensor to the harness, but do not install the new sensor in the engine.
- Check for a short circuit diagnostic code while the new sensor is connected to the harness.
Expected Result:
The short circuit diagnostic code is not present when a new sensor is connected.
Results:
- OK - The short circuit diagnostic code is not present when a new sensor is connected.
Repair: Permanently install the new sensor. Clear the logged diagnostic codes.
STOP
- Not OK - The short circuit diagnostic code is present.
Repair: Repair the engine harness connector. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
STOP
Test Step 8. Create a Short Circuit Between the Signal and the Common Terminals at the Engine Harness Connector
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| Illustration 4 | g00810608 |
Terminals for pressure sensors | |
- Turn the keyswitch to the OFF position.
- Fabricate a jumper wire 150 mm (6 inch) long.
- Turn the keyswitch to the ON position.
- Monitor the "Active Diagnostic Code" screen on the electronic service tool before installing the jumper wire and after installing the jumper wire.
- Install the jumper on the engine harness connector for the suspect sensor. Install one end of the jumper in terminal C (Signal). Install the other end of the jumper in terminal B (Common). Wait at least 15 seconds for activation of the short circuit diagnostic code.
Expected Result:
A short circuit diagnostic code is active when the jumper is installed. An open circuit diagnostic code is active when the jumper is removed.
Results:
- OK - The engine harness and the ECM are OK.
Repair: Perform the following repair:
- Temporarily connect the suspect sensor.
- If the diagnostic code remains active, replace the sensor.
- Ensure that the diagnostic code is no longer active.
- Verify that the repair eliminates the problem.
STOP
- Not OK - The open circuit diagnostic code remains active when the jumper is installed. The most probable location for the open 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 9.
Test Step 9. Check the Operation of the ECM by Creating Open and Short Circuits at the ECM Connector
- Turn the keyswitch to the OFF position.
- Disconnect the J2/P2 ECM connector. Thoroughly inspect both halves of the connectors for signs of corrosion or moisture.
- Remove the signal wire for the suspect sensor from the J2/P2 ECM connector.
- Reconnect the J2/P2 ECM connector.
- Turn the keyswitch to the ON position. Monitor the "Active Diagnostic Code" screen on the electronic service tool. Wait at least 15 seconds for activation of the code.
An open circuit diagnostic code should be active for the suspect sensor.
- Turn the keyswitch to the OFF position.
- Fabricate a jumper wire approximately 150 mm (6 inch) long. Install an alligator clamp on one end of the wire.
- Insert the end of the jumper wire in the terminal for the suspect sensor signal. Connect the alligator clamp to the ECM ground strap.
- Turn the keyswitch to the ON position. Monitor the "Active Diagnostic Code" screen on the electronic service tool. Wait at least 15 seconds for activation of the code.
A short circuit diagnostic code should be active when the jumper wire is installed.
Expected Result:
An open circuit diagnostic code is active when the sensor's signal wire is disconnected. A short circuit diagnostic code is active when the jumper wire is installed.
Results:
- OK - The ECM is operating properly. There is a problem in the harness.
Repair: Repair the harness. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
STOP
- Not OK - The ECM is not responding properly.
Repair: Perform the following repair:
- Temporarily connect a spare ECM.
- Remove all jumpers and replace all connectors.
- Recheck the system for active diagnostic codes.
- If the problem is resolved with the spare ECM, reconnect the suspect ECM.
- If the problem returns with the suspect ECM, replace the ECM. Refer to the diagnostic procedure Troubleshooting, "Replacing the ECM".
- Verify that the repair eliminates the problem.
STOP