C-10 and C-15 Petroleum Engines Caterpillar

Use this procedure to troubleshoot any suspect problems with the following sensors:

• Fuel pressure sensor

• Engine oil pressure sensor

• Turbocharger outlet pressure sensor

• Atmospheric pressure sensor

• Auxiliary pressure sensor

This procedure covers the following open circuit diagnostic codes and short circuit diagnostic codes:

• 94-03

• 94-04

• 100-03

• 100-04

• 273-03

• 273-04

• 274-03

• 274-04

• 1835-03

• 1835-04

The troubleshooting procedures for the diagnostic codes of each pressure sensor are identical. The Electronic Control Module (ECM) supplies 5 ± 0.2 VDC 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 on the ECM.

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 (-03) for the sensor.

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

Illustration 1	g01145390
Schematic for C-10 engines

Illustration 2	g01148768
Schematic for C-15 engines

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The connection of any electrical equipment and the disconnection of any electrical equipment may cause an explosion hazard which may result in injury or death. Do not connect any electrical equipment or disconnect any electrical equipment in an explosive atmosphere.

Test Step 1. Inspect the Electrical Connectors and the Wiring

1. Turn the keyswitch to the OFF position.

2. Thoroughly inspect all connectors that are associated with the +5 V sensor supply for your engine. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
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   Illustration 3	g01145553
   C-10 engine (left side engine view) (1) Fuel pressure sensor (2) Atmospheric pressure sensor (3) Turbocharger outlet pressure sensor (4) P61 customer connector (5) Engine oil pressure sensor (6) ECM (7) P2/J2 ECM connector (8) P1/J1 ECM connector

   1. For C-10 engines, inspect connectors (4), (7), and (8). Also inspect each of the connectors for sensors (1), (2), (3), and (5) .
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   Illustration 4	g01145557
   C-15 engine (left side engine view) (9) P61 customer connector (10) Turbocharger outlet pressure sensor (11) Fuel pressure sensor (12) Atmospheric pressure sensor (13) Engine oil pressure sensor (14) ECM (15) P2/J2 ECM connector (16) P1/J1 ECM connector

   2. For C-15 engines, inspect connectors (9), (15), and (16). Also inspect each of the connectors for sensors (10), (11), (12), and (13) .

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Illustration 5	g01145450
P2 ECM connector for C-10 and C-15 engines (P2-2) +5 V Sensor supply (P2-3) Sensor return (P2-14) Atmospheric pressure sensor (P2-16) Fuel pressure sensor (P2-24) Engine oil pressure sensor (P2-40) Turbocharger outlet pressure sensor

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Illustration 6	g01145447
P1 ECM connector for C-10 and C-15 engines (P1-2) +5 V Sensor supply (P1-3) Sensor return (P1-15) Auxiliary pressure sensor

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Illustration 7	g01145543
P61 Customer connector (P61-2) +5 V Sensor supply (P61-3) Sensor return (P61-15) Auxiliary pressure sensor

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Illustration 8	g01123211
Connectors for the sensors (A) +5 V Sensor supply (B) Sensor return (C) Signal

3. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the +5 V sensor supply.

4. Check the torque of the allen head screw on the ECM connectors and the customer connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.

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

Expected Result:

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

Results:

• OK - The harness and connectors appear to be OK. Proceed to Test Step 2.

• Not OK - The connectors and/or wiring are not OK.

  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. Turn the keyswitch to the OFF position.

2. Disconnect all of the following analog sensors at the sensor connector:
   • Turbocharger outlet pressure sensor J200/P200

   • Atmospheric pressure sensor J203/P203

   • Engine oil pressure sensor J201/P201

   • Fuel pressure sensor J209/P209

   • Auxiliary pressure sensor J220/P220

3. Turn the keyswitch to the ON position.

4. Measure the voltage between terminal A (+5 V sensor supply) and terminal B (sensor return) at the sensor connectors.

5. Turn the keyswitch to the OFF position.

6. Reconnect all sensors.

Expected Result:

The voltage is 5.0 ± 0.2 VDC.

Results:

• OK - The voltage is correct. Proceed to Test Step 3.

• Not OK - The voltage is incorrect.

  Repair: Perform the diagnostic functional test Troubleshooting, "5 Volt Engine Pressure Sensor Supply Circuit - Test".

  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. Check for active diagnostic codes. 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.

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 the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".

  STOP

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

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

Test Step 4. Disconnect the Suspect 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 short circuit diagnostic code (-04).

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

4. Use Cat ET to check for an active open circuit diagnostic code (-03).

5. Turn the keyswitch to the OFF 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 8.

Test Step 5. Check the Pull-up Voltage at the Sensor Connector

1. Turn the keyswitch to the ON position.

2. Measure the voltage between terminal C (signal) and terminal B (sensor return) at the sensor connector.

3. Turn the keyswitch to the OFF position.

Expected Result:

The voltage is 11 ± 2 VDC.

Results:

• OK - The voltage is correct. The signal wire to the ECM from the sensor connector is OK.

  Repair: The open circuit is in the sensor or the wire between the sensor and the sensor connector. Replace the sensor. Do not install the sensor in the engine. Verify that no diagnostic codes are active for the suspect sensor before permanently installing the sensor.

  STOP

• Not OK - The voltage is incorrect. Proceed to Test Step 6.

Test Step 6. Verify that the Circuit is not Shorted to a Voltage Source

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. Reconnect ECM connector P1 and ECM connector P2.

Expected Result:

The correct measurement is an open circuit for all measurements.

Results:

• OK - All measurements indicated an open circuit. Proceed to Test Step 7.

• Not OK - At least one of the measurements indicated a resistance between the wires that are in the harness.

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

  STOP

Test Step 7. Create a Short at the Suspect Sensor Connector

1. Turn the keyswitch to the OFF position.

2. Use a jumper wire to short terminal B (sensor return) and terminal C (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: Use Cat ET to check for active diagnostic codes before installing the jumper wire and after installing the jumper wire.

5. Remove the jumper wire.

6. Turn the keyswitch to the OFF 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 8.

Test Step 8. Check the Operation of the ECM by Creating Open and Short Circuits at the ECM Connector

1. Turn the keyswitch to the OFF position.

2. Disconnect the J1/P1 or the J2/P2 ECM connector. Thoroughly inspect both halves of the connectors for signs of corrosion or moisture.

3. Remove the signal wire for the suspect sensor from either the J1/P1 or the J2/P2 ECM connector. Install a wire jumper with a socket on one end into the ECM connector for the signal wire.

4. Remove the analog return for the suspect sensor from either the J1/P1 or the J2/P2 ECM connector. Install a wire jumper with a socket on one end into the ECM connector for the return wire.

   Note: Disconnecting the sensor return from the ECM will generate an open circuit diagnostic code for all sensors that are connected to the sensor return. Troubleshoot the original diagnostic code. Delete the logged diagnostic codes when you are finished.

5. Reconnect the ECM connector.

6. 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 (-03) should be active for the suspect sensor.

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

8. Install a wire jumper between the two jumper wires that were inserted into the ECM connector for the sensor signal and the sensor return.

9. 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 (-04) should be active when the wire jumper is installed.

10. Remove the wire jumpers and replace all wires. Reconnect ECM connector J1/P1 and J2/P2.

Expected Result:

An open circuit diagnostic code -03 is active when the sensor signal wire is removed from the ECM connector. A short circuit diagnostic code -04 is active when the signal wire is connected to the sensor return.

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 installed.

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

  STOP