C-10 and C-15 Petroleum Engines Caterpillar

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

• Primary engine speed/timing sensor

• Secondary engine speed/timing sensor

This procedure covers the following diagnostic codes:

• 320-02 Speed/Timing Sensor Loss of Signal

• 320-11 Speed/Timing Sensor Mechanical failure

• 342-02 Loss of signal

• 342-11 Secondary Engine Speed Sensor mechanical failure

The engine uses two engine speed/timing sensors. The secondary engine speed/timing sensor picks up the camshaft gear and the primary engine speed/timing sensor picks up the crankshaft gear. Both of the engine speed/timing sensors detect the reference for engine speed and timing from a unique pattern on the respective gear. The Electronic Control Module (ECM) counts the time between pulses that is created by the sensor as the gear rotates in order to determine rpm.

Under normal operation, the secondary engine speed/timing sensor is used to determine timing for starting purposes. The secondary engine speed/timing sensor is used to determine when the piston in the No. 1 cylinder is at the top of the compression stroke. When the timing has been established, the primary engine speed/timing sensor is then used to determine engine speed and the signal from the secondary engine speed/timing sensor is ignored.

After locating the No. 1 cylinder, the ECM triggers each injector in the correct firing order and at the correct unit injector timing. The actual timing and duration of each injection is based on engine rpm and on load. If the engine is running and the signal from the primary engine speed/timing sensor is lost, a slight change in engine performance will be noticed when the ECM performs the changeover to the secondary engine speed/timing sensor. Loss of the signal from the secondary engine speed/timing sensor during engine operation will not result in any noticeable change in engine performance. However, if the signal from the secondary engine speed/timing sensor is not present during start-up the following conditions may exist:

• The engine may require a slightly longer period of time to start-up.

• The engine may run rough for a few seconds until the ECM determines the proper firing order by using the primary engine speed/timing sensor only.

The engine will start and the engine will run when only one sensor signal is present from either of the sensors. The loss of the signal from both of the sensors during engine operation will result in the termination of injection and the shutting down of the engine by the ECM. The loss of the signal from both of the sensors during start-up will prevent the engine from starting.

Both sensors are magnetic sensors with an integral connector. The two sensors are not interchangeable. Do not switch the positions of the sensor. If the sensors are replaced, a timing calibration is not necessary for the engine.

Note: When the sensors are being installed, complete all of the following tasks:

• Lubricate the O-ring with oil.

• Ensure that the sensor is fully seated into the engine before tightening the bracket bolt.

• Ensure that the connector is properly latched.

• Ensure that the harness is properly secured, and ensure that the tie-wraps are placed in the correct location.

Illustration 1	g01146558
C-10 schematic for engine speed/timing

Illustration 2	g01081655
C-15 schematic for engine speed/timing

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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 Electrical Connectors and Wiring

1. Turn the keyswitch to the OFF position.

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Illustration 3	g01146562
C-10 sensor locations (left side engine view) (1) J1/P1 ECM connector (2) Secondary engine speed/timing sensor (3) Primary engine speed/timing sensor

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Illustration 4	g01146568
C-15 sensor locations (left side engine view) (1) J1/P1 ECM connector (2) Secondary engine speed/timing sensor (3) Primary engine speed/timing sensor

2. Thoroughly inspect ECM connector (1). Also, thoroughly inspect the connectors for sensors (2) and (3) .

   Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" for details.

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Illustration 5	g01146574
P2 connector (P2-48) Primary engine speed/timing signal (+) (P2-49) Primary engine speed/timing signal (−) (P2-58) Secondary engine speed/timing signal (+) (P2-59) Secondary engine speed/timing signal (−)

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 circuit.

4. Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

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 - The harness and wiring are 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 for Active Diagnostic Codes

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

2. Turn the keyswitch to the ON position.

3. Verify whether any of the following diagnostic codes are active or logged:
   • 320-02

   • 320-11

   • 342-02

   • 342-11

4. If the diagnostic code is logged but not active, run the engine until the engine is at normal operating temperature. The problem may only occur when the engine is at the normal operating temperature.

5. If the engine will not start, monitor the engine speed on Cat ET while the engine is being cranked. Cat ET may need to be powered from another battery while the engine is being cranked in order to ensure that Cat ET does not reset.

   Note: Upon initial cranking, the status for engine speed may indicate that the engine speed signal is abnormal. This message will be replaced with an engine speed once the ECM is able to calculate a speed from the signal.

Expected Result:

One or more of the diagnostic codes that are listed above are logged or active.

Results:

• Active Code - There is an active code for an engine speed/timing sensor. Proceed to Test Step 4.

• Logged Code - There is a logged code for an engine speed/timing sensor. Proceed to Test Step 6.

• No Engine rpm - Engine rpm is not indicated on Cat ET. Proceed to Test Step 3.

Test Step 3. Inspect the Sensor Assembly

Illustration 6	g01142103
Engine speed/timing sensors (4) Bracket (5) Secondary speed/timing sensor (6) Mounting plate (7) O-ring seals (8) Bracket (9) Primary speed/timing sensor

1. The flange of the sensor should be flush against the engine in order to ensure proper operation.

2. Inspect the bracket in order to ensure that the installation allows the flange of the sensor to be flush against the engine.

   Verify that the bracket is not bent.

   Note: The bracket cannot be replaced separately.

3. Ensure that the O-ring has been installed on the sensor, and ensure that the O-ring is free of damage.

4. If either of the following diagnostic codes is active, there may be a problem with the assembly of the camshaft gear or the crankshaft gear:
   • 320-11

   • 342-11

Expected Result:

The sensors and the bracket are properly installed.

Results:

• OK - The sensors and the bracket are properly installed. Proceed to Test Step 4.

• Not OK -

  Repair: Perform the following procedure in order to properly install the sensors and the bracket:

  1. Loosen the bolt that holds the sensor mounting bracket to the engine.

  2. Seat the sensor and tighten the bolt.

     If the sensor will not seat, repair the sensor or replace the sensor, as required.

     Note: The sensor must not be removed from the bracket.

  3. Ensure that the sensor is properly oriented and that the harness is secured in the proper location.

  4. Verify that the repair eliminates the problem.

  STOP

Test Step 4. Measure the Sensor Resistance through the Engine Harness

1. Turn the keyswitch to the OFF position.

2. Use the following procedure to measure the circuit resistance for the primary engine speed/timing sensor:

   1. Measure the resistance between terminal P2-48 (primary engine speed/timing +) and terminal P2-49 (primary engine speed/timing −).

      Note: Check for an intermittent problem (open or short) by moving the harness while you measure the resistance. Pull the wires that are directly behind the sensors and shake the wires that are directly behind the sensors.

      Resistance ... 110 to 200 Ohms

3. Use the following procedure to measure the circuit resistance for the secondary engine speed/timing sensor:

   1. Measure the resistance between terminal P2-58 (secondary engine speed/timing +) and terminal P2-59 (secondary engine speed/timing −).

      Note: Check for an intermittent problem (open or short) by moving the harness while you measure the resistance. Pull the wires that are directly behind the sensors and shake the wires that are directly behind the sensors.

      Resistance ... 1000 to 1200 Ohms

Expected Result:

The readings agree with the values that are listed above.

Results:

• OK - Neither a short circuit nor an open circuit is indicated. Proceed to Test Step 7.

• Not OK - The resistance is not within the acceptable range when the circuit resistance is measured through the engine harness. Proceed to Test Step 5.

Test Step 5. Measure the Resistance of the Sensor

1. Turn the keyswitch to the OFF position.

2. Check the harness and the wiring for abrasion and pinch points from the sensor back to the ECM.

3. Disconnect the suspect sensor from the engine harness.

4. Thoroughly inspect the connector for the suspect engine speed/timing sensor. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" for details.

5. Use the following procedure to measure the resistance of the primary engine speed/timing sensor:

   1. Disconnect the J401/P401 primary engine speed/timing sensor connector.

   2. Measure the resistance between terminal 1 and terminal 2 of the sensor.

      Resistance ... 110 to 200 Ohms

6. Use the following procedure to measure the resistance of the secondary engine speed/timing sensor:

   1. Disconnect the J402/P402 secondary engine speed/timing sensor connector.

   2. Measure the resistance between terminal 1 and terminal 2 of the sensor.

      Resistance ... 1000 to 1200 Ohms

Expected Result:

The resistance measurement for the suspect sensor is within the specification.

Results:

• OK - The resistance measurement for the suspect sensor is within the specification. The sensor's resistance measurement at the P2 connector was incorrect. There is a problem with the wiring. There may be a problem with a connector.

  Repair: Repair the connection and/or the wiring, when possible. Replace parts, if necessary. Twisted pair wiring is required. The wiring must have at least one twist per inch. Verify that the problem is resolved.

  STOP

• Not OK - The resistance measurement for the suspect sensor is not within the specification. There is a problem with the sensor.

  Repair: Replace the sensor assembly.Do not switch the positions of the sensors. The sensors are not interchangeable. A timing calibration is not required when the sensors are replaced. Perform the following procedure in order to replace the sensor assembly:

  1. Lubricate the O-ring seal with oil.

  2. Fully seat the sensor into the housing.

  3. Tighten the bracket bolt.

  4. Connect the connector and verify that the latch tab of the connector is latched on both sides.

  5. Ensure that the harness is properly secured, and ensure that the harness is attached to the harness clip.
  Verify that the problem is resolved.

  STOP

Test Step 6. Check the Wiring

1. Start the engine and run the engine. The problem may occur when the engine is at any operating temperature. However, the problem is more likely to occur when the engine is at the normal operating temperature.

2. Wiggle the wires in the harness in order to check for an intermittent problem. Be sure to wiggle the wires near each of the connectors. Look for a diagnostic code. The engine may run rough or the engine may become unstable.

Expected Result:

A diagnostic code for the engine speed/timing sensor is activated or the engine becomes unstable.

Results:

• Yes - A diagnostic code for the engine speed/timing sensor is activated or the engine became unstable. There could be a problem with the wiring or with a connector.

  Repair: Repair the connection and/or the wiring, when possible. Replace parts, if necessary. Twisted pair wiring is required. The wiring must have at least one twist per inch. Verify that the problem is resolved.

  STOP

• No - A diagnostic code for the engine speed/timing sensor is not activated. The engine operated smoothly. The original problem seems to be resolved.

  Repair: The original diagnostic code was probably caused by a poor electrical connection. Reconnect the engine harness to the good sensor. Clear the diagnostic codes. Resume normal operation.

  STOP

Test Step 7. Check the Sensor

1. Temporarily replace the suspect sensor. Perform the following procedure in order to replace the sensor assembly.

   Note: Do not switch the positions of the sensors. The sensors are not interchangeable. A timing calibration is not required when the sensors are replaced.

   1. Lubricate the O-ring seals with oil.

   2. Fully seat the sensor into the front housing.

   3. Tighten the bracket bolt.

   4. Connect each connector and verify that the latch tab of each connector is latched on both sides.

   5. Ensure that the harness is properly secured, and ensure that the harness is attached to the harness clip.

2. Reconnect all of the connectors.

3. Clear any diagnostic codes.

4. Start the engine. Run the engine until the engine is at normal operating temperature. The problem may only occur when the engine is at the normal operating temperature.

Expected Result:

No diagnostic codes for the engine speed/timing sensor are activated.

Results:

• OK - No diagnostic codes for the engine speed/timing sensor are activated. Resume normal operation.STOP

• Not OK - The diagnostic code for the engine speed/timing sensor remains. Replacing the sensor did not solve the problem. There may be a problem with the ECM.

  Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. If the problem is not resolved, install a new ECM. Refer to Troubleshooting, "Replacing the ECM". Verify that the original problem is resolved.

  STOP