3406E, C12, C15 and C18 Marine 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 Secondary Engine Speed signal

• 342-11 Secondary Engine Speed Sensor mechanical failure

The engine uses two engine speed/timing sensors. The primary engine speed/timing sensor detects the reference for engine speed and timing from a unique pattern on the crankshaft gear. The secondary engine speed/timing sensor detects the reference for engine speed and timing from a unique pattern on the camshaft 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.

When the timing has been established, the ECM triggers each injector in the correct firing order at the correct time. The actual timing and duration of each injection is based on the engine rpm, on the load, and on the position of the throttle.

If the engine is running and the signal from one sensor is lost, no noticeable change in engine performance will be noticed. If the engine is running and the signals from both sensors are lost, fuel injection will be terminated and the engine will be shut down by the ECM.

The engine will start when only one sensor signal is present. The engine will not start if the signals from both sensors are lost.

Both sensors are magnetic sensors. The two sensors are not interchangeable. If a sensor is replaced, a timing calibration is not necessary.

If a replacement of the ECM is required, the ECM parameters and the timing calibration can be transferred from the suspect ECM to the replacement ECM. Timing calibration will not be necessary. This feature requires the Caterpillar Electronic Technician (ET) and this feature is only possible if the existing ECM can communicate with Cat ET. Use the "Copy Configuration - ECM Replacement" feature on Cat ET.

Complete all of the following tasks when you install a speed/timing sensor:

• Ensure that an O-ring is installed on the sensor. If the O-ring is damaged or missing, replace the O-ring.

• Lubricate the O-ring with oil.

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

• Ensure that the electrical connector is latched.

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

Illustration 1	g01150285
Schematic for speed/timing sensors

Test Step 1. Check for Active Diagnostic Codes

1. Ensure that the keyswitch is in the OFF position.

2. Connect Cat ET to the service tool connector.

3. Turn the keyswitch to the ON position.

4. Start the engine and run the engine. Allow the engine coolant temperature to reach 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. This is done so that Cat ET will not reset.

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

6. Also check Cat ET for one of the following logged diagnostic codes or active diagnostic codes:
   • 320-02

   • 320-11

   • 342-02

   • 342-11

Expected Result:

None of the above codes are active or logged.

Results:

• OK - None of the codes are active or logged.

  Repair: Refer to the appropriate symptoms in Troubleshooting, "Troubleshooting Without a Diagnostic Code".

  STOP

• No Engine rpm - Engine rpm is not indicated on Cat ET during engine cranking. Proceed to Test Step 2.

• Active Code - One or more of the above codes are active or logged. Proceed to Test Step 4.

Test Step 2. Inspect the Sensor Assembly

Show/hide table



Illustration 2	g01155019
Engine speed/timing sensors (1) Bracket (2) Secondary speed/timing sensor (3) Mounting plate (4) O-ring seals (5) Bracket (6) Primary speed/timing sensor

1. Remove the suspect engine speed/timing sensor from the engine.

2. Ensure that O-ring seals (4) are installed on each sensor and on the mounting plate. Ensure that the O-ring seals are free of damage.

3. Ensure that mounting brackets are holding the sensor securely to the engine and that the brackets are not damaged or bent.

Expected Result:

All of the O-ring seals are properly installed and free of damage. The bracket is free of damage.

Results:

• OK - The O-ring seals are properly installed. The bracket is free of damage.

  Repair: Perform the following procedure in order to properly install a sensor assembly:

  1. Lubricate the O-ring seals with oil.

  2. Fully seat each 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.

  Proceed to Test Step 3.

• Not OK - At least one of the sensor assembly's components is not OK.

  Repair: 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 each O-ring 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 3. Inspect the Electrical Connectors and the Wiring

1. Turn the keyswitch to the OFF position.

Show/hide table



Illustration 3	g01150316
C12 engine speed/timing sensors (typical example) (7) J402/P402 connectors for the secondary engine speed/timing sensor (8) J401/P401 connectors for the primary engine speed/timing sensor (9) J2/P2 ECM connectors

Show/hide table



Illustration 4	g01150313
3406E, C15, and C18 engine speed/timing sensors (typical example) (7) J402/P402 connectors for the secondary engine speed/timing sensor (8) J401/P401 connectors for the primary engine speed/timing sensor (9) J2/P2 ECM connectors

2. Thoroughly inspect connectors (1), (2), and (3) .

Show/hide table



Illustration 5	g01150373
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 that are associated with the circuit for the engine speed/timing sensor.

4. Check the allen head screw on each ECM connector for the proper torque. 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 engine speed/timing sensors 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 4.

• 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 4. Measure the Sensor Resistance through the Engine Harness

1. Turn the keyswitch to the OFF position.

2. Disconnect the P2 connector at the ECM.

3. If you are troubleshooting a problem with the primary engine speed/timing sensor, perform the following procedure:

   1. Measure the sensor's resistance between P2-47 (Primary engine speed/timing +) and P2-48 (Primary engine speed/timing -).

      Resistance ... 110 to 220 Ohms

4. If you are troubleshooting a problem with the secondary engine speed/timing sensor, perform the following procedure:

   1. Measure the sensor's resistance between P2-58 (Secondary engine speed/timing +) and P2-59 (Secondary engine speed/timing -).

      Resistance ... 1000 to 1200 Ohms

Expected Result:

The resistance measurements are within the specifications.

Results:

• OK - The resistance measurements are within the specifications. The wiring appears to be OK. There could be a problem with the sensor or with the ECM. Proceed to Test Step 6.

• Not OK - At least one of the resistance measurements is not within the specifications. Proceed to Test Step 5.

Test Step 5. Measure the Resistance of the Sensor

1. Disconnect the engine harness from the suspect sensor.

2. For the primary engine speed/timing sensor, measure the resistance between J401-2 (Primary engine speed/timing +) to J401-1 (Primary engine speed/timing −).

   Resistance ... 110 to 200 Ohms

3. For the secondary engine speed/timing sensor, measure the resistance between J402-2 (secondary engine speed/timing +) to J402-1 (secondary engine speed/timing −).

   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. Proceed to Test Step 6.

Test Step 6. 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