3412E Petroleum Engine 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:

• 190-02 Loss of Engine Speed Signal

• 190-03 Engine Speed open/short to +batt

• 190-08 Engine Speed abnormal

• 342-02 Loss of Secondary Engine Speed signal

• 342-03 Secondary Engine Speed open/short to +batt

• 342-08 Secondary Engine Speed signal abnormal

The engine uses two engine speed/timing sensors. Both sensors detect the reference for engine speed and timing from a timing reference ring with a unique pattern that is on the rear face of the fuel injection pump gear. The Electronic Control Module (ECM) uses the pattern of the pulses in order to determine the position of the crankshaft. The ECM measures the time between the pulses that are created by the sensors as the gears rotate in order to determine rpm.

Under normal operation, the primary speed/timing sensor determines when the piston in the No. 1 cylinder is at the top of the compression stroke. When the timing has been established, the sensor signal is 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 engine rpm and on load.

The secondary speed/timing sensor provides continuous operation of the engine if the primary engine speed/timing sensor fails. If the engine is running and the signal from one sensor is lost, no 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.

The engine speed/timing sensors receive supply voltage from the ECM that is regulated at 12.5 ± 1.0 VDC. The engine speed/timing sensors provide a pulsed DC output voltage with a frequency that is directly proportional to engine speed. A unique tooth on the timing reference ring generates a duty cycle in order to provide the ECM with information on the crankshaft position.

Illustration 1	g01137012
Schematic for the engine speed/timing sensors

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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.

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Illustration 2	g01137151
Top engine view (1) Timing calibration probe connector (2) P1/J1 ECM connector (3) Primary engine speed/timing sensor (4) Secondary engine speed/timing sensor

2. Thoroughly inspect connectors (1) and (2) .,Also inspect the connectors for speed/timing sensors (3) and (4). Refer to Troubleshooting, "Electrical Connectors - Inspect".

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Illustration 3	g01137168
P1 ECM connector (P1-29) Digital return (P1-32) Speed/timing sensor supply (P1-38) Primary speed/timing sensor signal (P1-39) Secondary speed/timing sensor signal

3. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the engine speed/timing sensors.

4. Check the torque of the allen head screws for the ECM connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque value.

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

Expected Result:

All of the 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 in good repair. Proceed to Test Step 2.

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

  Repair: Repair the wiring and/or the connectors. Replace parts, if necessary. 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 Diagnostic Codes

1. Connect the Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".

2. Turn the keyswitch to the ON position.

3. Check for active diagnostic codes on Cat ET.

   Look for these codes:

   • 190-02

   • 190-03

   • 190-08

   • 342-02

   • 342-03

   • 342-08

Expected Result:

None of the above diagnostic codes are active.

Results:

• OK - None of the above codes are active, but there is a problem that has been associated with the engine speed/timing sensors. Proceed to Test Step 4.

• 190-02 and/or 190-08 is Active - The signal for the primary engine speed/timing sensor is lost or abnormal. Proceed to Test Step 3.

• 190-03 is Active - There may be a problem with the wiring harness for the primary engine speed/timing sensor. Proceed to Test Step 7.

• 342-02 and/or 342-08 is Active - The signal for the secondary engine speed/timing sensor is lost or abnormal. Proceed to Test Step 3.

• 342-03 is Active - There may be a problem with the wiring harness for the secondary engine speed/timing sensor. Proceed to Test Step 7.

Test Step 3. Inspect the Condition of the Engine Speed/Timing Sensors

1. Turn the keyswitch to the OFF position.

2. Remove the suspect engine speed/timing sensor.

3. Inspect the plastic sliphead for damage.

4. Check the tension on the sliphead by gently prying the sliphead out of the sensor body. Extend the sliphead 3 to 4 mm (0.12 to 0.16 inch). Push the sliphead back into the sensor body from the extended position. Movement of the sliphead will require a small amount of force. The amount of tension that is on the sliphead must not allow movement of the sliphead during engine operation.

5. Again, pull the sliphead from the sensor body to the fully extended position.

Expected Result:

The sensor is not damaged. An adequate amount of tension is felt on the sliphead and the movement is smooth.

Results:

• OK - The engine speed/timing sensor and the sliphead are undamaged. The tension on the sliphead is normal.

  Repair: Reinstall the engine speed/timing sensor. Ensure that the camshaft gear is positioned correctly prior to installing the sensor.

  Proceed to Test Step 4.

• Not OK - The engine speed/timing sensor or the sliphead has insufficient tension, or the sliphead is damaged.

  Repair: Replace the speed/timing sensor that is damaged. Refer to Disassembly and Assembly, "Speed/Timing Sensor - Remove and Install" prior to installing the new sensor.Calibrate the new sensor. Refer to Troubleshooting, "Engine Speed/Timing Sensor - Calibrate". Verify that the repair eliminates the problem.

  STOP

Test Step 4. Check the Engine Speed on Caterpillar Electronic Technician (ET)

1. Turn the keyswitch to the ON position and crank the engine.

2. Observe the engine speed on Cat ET while the engine is cranking.

Expected Result:

Cat ET displays a steady engine speed between 100 and 250 rpm while the engine is cranking and the engine starts.

Results:

• OK - The engine speed/timing sensor is operating normally at this time.

  Repair: Reconnect the known good engine speed/timing sensor.If you are troubleshooting an intermittent problem, refer to Troubleshooting, "Electrical Connectors - Inspect".

  STOP

• Not OK - Cat ET displays zero engine speed and the engine does not start. Proceed to Test Step 5.

• Not OK - Cat ET displays a steady engine speed, but the engine will not start.

  Repair: Reconnect the known good engine speed/timing sensor.Proceed to Troubleshooting, "Engine Cranks But Will Not Start".

  STOP

Test Step 5. Check the Supply Voltage at the Sensor Connector

1. Install a 3-pin breakout at the connector for the suspect engine speed/timing sensor.

2. Turn the keyswitch to the ON position.

3. Measure the voltage between terminal A (speed/timing sensor supply) and terminal B (digital return) of the breakout.

4. Turn the keyswitch to the OFF position.

Expected Result:

The supply voltage is measured at 11.5 to 13.5 VDC at the sensor connector.

Results:

• OK - The engine speed/timing sensor is receiving the correct supply voltage. Proceed to Test Step 6.

• Not OK - The supply voltage is not within the specified range. Proceed to Test Step 7.

Test Step 6. Check the Isolated Signal Voltage at the Sensor

1. Remove the wire from terminal C (speed/timing sensor signal) at the harness side of the connector for the suspect speed/timing sensor.

2. Measure the voltage between terminal B (digital return) and terminal C (speed/timing sensor signal) of the breakout with the keyswitch in the ON position. Also measure this voltage while the engine is cranking.

3. Turn the keyswitch to the OFF position.

4. Return the wiring for the sensor connectors to the original configuration.

Expected Result:

The voltage is less than 3.0 VDC or the voltage is greater than 10.0 VDC with the keyswitch in the ON position. The voltage varies between 2.0 VDC and 4.0 VDC during engine cranking.

Results:

• OK - The engine speed/timing sensor is producing an output signal. Proceed to Test Step 8.

• Not OK - The engine speed/timing sensor is not producing a valid output signal.

  Repair: Replace the engine speed/timing sensor. Refer to Disassembly and Assembly, "Speed/Timing Sensor - Remove and Install" prior to installing the new sensor.Calibrate the new sensor. Refer to Troubleshooting, "Engine Speed/Timing Sensor - Calibrate". Verify that the repair eliminates the problem.

  STOP

Test Step 7. Check the Supply Voltage at the ECM

1. Turn the keyswitch to the OFF position.

2. Install a 40-pin breakout at the J1/P1 ECM connector.

3. Turn the keyswitch to the ON position.

4. Measure the voltage between P1-29 digital return and P1-32 engine speed/timing signal at the breakout.

5. Turn the keyswitch to the OFF position.

Expected Result:

The voltage is 12.5 ± 1.0 VDC.

Results:

• OK - The supply voltage is present at the ECM, but not present at the sensor connector. There is an open circuit or excessive resistance in the harness between the ECM and the sensor.

  Repair: Repair the wiring and/or the connectors. Replace parts, if necessary. 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

• Not OK -

  Repair: Ensure that the ECM is receiving the correct supply voltage from the batteries. Refer to Troubleshooting, "Electrical Power Supply Circuit - Test".

  If the ECM is receiving the correct supply voltage, proceed to Test Step 8.

Test Step 8. Check for a Short Circuit in the Wiring Harness

1. Turn the keyswitch to the OFF position.

2. Disconnect the J1/P1 ECM connector and the connector for the suspect engine speed/timing sensor.

3. Measure the following resistances on the harness side of the connector for the suspect speed/timing sensor.
   • Terminal A (speed/timing sensor supply) and terminal B (digital return)

   • Terminal A (speed/timing sensor supply) and terminal C (speed/timing sensor signal)

   • Terminal B (digital return) and terminal C (speed/timing sensor signal)

   • Terminal A (speed/timing sensor supply) and engine ground

   • Terminal B (digital return) and engine ground

   • Terminal C (speed/timing sensor signal) and engine ground

Expected Result:

An open circuit has been detected for all resistances that were measured.

Results:

• OK - Proceed to Test Step 9.

• Not OK - There is a short circuit in the harness or in the connectors.

  Repair: Repair the wiring and/or the connectors. Replace parts, if necessary. 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 9. Check the Resistance through the Harness

1. Fabricate a jumper wire. Crimp a terminal onto both ends of the jumper wire.

2. Install the wire into terminal P1-32 (speed/timing sensor supply) and terminal P1-29 (digital return) together.

3. Measure the resistance between terminal J20-A (speed/timing sensor supply) and terminal J20-B (digital return).

4. Measure the resistance between terminals J44-A (speed/timing sensor supply) and J44-B (digital return).

5. Use the jumper wire to short terminal P1-32 (speed/timing sensor supply) and terminal P1-38 (primary speed/timing sensor signal).

6. Measure the resistance between terminal J20-A (speed/timing sensor supply) and terminal J20-C (primary speed/timing sensor signal).

7. Use the jumper wire to short terminal P1-32 (speed/timing sensor supply) and P1-39 (speed/timing sensor signal).

8. Measure the resistance between terminals J44-A (speed/timing sensor supply) and J44-C (secondary speed/timing sensor signal).

9. Remove the jumper wire and restore the wiring for the sensor connectors to the original configuration.

Expected Result:

The resistance reads less than 10 Ohms for all measurements.

Results:

• OK - The harness resistances are within acceptable limits. Proceed to Test Step 10.

• Not OK - There is an open circuit or excessive resistance in the harness or connectors. There may be a problem with a connector.

  Repair: Repair the wiring and/or the connector. Replace parts, if necessary. Verify that the problem is resolved.

  STOP

Test Step 10. Check the Signal Voltage at the ECM

1. Install a 40-pin breakout at the J1/P1 ECM connector.

2. Turn the keyswitch to the ON position.

3. Measure the signal voltage at the breakout, as follows:

   Primary Engine Speed/Timing Sensor

   Measure the voltage between terminal P1-38 (primary speed/timing sensor signal) and terminal P1-29 (digital return) at the breakout. Perform this step with the keyswitch in the ON position before you crank the engine and while you crank the engine.

   Secondary Engine Speed/Timing Sensor

   Measure the voltage between terminal P1-39 (secondary speed/timing sensor signal) and terminal P1-29 (digital return) at the breakout. Perform this step with the keyswitch in the ON position before you crank the engine and while you crank the engine.

4. Turn the keyswitch to the OFF position.

Expected Result:

The voltage is less than 3.0 VDC or the voltage is greater than 10.0 VDC with the keyswitch in the ON position. The voltage varies between 2.0 VDC and 4.0 VDC during engine cranking.

Results:

• OK - The engine speed/timing signal is reaching the ECM connector. Proceed to Test Step 11.

• Not OK - The engine speed/timing signal is not reaching the ECM.

  Repair: Recheck the harness and connectors for shorts, opens, or excessive resistance. Repair the wiring and/or the connector. Replace parts, if necessary. Verify that the problem is resolved.

  STOP

Test Step 11. Check Engine Speed on Cat ET

1. Turn the keyswitch to the ON position and crank the engine.

2. Observe the engine speed on Cat ET while you crank the engine.

Expected Result:

Cat ET displays a steady engine speed between 100 and 250 rpm while the engine is cranking.

Results:

• OK - The engine speed/timing sensor is operating normally at this time.

  Repair: Reconnect the known good engine speed/timing sensor.Refer to Troubleshooting, "Electrical Connectors - Inspect" if you are troubleshooting an intermittent problem.

  STOP

• NOT OK - A valid engine speed/timing signal appears at ECM connector P1, but the ECM is not reading the signal properly.

  Repair: Replace the ECM. Refer to Troubleshooting, "Replacing the ECM" before replacing the ECM.

  STOP