3512B Engine for SPF343, SPS343, and SPT343 Pumpers Caterpillar

The Electronic Control Module (ECM) provides the Engine Speed/Timing Sensor with a supply voltage of 13 ± 1.0 VDC. The Engine Speed/Timing Sensor provides a pulse signal to the ECM. The signal is created as the timing reference gear rotates past the pickup of the Engine Speed/Timing Sensor. The timing reference gear is mounted on the rear of the left camshaft. A unique tooth pattern on the timing reference gear allows the ECM to determine the crankshaft position, engine rotation, and engine rpm.

If the primary Engine Speed/Timing Sensor fails, the ECM will use the secondary Engine Speed/Timing Sensor until electrical power is removed from the ECM. To prevent any unnecessary down time, the primary Engine Speed/Timing Sensor should be repaired or replaced at the earliest possible convenience.

The Engine Speed/Timing Sensor generates a pulse signal to the ECM as each tooth passes the sensor. The ECM counts the pulses in order to determine the engine rpm. The ECM memorizes the pattern of the pulses. The ECM compares that pattern to a standard pattern that is stored in memory in order to determine the crankshaft position. The ECM uses this information to determine the No. 1 cylinder. The ECM then triggers each fuel injector to fire in the correct firing order and at the correct time. The actual timing and duration of each injection is determined by the ECM. The ECM uses engine rpm and engine load to determine the timing and duration of the fuel injection. The loss of the primary timing signal from the primary Engine Speed/Timing Sensor generates an alert on the status screen of the Caterpillar Electronic Technician (ET). The loss of the secondary timing signal from the secondary Engine Speed/Timing Sensor triggers the termination of the signals to the fuel injectors.

Note: If the ring gear is reversed, the diagnostic codes 190-08 and 342-08 will be generated and the ECM will not fire the fuel injectors.

Illustration 1	g00855101
Typical example

Test Step 1. Check for "ACTIVE" Diagnostic Codes.

1. Start the Cat ET.

2. Turn the circuit breaker CB-8 to the ON position.

3. Monitor the active diagnostic codes on the Cat ET.

Expected Result:

Any of the following diagnostic codes are active:

• CID-FMI 190-02 Loss of Engine Speed signal

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

• CID-FMI 190-07 Primary Speed Sensor misinstalled

• CID-FMI 342-02 Loss of Secondary Engine Speed signal

• CID-FMI 342-07 Secondary Speed Sensor misinstalled

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

Results:

• OK - Either a CID-FMI 190-03 Engine Speed open/short to +batt diagnostic code or a CID-FMI 342-03 Secondary Engine Speed open/short to +batt diagnostic code is active. Proceed to test step 2.

• OK - A CID-FMI 190-07 Primary Speed Sensor misinstalled diagnostic code or a CID-FMI 342-07 Secondary Speed Sensor misinstalled diagnostic code is active.

  Repair: Switch the primary Engine Speed/Timing Sensor and the secondary Engine Speed/Timing Sensor. Verify that the problem is no longer present.

  Stop.

• OK - A CID-FMI 190-02 Loss of Engine Speed signal diagnostic code or a CID-FMI 342-02 Loss of Secondary Engine Speed signal diagnostic code is present. Proceed to test step 5.

Test Step 2. Check for Connector Damage.

1. Turn the circuit breaker CB-8 to the OFF position.

2. Thoroughly inspect the ECM connector J1/P1. Inspect all of the other connectors. Refer to the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors" for details.

3. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.

4. Check the ECM connector (allen head screw) for the proper torque of 6.0 N·m (55 lb in).

5. Check the customer connector (allen head screw) for the proper torque of 2.25 ± 0.25 N·m (20 ± 2 lb in).

6. Check the harness and the wiring for abrasion and pinch points.

Expected Result:

The connectors and wiring should be free of the following problems: damage, corrosion, abrasion and incorrect attachment.

Results:

• OK - The wiring and connectors are okay. Proceed to Test Step 3.

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

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  Stop.

Test Step 3. Check for a Short Circuit in the Wiring Harness.

1. Disconnect J1/P1 from the ECM. Disconnect the primary Engine Speed/Timing Sensor J20/P20. Disconnect the secondary Engine Speed/Timing Sensor J44/P44.

2. Measure the resistance between P1-38 and P1-29.

3. Measure the resistance between P1-38 and P1-32.

4. Measure the resistance between P1-32 and P1-29.

5. Measure the resistance between P1-39 and P1-29.

6. Measure the resistance between P1-39 and P1-32.

7. Measure the resistance between J20-A and the engine ground.

8. Measure the resistance between J20-B and the engine ground.

9. Measure the resistance between J20-C and the engine ground.

10. Measure the resistance between J44-A and the engine ground.

11. Measure the resistance between J44-B and the engine ground.

12. Measure the resistance between J44-C and the engine ground.

Expected Result:

The resistance should be greater than 20,000 Ohms for each measurement.

Results:

• OK - The resistance is greater than 20,000 Ohms. Proceed to test step 4.

• Not OK - The resistance is less than 20,000 Ohms. There is a short circuit in the harness or connectors.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  Stop.

Test Step 4. Check for an Open Circuit in the Wiring Harness.

1. Use a suitable piece of wire to short J44-A and J44-B together.

2. Measure the resistance between P1-32 and P1-29.

3. Use a suitable piece of wire to short J44-B and J44-C together.

4. Measure the resistance between P1-29 and P1-39.

5. Use a suitable piece of wire to short J44-C and J44-A together.

6. Measure the resistance between P1-39 and P1-32.

7. Use a suitable piece of wire to short J20-A and J20-B.

8. Measure the resistance between P1-32 and P1-29.

9. Use a suitable piece of wire to short J20-B and J20-C.

10. Measure the resistance between P1-29 and P1-38.

11. Use a suitable piece of wire to short J20-C and J20-A.

12. Measure the resistance between P1-38 and P1-32.

13. Remove all shorts and reconnect J1/P1, J44/P44, and J20/P20.

Expected Result:

The resistance should be less than 10 Ohms for each measurement.

Results:

• OK - The resistance is less than 10 Ohms for each measurement. The harness resistance is within acceptable limits. Proceed to test step 6.

• Not OK - The resistance is greater than 10 Ohms for one or more measurements. There is an open circuit or excessive resistance in the harness or connectors.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  Stop.

Test Step 5. Check the Engine Speed/Timing Sensor.

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NOTICE
Be sure to extend the sliphead before installing the Engine Speed/Timing Sensor. Also check that the Timing Gear is in a position that will not allow the sliphead of the Engine Speed/Timing Sensor to protrude into one of the slots of the Timing Gear. This is done visually with a flashlight prior to the installation of the Engine Speed/Timing Sensor. Turn the crankshaft to rotate the Timing Gear, if necessary, to position the gear in a place that will not allow the sliphead to protrude into a slot. If the sensor sliphead does protrude into one of the slots, the sliphead will be broken off as the gear begins to rotate.

1. Remove the suspect Engine Speed/Timing Sensor.

2. Inspect the plastic sliphead for damage.

3. Check the tension. Gently extend the sliphead 3.5 mm (0.14 inch). Return the sliphead to the original position.

4. Extend the sliphead.

5. Install the Engine Speed/Timing Sensor.

Expected Result:

Pushing in the sliphead from the extended position should take at least 22 N (5 lb) of force.

Results:

• OK - The Engine Speed/Timing Sensor and the sliphead are undamaged. The tension on the sliphead is normal. Reinstall the sensor. Proceed to test step 6.

• Not OK - The Engine Speed/Timing Sensor or the sliphead is damaged, or the sliphead has insufficient tension.

  Repair: Replace the Engine Speed/Timing Sensor. Calibrate the sensor. Perform the calibration procedure Troubleshooting, "Engine Speed/Timing Sensor - Calibrate".

  Stop.

Test Step 6. Check the Engine Speed on the Cat ET.

1. Start the Cat ET.

2. Turn the circuit breaker CB-8 to the ON position.

3. Start the engine.

4. Observe the engine speed on the Cat ET screen while you crank the engine.

Expected Result:

The Cat ET should display 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: There may be an intermittent problem. Perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors" if the problem is intermittent.

  Stop.

• Not OK - The Cat ET screen does not display a steady engine speed between 100 and 250 rpm while the engine is cranking. Proceed to test step 7.

• Intermittent Problem - The Cat ET screen displays an erratic engine rpm.

  Repair: Perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".

  Stop.

Test Step 7. Check the Supply Voltage at the Sensor Connector.

1. Turn the circuit breaker CB-8 to the OFF position.

2. Disconnect the Engine Speed/Timing Sensor at connector J20/P20 or connector J44/P44.

3. Turn the circuit breaker CB-8 to the ON position.

4. Measure the voltage between socket A and socket B at the connector for the Engine Speed/Timing Sensor.

5. Turn the circuit breaker CB-8 to the OFF position.

6. Reconnect the sensor connector.

Expected Result:

The supply voltage should be 13 ± 1.0 VDC.

Results:

• OK - The supply voltage is 13 ± 1.0 VDC. The sensor is receiving the correct supply voltage. Proceed to test step 8.

• Not OK - The supply voltage is not 13 ± 1.0 VDC. Proceed to test step 10.

Test Step 8. Check the Isolated Signal Voltage at the ECM.

1. Turn the circuit breaker CB-8 to the OFF position.

2. Remove the signal wire P1-38 for the primary Engine Speed/Timing Sensor from ECM connector P1.

3. Remove the signal wire P1-39 for the secondary Engine Speed/Timing Sensor from ECM connector P1.

4. Turn the circuit breaker CB-8 to the ON position.

5. Measure the voltage between P1-38 and P1-29. Measure the voltage before you crank the engine and while you crank the engine.

6. Measure the voltage between P1-39 and P1-29. Measure the voltage before you crank the engine and while you crank the engine.

7. Turn the Battery switch for the ECM to the OFF position.

8. Reinstall all wires and reconnect all connectors.

Expected Result:

The voltage should be less than 3 VDC or more than 9 VDC when the power is ON and the engine is not cranking. While the engine is cranking, the voltage should be between 2 VDC and 7 VDC.

Results:

• OK - The voltage is correct. Proceed to test step 9.

• Not OK - The voltage is incorrect. Proceed to test step 11.

Test Step 9. Recheck the Engine Speed on the Cat ET.

1. Start the Cat ET.

2. Turn the circuit breaker CB-8 to the ON position.

3. Start the engine.

4. Observe the engine speed on the Cat ET screen while you crank the engine.

Expected Result:

The Cat ET screen should display a steady engine speed between 100 and 250 rpm while the engine is cranking.

Results:

• OK - The Cat ET screen displays a steady engine speed between 100 and 250 rpm while the engine is cranking. The Engine Speed/Timing Sensor is operating normally at this time.

  Repair: There may be an intermittent problem in the engine speed/timing circuit. Perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors" if the problem is intermittent.

  Stop.

• Not OK - The correct voltage signal appears at the ECM connector J1/P1 but the ECM is not reading the signal.

  Repair: Replace the ECM. Perform the diagnostic procedure Troubleshooting, "Replacing the ECM".

  Stop.

Test Step 10. Check the Supply Voltage at the ECM.

1. Turn the circuit breaker CB-8 to the OFF position.

2. Remove the supply wire P1-32 for the Engine Speed/Timing Sensor from ECM connector P1. Install a wire jumper into the socket for P1-32.

3. Remove the digital return wire P1-29 from ECM connector P1. Install a wire jumper into the socket for P1-29.

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

4. Turn the circuit breaker CB-8 to the ON position.

5. Measure the voltage between the wire jumpers in P1-32 and P1-29.

6. Turn the circuit breaker CB-8 to the OFF position.

7. Reconnect all connectors.

Expected Result:

The voltage should be 13 ± 1.0 VDC.

Results:

• OK - The voltage is 13 ± 1.0 VDC. There is a problem in the harness between the ECM and the sensor.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  Stop.

• Not OK - The voltage is not 13 ± 1.0 VDC. Check that the ECM is receiving the correct supply voltage.

  Repair: Perform the diagnostic functional test Troubleshooting, "Electrical Power Supply".

  Stop.

Test Step 11. Check the Isolated Signal Voltage at the Sensor.

1. Turn the circuit breaker CB-8 to the OFF position.

2. Remove the wire at pin-C from either P20 or P44.

3. Turn the circuit breaker CB-8 to the ON position.

4. Measure the voltage between the wire and pin B of either P20 or P44. Perform this step before you crank the engine and when you crank the engine.

5. Turn the circuit breaker CB-8 to the OFF position.

6. Reinstall all wires and reconnect all connectors.

Expected Result:

The voltage should be less than 3 VDC or more than 9 VDC when the power is ON and the engine is not cranking. While the engine is cranking, the voltage should be between 2 VDC and 7 VDC.

Results:

• OK - The voltage is correct.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring between the sensor connector and the ECM.

  Stop.

• Not OK - The voltage is incorrect.

  Repair: Replace the Engine Speed/Timing Sensor. Calibrate the sensor. Perform the calibration procedure Troubleshooting, "Engine Speed/Timing Sensor - Calibrate".

  Stop.