3512B Petroleum Engines with the ADEM 2 Electronic Control Module 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 Electronic Control Module (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 injection. The loss of the primary timing signal from the 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 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 injectors.

Illustration 1	g00820920

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

1. Start the Cat ET.

2. Turn the engine control 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 the Electrical Connectors and the Wiring.

1. Turn the engine control 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:

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

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 wiring and connectors or replace the wiring or the connectors. Ensure that all of the seals are properly connected. Verify that the repair eliminates the problem.

  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 through the wires.

Results:

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

• Not OK - The resistance is greater than 10 Ohms. 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.

Show/hide table

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:

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

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 diagnostic calibration procedure Troubleshooting, "Engine Speed/Timing Sensor - Calibrate".

  STOP

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

1. Start the Cat ET.

2. Turn the engine control to the ON position.

3. Start the engine.

4. Observe the engine speed on the status screen of the Cat ET 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 status 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 status 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 engine control to the OFF position.

2. Disconnect the Engine Speed/Timing Sensor.

3. Turn the engine control to the ON position.

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

5. Turn the engine control 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 9.

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

1. Turn the engine control to the OFF position.

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

3. Turn the engine control to the ON position.

4. Measure the voltage between the wire from pin-C and socket B of the Engine Speed/Timing Sensor. Perform this step before you crank the engine and when you crank the engine.

5. Turn the engine control 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. Proceed to test step 10.

• Not OK - The voltage is incorrect.

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

  STOP

Test Step 9. Check the Supply Voltage at the ECM.

1. Turn the engine control to the OFF position.

2. Remove the voltage supply wire 996-GN from ECM connector P1-32. Install a wire jumper into the socket for P1-32.

3. Turn the engine control to the ON position.

4. Measure the voltage between the wire jumper and the digital return P1-29 of the ECM connector P1.

5. Turn the engine control to the OFF position.

6. Remove the wire jumper. Reconnect all wires and connectors.

Expected Result:

The voltage should be 13 ± 1.0 VDC.

Results:

• OK - The voltage is 13 ± 1.0 VDC.

  Repair: There is a problem in the harness between the ECM and the sensor. 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 10. Check the Isolated Signal Voltage at the ECM.

1. Turn the engine control to the OFF position.

2. Remove the signal wire P1-38 from the ECM connector P1 if you are working on the Primary Engine Speed/Timing Sensor.

3. Remove the signal wire P1-39 from the ECM connector P1 if you are working on the Secondary Engine Speed/Timing Sensor.

4. Turn the engine control to the ON position.

5. Measure the voltage between P1-38 and the digital return P1-29 of the ECM connector P1. Measure the voltage before you crank the engine and while you crank the engine.

6. Measure the voltage between P1-39 and the digital return P1-29 of the ECM connector P1. Measure the voltage before you crank the engine and while you crank the engine.

7. Turn the engine control 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.

  Repair: The ECM is not reading the signal correctly. Check the connectors for any problems. If there are no problems with the connector replace the ECM. Perform the diagnostic procedure Troubleshooting, "Replacing the ECM".

  STOP

• Not OK - The voltage is incorrect.

  Repair: There is a problem in the harness between the ECM and the sensor. Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP