3512B Marine Auxiliary Engine Caterpillar

The Engine Speed/Timing Sensors provide engine speed information to the engine's Electronic Control Modules (ECM). The sensors generate a pulse signal. A loss of both signals causes the ECM to stop sending power to the fuel injectors.

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 sensor should be repaired or replaced at the earliest possible convenience.

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 injector solenoids.

Illustration 1	g00602826

Note: The Engine Control Switch (ECS) is mounted within an instrument panel that is located on the right side of the engine. The ECS is locked into the AUTO position with a pin. The pin must be removed in order to perform this test. After performing this test, ensure that the ECS is placed in the AUTO position and that the locking pin has been reinstalled.

Test Step 1. Check for Connector Damage

1. Turn the circuit breaker for the battery to the OFF position.

2. Turn the ECS to the OFF/RESET position.

3. Disconnect the main power.

4. Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the other connectors. Refer to the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors" for details.

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

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

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

8. 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, of abrasion or of pinch points.

Results:

• OK - The connectors and wiring are okay. Proceed to test step 2.

• Not OK - The connectors and/or wiring need repair.

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

  Stop.

Test Step 2. Check for a CID-FMI.

1. Connect the Caterpillar Electronic Technician (ET).

2. Turn the circuit breaker for the battery to the ON position.

3. Turn the ECS to the STOP position.

4. Observe Logged Diagnostic Codes on the Cat ET.

Expected Result:

The Cat ET should indicate a CID-FMI 190-03 or 342-03.

Results:

• OK - The Cat ET indicates a CID-FMI 190-03 or 342-03. Proceed to test step 3.

• Not OK - The Cat ET does not indicate a CID-FMI 190-03 or 342-03. Proceed to test step 4.

Test Step 3. Check for Shorts in Wiring Harness

1. Turn the ECS to the OFF/RESET position.

2. Disconnect J1/P1 from the Primary ECM. Disconnect J1/P1 from the Secondary ECM. Disconnect the Primary Engine Speed/Timing Sensor J20/P20. Disconnect the Secondary Engine Speed/Timing Sensor J44/P44.

3. To test the Primary Engine Speed/Timing Sensor, measure the resistance at the Primary ECM connector P1:

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

   Measure the resistance between P1-38 and P1-30.

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

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

   Measure the resistance between P1-32 and P1-30.

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

   Measure the resistance between J20-A and engine ground.

   Measure the resistance between J20-B and engine ground.

   Measure the resistance between J20-C and engine ground.

4. To test the Secondary Engine Speed/Timing Sensor, measure the resistance at the Secondary ECM connector P1:

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

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

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

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

   Measure the resistance between J44-A and engine ground.

   Measure the resistance between J44-B and engine ground.

   Measure the resistance between J44-C and engine ground.

Expected Result:

The resistance should be greater than 20,000 Ohms.

Results:

• OK - The resistance is greater than 20,000 Ohms. Proceed to test step 5.

• Not OK - The resistance is less than 20,000 Ohms.

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

  Stop.

Test Step 4. Check the Engine Speed/Timing Sensor.

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NOTICE
Be sure to extend the sliphead before installing the Speed/Timing Sensor and also check that the Timing Gear is in a position that will not allow the sliphead of the Speed/Timing Sensor to protrude into the slot of the Timing Gear before the sensor is installed (visually inspect with a flashlight). 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. Turn the ECS to the OFF/RESET position.

2. Disconnect the sensor and remove the sensor.

3. Inspect the plastic sliphead for damage.

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

5. Extend the sliphead and reinstall the sensor.

   Note: If you are troubleshooting the Primary Engine Speed/Timing Sensor, disconnect the secondary sensor for the remainder of the test. If you are troubleshooting the Secondary Engine Speed/Timing Sensor, disconnect the primary sensor for the remainder of the test.

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

  Stop.

Test Step 5. Check the Resistance through the Harness.

1. Turn the ECS to the OFF/RESET position.

2. Disconnect J1/P1 from the Primary ECM. Disconnect J1/P1 from the Secondary ECM. Disconnect the Primary Engine Speed/Timing Sensor J20/P20. Disconnect the Secondary Engine Speed/Timing Sensor J44/P44.

3. For the Primary Engine Speed/Timing Sensor, perform the following steps.

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

5. Measure the resistance between P1-32 and P1-29. Wiggle the harness during the measurement in order to reveal an intermittent condition.

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

7. Measure the resistance between P1-32 and P1-38. Wiggle the harness during the measurement in order to reveal an intermittent condition.

8. For the Secondary Engine Speed/Timing Sensor, perform the following steps.

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

10. Measure the resistance between P1-32 and P1-29. Wiggle the harness during the measurement in order to reveal an intermittent condition.

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

12. Measure the resistance between P1-32 and P1-39. Wiggle the harness during the measurement in order to reveal an intermittent condition.

13. Measure the resistance between Primary ECM connector P1-38 and Secondary ECM connector P1-38. Wiggle the harness during the measurement in order to reveal an intermittent condition.

14. Measure the resistance between Primary ECM connector P1-39 and Secondary ECM connector P1-39. Wiggle the harness during the measurement in order to reveal an intermittent condition.

Expected Result:

The resistance should be less than 10 Ohms through the wires.

Results:

• OK - The resistance is less than 10 Ohms through the wires. Proceed to test step 11.

• Not OK - The resistance is greater than 10 Ohms through the wires. 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 6. Check the Engine Speed on the Cat ET.

1. Turn the ECS to the OFF/RESET position.

2. Reconnect all wiring and connectors.

3. Connect the Cat ET.

4. Start the engine.

5. Observe the engine speed on the Cat ET.

Expected Result:

The Cat ET should display a steady reading between 100 and 250 rpm. The engine should start.

Results:

• OK - The Engine Speed/Timing Sensor is operating correctly at this time.

  Repair: The problem may be intermittent. If the problem is intermittent, perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".

  Stop.

• ENGINE DOES NOT START - Engine speed appears on the Cat ET screen but the engine does not start.

  Repair: Refer to the diagnostic procedure Troubleshooting, "Engine Cranks but Will Not Start".

  Stop.

• NO ENGINE SPEED SIGNAL - The engine will not start and no engine speed signal appears on the Cat ET. Proceed to test step 7.

Test Step 7. Check the Supply Voltage at the ECM.

1. Turn the ECS to the STOP position.

2. Measure the voltage between P20-A and P20-B.

3. Measure the voltage between P44-A and P44-B.

4. Turn the ECS to the OFF/RESET position.

Expected Result:

The voltage should be 12.5 ± 1.0 VDC.

Results:

• OK - The voltage is 12.5 ± 1.0 VDC. Proceed to test step 8.

• Not OK - The voltage is not 12.5 ± 1.0 VDC. Proceed to test step 9.

Test Step 8. Check the Isolated Signal.

1. Remove pin-C from the sensor connector.

2. Turn the ECS to the STOP position.

3. Measure the voltage between pin-C and pin-B. Perform this step before you crank the engine. Perform this step while you are cranking the engine.

4. Turn the ECS to the OFF/RESET position.

5. Reinstall pin-C.

Expected Result:

With the ECS in the STOP position, the voltage should be less than 3.0 or the voltage should be greater than 10.0 VDC before you crank the engine. The voltage should be 2.0 to 7.0 VDC when you crank the engine.

Results:

• OK - With the ECS in the STOP position, the voltage is less than 3.0 or the voltage is greater than 10.0 VDC before you crank the engine. The voltage is 2.0 to 7.0 VDC when you crank the engine. Proceed to test step 3.

• Not OK - With the ECS in the STOP position, the voltage is not less than 3.0 or the voltage is not greater than 10.0 VDC before you crank the engine. The voltage is not 2.0 to 7.0 VDC when you crank the engine.

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

  Stop.

Test Step 9. Check the Supply Voltage at the Sensor Connector.

1. Measure voltage between J20-A and J20-B.

2. Measure voltage between J44-A and J44-B.

Expected Result:

The voltage should be 12.5 ± 1.0 VDC.

Results:

• OK - The voltage is 12.5 ± 1.0 VDC. There is an open circuit 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 12.5 ± 1.0 VDC. Proceed to test step 10.

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

1. Measure the voltage at the Primary ECM connector between P1-32 and P1-29. Measure the voltage at the Secondary ECM connector between P1-32 and P1-29.

Expected Result:

The voltage should be 12.5 ± 1.0 VDC.

Results:

• OK - There is an open circuit 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 - 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 Signal Voltage at the ECM.

1. Turn the ECS to the STOP position.

2. Measure the voltage between P1-38 and P1-29 for the Primary Engine Speed/Timing Sensor. Measure the voltage before you crank the engine and while you crank the engine.

3. Measure the voltage between P1-39 and P1-29 for the Secondary Engine Speed/Timing Sensor. Measure the voltage before you crank the engine and while you crank the engine.

   Turn the ECS to the OFF/RESET position.

Expected Result:

With the ECS in the STOP position, the voltage should be less than 3.0 or the voltage should be greater than 10.0 VDC before you crank the engine. The voltage should be 2.0 to 7.0 VDC when you crank the engine.

Results:

• OK - With the ECS in the STOP position, the voltage is less than 3.0 or the voltage is greater than 10.0 VDC before you crank the engine. The voltage is 2.0 to 7.0 VDC when you crank the engine. Proceed to test step 12.

• Not OK - The sensor signal is not reaching the ECM. Recheck the harness and connectors for shorts or excessive resistance.

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

  Stop.

Test Step 12. Check the Engine Speed.

1. Turn the ECS to the STOP position.

2. 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 Cat ET displays a steady engine speed between 100 and 250 rpm while the engine is cranking. The sensor is operating correctly at this time.

  Repair: The problem may be intermittent. If the problem is intermittent, perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".

  Stop.

• Not OK - A valid signal appears at the P1 but the ECM is not reading the signal properly.

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

  Stop.