3500B Marine Engines Caterpillar

The Engine Speed/Timing Sensors provide engine speed information to the Electronic Control Module (ECM). The sensor generates 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.

The Electronic Control Module (ECM) provides the Engine Speed/Timing Sensor with 12.5 ± 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, rotation, and rpm.

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

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. 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.

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

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

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

7. Check the harness and the wiring for abrasion and for 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 indicates 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 indicates a CID-FMI 190-02 or 190-08. The Cat ET indicates a CID-FMI 342-02 or 342-08. 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 P1-32.

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

   Measure the resistance between P1-38 and engine ground.

   Measure the resistance between P1-32 and engine ground.

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

   Measure the resistance between P1-32 and engine ground.

   Measure the resistance between P1-29 and engine ground.

Expected Result:

The resistance should be greater than 20,000 Ohm.

Results:

• OK - The resistance is greater than 20,000 Ohm. Proceed to Test Step 5.

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

  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 in order 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 following diagnostic functional test Troubleshooting, "Engine Speed/Timing Sensor - Calibrate".

  STOP

Test Step 5. Check for an Open in the Harness.

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

2. For the primary Engine Speed/Timing Sensor, perform the following steps.

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

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

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

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

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

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

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

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

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

4. Measure the resistance between the primary ECM connector P1-38 and the secondary ECM connector P1-38. Wiggle the harness during the measurement in order to reveal an intermittent condition.

5. Measure the resistance between the primary ECM connector P1-39 and the 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 5 Ohms through the wires.

Results:

• OK - The resistance is less than 5 Ohms through the wires. Proceed to Test Step 11.

• Not OK - The resistance is greater than 5 Ohms through the wires. There is an open circuit 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.

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

2. Connect the Cat ET.

3. Crank the engine.

4. Observe the engine speed on the Cat ET screen.

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 screen. Proceed to Test Step 7.

Test Step 7. Check the Supply Voltage on the Sensor Side of the Sensor Connector.

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 from the Sensor at the Sensor Connector.

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 11.

• 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 diagnostic functional test Troubleshooting, "Engine Speed/Timing Sensor - Calibrate".

  STOP

Test Step 9. Check the Supply Voltage on the ECM Side of 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. The connector for the sensor is damaged.

  Repair: Repair the connector or replace the connector.

  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 following diagnostic procedure 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 ECM connector but the ECM is not reading the signal properly.

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

  STOP