3500B and 3500B High Displacement Generator Set Engines Caterpillar

The Electronic Control Module (ECM) has the ability to crank the engine when the Engine Control Switch (ECS) is placed in the LOCAL position. When the ECS is placed in the LOCAL position, the ECM will activate the prelube system. Refer to Troubleshooting, "Prelubrication System". The engine control will start the first crank cycle when the prelube is completed. The crank cycle continues for the programmed time or the engine speed reaches the crank terminate speed. If crank terminate speed is not reached before reaching the cycle crank time, the starting motor will deactivate for a time that is equal to the cycle crank time.

This process will repeat for a programmed amount of times (Total Number of Crank Cycles). If the engine does not start the starter mode on the Caterpillar Electronic Technician (ET) will display "OVERCRANK". The engine control will be in an idle state. The crank cycle can be restarted by turning the ECS to the OFF and then turning the ECS to the LOCAL position.

Note: When the starting motor fails to engage the flywheel due to a Butt engagement, that crank cycle will still be counted in the total number of crank cycles.

Illustration 1	g01024175
Typical circuit with EMS II

Test Step 1. Check for Connector Damage.

1. Turn the ECS to the OFF position.

2. Turn the battery disconnect switch to the OFF 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 6.0 N·m (55 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 pinch points.

Expected Result:

All connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring are 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. Attempt to Start the Engine

1. Connect Cat ET to the service tool connector J60/P60.

2. Turn the battery disconnect switch to the ON position.

3. Turn the ECS to the STOP position.

4. Observe the "startup mode" parameters on the Cat ET status screen.

5. Turn the ECS to the LOCAL position. Continue monitoring engine parameters as the engine cranks.

6. The crank cycle will continue for the time that is equal to the cycle crank time that has been programmed or the crank cycle will continue until the engine speed reaches the crank terminate speed.

7. Turn the ECS to the OFF position.

Expected Result:

The status screen for the "startup mode" parameter displays "CRANK". The engine cranks.

Results:

• OK - The "startup mode" parameter on the status screen on Cat ET displays "CRANK". The engine cranks.

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

  Stop.

• Not OK - Engine Doesn't Crank - The "startup mode" parameter on the status screen on Cat ET displays "CRANK". The engine will not crank. Proceed to Test Step 3.

• Not OK - Status Screen - The "startup mode" parameter on the status screen on Cat ET does not display "CRANK".

  Repair: Perform the diagnostic functional test Troubleshooting, "Engine Control Switch (ECS)".

  Stop.

Test Step 3. Check the Voltage from the Starting Motor Relay.

1. Turn the battery disconnect switch to the OFF position.

2. Open the power distribution box that is located on the left side of the engine, close to the starter motors.

3. Connect one probe of a digital voltmeter to the -Battery terminal. Connect the other probe of the digital voltmeter to wire 314-PU on terminal 2 of the starting motor relay.

4. Turn the battery disconnect switch to the ON position.

5. Turn the ECS to the LOCAL position.

6. Monitor the voltage on the digital voltmeter.

7. Turn the ECS to the OFF position.

Expected Result:

The voltage measures 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC. Proceed to Test Step 8.

• Not OK - The voltage does not measure 24 ± 3 VDC. Proceed to Test Step 4.

Test Step 4. Check the Coil on the Starting Motor Relay.

1. Turn the battery disconnect switch to the OFF position.

2. Connect one probe of the digital voltmeter to terminal 3 of the starting motor relay. Connect the other probe of the digital voltmeter to wire 200-BK on terminal 4 of the starting motor relay.

3. Turn the battery disconnect switch to the ON position.

4. Turn the ECS to the LOCAL position.

5. Monitor the voltage on the digital voltmeter.

6. Turn the ECS to the OFF position.

7. Turn the battery disconnect switch to the OFF position.

8. Remove the digital voltmeter and replace all wires.

Expected Result:

The voltage measures 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC.

  Repair: Verify that 24 ± 3 VDC is present on terminal 1 of the mag relay. If voltage is not present on terminal 1 of the mag relay, troubleshoot the wiring to the breaker for the mag relay. If voltage is present on terminal 1 of the mag relay, install a new mag relay. Verify that the problem is no longer present.

  Stop.

• Not OK - The voltage does not measure 24 ± 3 VDC. Proceed to Test Step 5.

Test Step 5. Check the Voltage to the Starting Motor Relay.

1. Connect one probe of a digital voltmeter to the -Battery terminal. Connect the other probe of the digital voltmeter to wire F701-BR on terminal 3 of the starting motor relay.

2. Turn the battery disconnect switch to the ON position.

3. Turn the ECS to the LOCAL position.

4. Monitor the voltage on the digital voltmeter.

5. Turn the ECS to the OFF position.

Expected Result:

The voltage measures 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC.

  Repair: The coil of the starting motor relay or the wire 102-GN/YL may be open. Check wire 102-GN/YL for continuity to the -Battery terminal. Check the coil of the starting motor relay for continuity. Repair wire 102-GN/YL or replace wire 102-GN/YL. Replace the starting motor relay if the coil is bad. Verify that the problem is no longer present.

  Stop.

• Not OK - The voltage does not measure 24 ± 3 VDC. Proceed to Test Step 6.

Test Step 6. Check the Voltage from the ECM to the Connector of the Generator and the Engine.

1. Turn the battery disconnect switch to the OFF position.

2. Disconnect the generator and the engine harness connector J3/P3.

3. Remove the wire P3-24 from the generator and engine connector J3/P3. Remove the wire from the side of the connector that is going to the generator.

4. Reconnect the generator and engine connector J3/P3.

5. Connect one probe of a digital voltmeter to the wire from P3-24. Connect the other probe of the digital voltmeter to the -Battery terminal.

6. Turn the battery disconnect switch to the ON position.

7. Turn the ECS to the LOCAL position.

8. Monitor the voltage on the digital voltmeter.

9. Turn the ECS to the OFF position.

10. Turn the battery disconnect switch to the OFF position.

Expected Result:

The voltage measures 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC.

  Repair: The problem is most likely in the wiring between the generator and engine harness connector J3/P3 and terminal 3 of the starting motor relay. Repair the wire F701-BR.

  Stop.

• Not OK - The voltage does not measure 24 ± 3 VDC. Proceed to Test Step 7.

Test Step 7. Check the "Crank Signal" from the ECM.

1. Turn the ECS to the OFF position.

2. Turn the battery disconnect switch to the OFF position.

3. Disconnect ECM connector J2/P2.

4. Remove wire P2-13 from ECM connector P2.

5. Install a wire jumper into the socket for P2-13.

6. Connect a digital voltmeter between the wire jumper in P2-13 and the -Battery terminal.

7. Turn the battery disconnect switch to the ON position.

8. Turn the ECS to the LOCAL position.

9. Monitor the voltage on the digital voltmeter.

10. Turn the ECS to the OFF position.

11. Turn the battery disconnect switch to the OFF position.

12. Remove the wire jumper. Replace all wires and reconnect the ECM connector.

Expected Result:

The voltage measures 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC.

  Repair: Check the wiring between the ECM connector P2-13 and terminal 24 of the generator and engine connector J3/P3 for continuity. Repair the connectors or wiring and/or replace the connectors or wiring.

  Stop.

• Not OK - The voltage does not measure 24 ± 3 VDC.

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

  Stop.

Test Step 8. Check the Solenoid.

1. Turn the battery disconnect switch to the OFF position.

2. Connect one end of a suitable piece of 10 AWG wire to the +Battery terminal. Connect the other end to the S terminal of the starting solenoid for one second.

Expected Result:

The starting solenoid activates while the wire is connected to the S terminal.

Results:

• OK - The starting solenoid activated. The problem appears to be in the system wiring.

  Repair: Verify that the circuit breaker for the starting motor relay has not tripped. Check and repair the wiring between the S terminal of the starting solenoid and terminal 2 of the starting motor relay. Verify repairs by checking starting solenoid operation.

  Stop.

• Not OK - The starting solenoid did not activate. The problem appears to be in the starting solenoid.

  Repair: Temporarily install a new starting solenoid. Verify that the problem is no longer present.

  Stop.