3406E and 3456 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 START/RUN position. The engine control will begin the first crank cycle. 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 start 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/RESET or COOLDOWN/STOP position and then turning the ECS to the START/RUN position.

Note: Applications that are equipped with an Electronic Modular Control Panel II (EMCP II) must set "Total Number of Crank Cycles" parameter to zero (0).

Illustration 1	g01068711
Circuit schematic for the engine start relay

Test Step 1. INSPECT ELECTRICAL CONNECTORS AND WIRING

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

2. Inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the other connectors that are associated with the start relay. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" 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 (53 lb in).

5. 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 are free of corrosion, of abrasion and 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 THE ENGINE CONTROL SWITCH (ECS)

1. Verify proper operation of the ECS.

Expected Result:

The ECS is operating properly.

Results:

• OK - The ECS is operating properly. Proceed to Test Step 3.

• Not OK - A problem was found with the ECS.

  Repair: Repair the ECS. Refer to Troubleshooting, "Engine Control Switch (ECS)" or refer to Troubleshooting, "Engine Control Switch (ECS) (EMCP II)" for additional information. Verify that the repair has eliminated the problem.

  Proceed to Test Step 3 if the problem has not been eliminated.

Test Step 3. START THE ENGINE

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

2. Turn the ECS to the STOP position.

3. Connect the Cat ET to the service tool connector.

4. Observe the status of "Startup Mode" on Cat ET and turn the ECS to the START position.

Expected Result:

The ECS cranks the engine for a time that is equal to the programmed "Cycle Crank Time". The ECS cranks the engine until the engine speed becomes greater than the value that is programmed for "Crank Terminate Speed". Also,"Startup Mode" displays "Crank", while the engine is cranking.

Results:

• OK - The relay activates and the engine starts. Proceed to Test Step 4.

• Not OK - The relay activates but the starting motor did not activate. Proceed to Test Step 6.

Test Step 4. MANUALLY CRANK THE ENGINE

1. Turn the ECS to the START position.

2. Open the electric instrument panel and activate the manual crank switch. Listen for the magnetic relay to activate. click ON.

Expected Result:

The magnetic relay clicks ON and the starting motor solenoid activates.

Results:

• OK - The relay activates and the engine starts. Proceed to Test Step 5.

• Not OK - The relay activates but the starting motor did not activate. Proceed to Test Step 6.

• Not OK - The relay did not activate. Proceed to Test Step 7.

Test Step 5. TEST THE ECM OUTPUT

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

2. Disconnect connector P2 from the ECM. Use a jumper wire to short P2:07 (PWM return) to P2:19 (Starter relay).

3. Reconnect connector P2 to the ECM.

4. Connect one probe of a test lamp to the wire jumper at P2:07 (PWM return). Connect the other probe of the voltmeter to the jumper wire at P2:19 (Starter relay).

5. Turn the ECS to the STOP position. Use Cat ET in order to activate the "Starting Motor Relay" override.

   Note: This procedure will cause 444-05 starting motor relay open circuit to become logged. Delete the diagnostic code after completion of this test procedure.

6. Use Cat ET, in order to turn the override for the "Starting Motor Relay" to the OFF position.

7. Turn the ECS to the OFF/RESET position and remove the jumper wires.

Expected Result:

The voltage test lamp illuminates.

Results:

• OK - The test lamp illuminates. The problem is not with the ECM. The problem is most likely in the wiring between connector P2 and the mag relay. Recheck this part of the system and make all necessary repairs. Verify that the repair has eliminated the problem.

  STOP

• Not OK - The voltage test lamp did not illuminate.

  Repair: Refer to Troubleshooting, "Replacing the ECM".

  STOP

Test Step 6. CHECK THE STARTING MOTOR AND THE SOLENOID

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

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

Expected Result:

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

Results:

• OK - The starting motor activated. The problem appears to be in the system wiring. Ensure that the circuit breaker for the magnetic relay has not tripped.

  Repair: Check and repair the wiring between the S terminal of the starting motor solenoid and terminal 2 of the mag relay. Verify repairs by checking starting system operation.

  STOP

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

  Repair: Temporarily install a new starting motor solenoid. Verify that the problem is no longer present. Reinstall the old starting motor solenoid. If the problem returns, replace the starting motor solenoid.

  STOP

Test Step 7. CHECK THE MAG RELAY ON THE STARTING MOTOR

1. Turn the ECS to the STOP position.

2. Connect one end of a suitable piece of 18 AWG wire to -Battery terminal. Connect the other end to terminal 4 of the magnetic relay.

3. Connect one end of a second jumper wire to terminal 3 of the magnetic relay. Connect the other end to the +Battery terminal.

4. Test the operation of the magnetic relay by making several intermittent connections and listening for the magnetic relay to actuate. The relay will make a "clicking" sound when the relay is activating.

Expected Result:

The magnetic relay activates when the second jumper wire is connected to terminal 3 of the magnetic relay.

Results:

• OK - The magnetic relay activated.

  Repair: The problem appears to be in the wiring between the magnetic relay and the manual crank switch. Ensure that the circuit breaker for the emergency stop has not been tripped. Make all necessary repairs. Verify that the repairs have eliminated the problem.

  STOP

• Not Ok - The magnetic relay did not activate.

  Repair: The problem appears to be with the magnetic relay. Replace the magnetic relay. If the problem is resolved with the new relay, reinstall the suspect relay and verify that the problem returns. If the problem returns with the suspect relay, replace the magnetic relay.

  STOP