3512B Petroleum Engines with the ADEM 2 Electronic Control Module Caterpillar

The Electronic Control Module (ECM) has the ability to crank the engine when the circuits for the Start/Run/Stop Switches are complete. 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. If crank terminate speed is not reached before 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.

Illustration 1	g00824270

Test Step 1. Check for Connector Damage.

1. Turn the engine control to the OFF position.

2. 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.

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:

The connectors and wiring should be free of the following problems: damage, corrosion, abrasion and incorrect attachment.

Results:

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

• Not OK - The connectors and/or wiring are not okay.

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

  STOP

Test Step 2. Attempt To Start the Engine

1. Turn the engine control to the ON position.

2. Turn the Start/Run/Stop Switch to the STOP position.

3. Start the Cat ET.

4. Observe the start-up mode parameter on the Cat ET status screen.

5. Close the circuit for the Start/Run/Stop Switch. Monitor the start-up mode parameter.

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.

Expected Result:

The status screen for the start-up mode parameter should display "CRANK".

Results:

• OK - The start-up mode parameter on the status screen on the Cat ET displays "CRANK". The engine starts.

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

  STOP

• Not OK - The engine will not crank. Proceed to test step 3.

Test Step 3. Manually Crank The Engine.

1. Turn the Start/Run/Stop Switch to the STOP position.

2. Connect a voltmeter between terminal 3 on the mag relay and engine ground.

3. Turn the Start/Run/Stop Switch to the START position.

4. Open the Electronic Instrument Panel. Momentarily activate the manual crank switch.

Expected Result:

The voltage should measure 24 ± 3 VDC. The mag relay should activate and the starting solenoid should activate.

Results:

• OK - The relay activates and the engine starts. Proceed to test step 4.

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

  Repair: Check the operation of the manual crank switch. Inspect the wiring and/or connectors for damage between the Battery and the mag relay. Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

• Relay(s) Active - The relay activates but the starting motor did not activate. Proceed to test step 5.

• Relay(s) Not Active - The relay did not activate. Proceed to test step 7.

Test Step 4. Test the ECM.

1. Turn the engine control to the OFF position.

2. Disconnect P2 from the ECM. Remove the wire F701-BR from P2-13. Install a wire jumper into the socket for P2-13.

3. Connect a voltage test lamp between the wire jumper in P2-13 and engine ground.

4. Turn the engine control to the ON position.

5. Activate the override for the starting motor relay.

6. Turn OFF the override for the starting motor relay.

7. Turn the engine control to the OFF position. Remove the wire jumper. Reconnect ECM connector J2/P2.

Expected Result:

The voltage test lamp should illuminate.

Results:

• OK - The voltage test lamp illuminated. The problem is not with the ECM. The problem is most likely in the wiring between P2 and the mag relay.

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

  STOP

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

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

  STOP

Test Step 5. Check the Solenoid.

1. Turn the engine control to the OFF position.

2. Connect a voltmeter between wire 150-OR on the Start solenoid and engine ground.

3. Turn the engine control to the ON position.

4. Activate the override for the starting motor relay.

5. Turn OFF the override for the starting motor relay.

6. Turn the engine control to the OFF position. Remove the extra wires.

Expected Result:

The voltage should be 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC. The problem appears to be in the starting solenoid.

  Repair: Install a new starting solenoid. Ensure that the problem is no longer present.

  STOP

• Not OK - The voltage does not measure 24 ± 3 VDC. The problem appears to be in the system wiring. Proceed to test step 6.

Test Step 6. Check the Voltage from the Mag Relay.

1. Connect a voltmeter between terminal 2 on the mag relay and engine ground.

2. Activate the override for the starting motor relay.

3. Monitor the voltage on the voltmeter.

4. Turn OFF the override for the starting motor relay.

Expected Result:

The voltage should measure 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC.

  Repair: There is a problem in the wiring and/or connectors between the mag relay and the start solenoid. Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

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

Test Step 7. Test the Mag Relay.

1. Disconnect the Start/Run/Stop Switch.

2. Measure the voltage between terminal 1 on the mag relay and engine ground.

Expected Result:

The voltage should measure 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC.

  Repair: Check continuity of wire 229-BK from the mag relay to the − Battery terminal. If the wire is okay replace the mag relay.

  STOP

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

  Repair: The problem appears to be in the wiring between the + Battery terminal and the mag relay. Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP