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

The Electronic Control Module (ECM) has the ability to stop the engine by cutting off the air supply in an emergency situation. The ECM activates the air shutoff solenoid which activates the air inlet shutoff valve.

There are two conditions which cause the engine control to activate the air shutoff solenoid. The first condition occurs when the operator initiates an emergency shutdown. When the shutdown is recognized, fuel is shut off and the air shutoff solenoid is activated. The second condition is for an engine overspeed. Engine overspeed can be a real overspeed condition. Overspeed can be obtained by using the overspeed verify switch.

Regardless of the reason for activation, the main power to the ECM must be turned OFF for three seconds in order to reset the engine control.

Note: The Air Shutoff is optional. A programmable parameter needs to be set with the Caterpillar Electronic Technician (ET) in order to enable the air shutoff.

Note: Ensure that BOTH of the air shutoffs are manually reset after an Emergency Stop in order to start the engine again.

Illustration 1	g00861631
Typical example

Test Step 1. Check for Connector Damage.

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Prevent sparks near the batteries. Sparks could cause vapors to explode. Do not allow jumper cable ends to contact each other or the engine.

1. Disconnect the main power at the Battery disconnect switch.

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 wiring and connectors are okay. Proceed to test step 2.

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

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

  STOP

Test Step 2. Test the Circuit.

1. Start the Cat ET.

2. Connect the main power.

3. Access the override on the Cat ET. Activate the override for the air shutoff.

Expected Result:

The air shutoff solenoid should activate. The Cat ET should indicate "ON".

Results:

• OK - The air shutoff solenoid activates.

  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 air shutoff solenoid does not activate. Proceed to test step 3.

Test Step 3. Check the Voltage at the Air Shutoff Solenoid.

1. Disconnect the main power.

2. Disconnect wire G971-BR from the terminal "C" of the air shutoff solenoid.

3. Connect a voltage test lamp between G971-BR and engine ground.

4. Connect the main power.

5. Access the override on the Cat ET. Activate the override for the air shutoff.

6. Monitor the voltage test lamp.

7. Disable the override for the air shutoff.

   Note: This test will cause a 446-05 CID-FMI to be logged. Be sure to delete this CID-FMI when this test is completed.

8. Reconnect all connectors.

Expected Result:

The voltage test lamp should illuminate.

Results:

• OK - The voltage test lamp illuminated. Proceed to test step 5.

• Not OK - The voltage test lamp did not illuminate. Proceed to test step 4.

Test Step 4. Check the Voltage from the ECM.

1. Disconnect the main power.

2. Remove wire G971-BR from ECM connector P2-19. Install a wire jumper into the socket for P2-19.

3. Connect the main power.

4. Connect a voltage test lamp between wire G971-BR and the engine ground.

5. Access the override on the Cat ET. Activate the override for the air shutoff.

   Note: This test will cause a 446-05 CID-FMI to be logged. Be sure to delete this CID-FMI when this test is completed.

6. Disable the override for the air shutoff.

7. Disconnect the main power.

8. Remove the wire jumper. Reconnect all connectors.

Expected Result:

The voltage test lamp should illuminate when the override is in place.

Results:

• OK - The voltage test lamp illuminated. The problem appears to be in the wiring between the ECM and the air shutoff solenoid(s). Proceed to test step 5.

• 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 Wiring to the Solenoid.

1. Disconnect the main power.

2. Disconnect the solenoid connector.

3. Disconnect ECM connectors J1/P1 and J2/P2.

4. Install a jumper wire between the terminals at the solenoid connector.

5. Measure the resistance between P1-5 and P2-19 at the ECM connectors.

Expected Result:

The resistance should measure less than 10 Ohms.

Results:

• OK - The resistance measures less than 10 Ohms.

  Repair: The solenoid is not operating correctly. Replace the solenoid. Verify that the circuit is operating correctly.

  STOP

• Not OK - The resistance measures more than 10 Ohms.

  Repair: There is an open or excessive resistance in the wiring harness. Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP