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

The Electronic Control Module (ECM) receives two signals from the Emergency Stop Switch. The signals allow the ECM to determine the status of the Emergency Stop Switch. The ECM will shut down the engine when both of the signals are open. When both of the signals are connected to the digital return the Emergency Stop Switch is NOT active and the engine will run. Refer to Illustration 1.

If two different signals are detected during the powerup, the ECM will determine that one of the signals is incorrect. A diagnostic code will be logged and a diagnostic code will remain active. The engine will continue to run when the ECM detects two different signals. If both of the signals are open, the engine will stop.

The customer can install multiple Emergency Stop Switches. When the Start/Run/Stop Switches are active, the engine will begin the sequence for start-up. When an Emergency Stop Switch is active the fuel supply is cut off and the engine will not run. When an emergency stop signal is received by the ECM, the ECM will trigger the hydraulic solenoid valves that control the air shutoff valves. When the hydraulic solenoid valves activate, the air shutoff valves close removing the intake air to the engine.

The right hand switch for the right air shutoff and the left hand switch for the left air shutoff are part of the emergency stop circuit. The right hand switch for the right air shutoff and the left hand switch for the left air shutoff are in the closed position when the air shutoff valves are open. The right hand switch for the right air shutoff and the left hand switch for the left air shutoff ensures that the ECM knows the position of the air shutoff valves. The air shutoff valves must be manually opened in order to start the engine.

The main power to the ECM must be turned OFF for three seconds in order to reset the engine ECM after an Emergency Stop condition.

Illustration 1	g00861631
Typical example

Test Step 1. Check for Connector Damage.

1. Disconnect main power.

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

  STOP

Test Step 2. Check the Status while the Emergency Stop Switch is Active.

1. Activate the Emergency Stop Switch. If multiple Emergency Stop Switches have been installed, ensure that any other Emergency Stop Switch has not been activated.

2. Start the Caterpillar Electronic Technician (ET).

3. Connect the main power.

4. Observe the status of the Emergency Stop Switch on the Cat ET.

Expected Result:

The parameter for the Emergency Stop Switch should read "ON".

Results:

• OK - The parameter for the Emergency Stop Switch reads "ON". Proceed to test step 3.

• Not OK - The parameter for the Emergency Stop Switch does not read "ON". Proceed to test step 4.

Test Step 3. Check the Status while the Emergency Stop Switch is Not Active.

1. Deactivate the Emergency Stop Switch.

   Note: Ensure that the hydraulic solenoid valves retract and that the air shutoff valves are open.

2. Observe the status of the Emergency Stop Switch on the Cat ET.

Expected Result:

The parameter for the Emergency Stop Switch should read "OFF".

Results:

• OK - The parameter for the Emergency Stop Switch reads "OFF".

  Repair: The Emergency Stop Switch is functioning correctly. There may be an intermittent problem. If the problem is intermittent, perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".

  STOP

• Not OK - The parameter for the Emergency Stop Switch does not display "OFF". Proceed to test step 4.

Test Step 4. Install a Jumper Wire at the Input to the ECM from the Emergency Stop Switch.

1. Disconnect the main power.

2. Disconnect ECM connector J1/P1.

3. Remove wire F715-PU from the ECM connector P1-02. Install a wire jumper into the socket for P1-02.

4. Remove wire F719-BR from the ECM connector P1-20. Install a wire jumper into the socket for P1-20.

5. Connect the main power.

6. Observe the status of the Emergency Stop Switch on the Cat ET.

7. Disconnect the main power.

8. Fabricate a jumper wire.

   Connect the wire jumpers in socket P1-02 and P1-20 to the digital return at socket P1-29.

9. Connect the main power.

10. Observe the parameters for the emergency stop on the Cat ET.

11. Disconnect the main power. Restore the wiring and the connectors to the original configuration.

Expected Result:

The parameter for the Emergency Stop Switch should read "ON" when the jumper is not installed. The parameter for the Emergency Stop Switch should read "OFF" when the jumper is installed.

Results:

• OK - The parameter for the Emergency Stop Switch is displaying the proper states. The problem is not with the ECM. Proceed to test step 5.

• Not OK - The parameter for the Emergency Stop Switch is not displaying the proper states.

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

  STOP

Test Step 5. Check the Switches and the Wiring when the Emergency Stop Switch is Activated.

1. Disconnect the main power.

2. Disconnect the ECM connector J1/P1.

3. Activate the Emergency Stop Switch. If multiple Emergency Stop Switches have been installed, ensure that all other Emergency Stop Switches are not active.

   Note: Ensure that the hydraulic solenoid valves retract and that the air shutoff valves are open.

4. Measure the resistance between ECM pins P1-29 and P1-20.

5. Measure the resistance between ECM pins P1-29 and P1-2.

6. Deactivate the Emergency Stop Switch.

7. Continue this process for all the Emergency Stop Switches if multiple Emergency Stop Switches are installed.

8. Reconnect all connectors.

Expected Result:

When the Emergency Stop Switch is activated, the resistance should be greater than 20,000 Ohms for all of the Emergency Stop Switches.

Results:

• OK - The resistance is greater than 20,000 Ohms. Proceed to test step 6.

• Not OK - The resistance is less than 20,000 Ohms. There is a short circuit in the Emergency Stop Switch or an Emergency Stop switch is activated.

  Repair: Check the Emergency Stop Switch for proper operation. Replace the Emergency Stop Switch, if necessary. Repair the connectors and/or wiring or replace the connectors and/or wiring.

  STOP

Test Step 6. Check the Switches and the Wiring when the Emergency Stop is NOT Activated.

1. Disconnect the main power.

2. Disconnect the ECM connector J1/P1.

3. Deactivate the Emergency Stop Switches. If multiple Emergency Stop Switches have been installed, ensure that all other Emergency Stop Switches are not active.

4. Measure the resistance between P1-29 and P1-20.

5. Measure the resistance between P1-29 and P1-2. Record this resistance.

6. Reconnect all connectors.

Expected Result:

The resistance should read less than 10 Ohms.

Results:

• OK - The resistance is less than 10 Ohms.

  Repair: The Emergency Stop Switch is functioning correctly. There may be an intermittent problem. If the problem is intermittent, refer to the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".

  STOP

• Not OK - The resistance is greater than 10 Ohms. There is an open circuit in the Emergency Stop Switch and/or the wiring. Proceed to test step 7.

Test Step 7. Check the Resistance between the Switches for the Air Shutoff.

1. Disconnect the main power.

2. Disconnect the ECM connector J1/P1.

   Note: Ensure that the hydraulic solenoid valves retract and that the air shutoff valves are open.

3. Deactivate the Emergency Stop Switches. If multiple Emergency Stop Switches have been installed, ensure that all other Emergency Stop Switches are not active.

4. Disconnect the connector for the switch of the right air shutoff. Measure the resistance between the pins for the connector for the right air shutoff.

5. Disconnect the connector for the switch of the left air shutoff. Measure the resistance between the pins for the connector for the left air shutoff.

6. Disconnect the wire(s) from one side of the Emergency Stop Switch. Measure the resistance between the terminals on the Emergency Stop Switch.

Expected Result:

The resistance should read less than 10 Ohms.

Results:

• OK - The resistance is less than 10 Ohms for all of the resistance measurements.

  Repair: The wiring and/or the connectors between the components is faulty. Do a resistance check on each wire between the components. Disconnect one end of the wire from the circuit. Measure the resistance from one end of the wire to the other end of the wire. If the resistance measures more than 10 Ohms the wire and/or connectors need to be repaired.

  STOP

• Not OK - The resistance is greater than 10 Ohms.

  Repair: If the resistance measures more than 10 Ohms the component needs to be repaired. Replace the suspect component and recheck the circuit.

  STOP