3508B Industrial Engine with an ADEM 2 Electronic Control Module Caterpillar

The customer's emergency stop switch sends two signals to the Electronic Control Module (ECM). The signals are used to determine if the emergency stop switch is active. The emergency stop switch is active when the switch is in the open state and the two signals are held high. The emergency stop switch is inactive when the switch is in the closed state and the two signals are held low.

If the ECM is powering up and one of the signals from the emergency stop switch is in a different state from the other signal, the ECM knows that one of the signals is faulty. If one of the signals from the emergency stop switch is in a different state from the other signal, the ECM will generate a diagnostic code that remains active until power to the ECM is cycled. The ECM will not allow the crank cycle to begin if the signals are opposite of each other. The ECM will allow the engine to be started manually in this state.

The ECM monitors the emergency stop signals at all times. If the engine is running and one of the signals from the emergency stop switch changes states, the engine will continue to run. The ECM initiates an emergency stop shutdown only when both signals are in the open state during engine operation.

For safety, the ECM will not allow the starting sequence to begin when the emergency stop switch is activated. The engine will not be able to restart.

Illustration 1	g00728931
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 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:

All connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring should be free of corrosion, abrasion or 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 and/or wiring or replace the connectors and/or wiring.

  Stop.

Test Step 2. Check the ON Status of the Emergency Stop Switch.

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

2. Connect the ET.

3. Turn the ECS to the STOP position.

4. Activate the emergency stop switch.

5. Observe the status of the emergency stop switch on the ET.

Expected Result:

The parameter for the emergency stop switch should read "ON".

Results:

• OK - The emergency stop switch is working correctly. Proceed to test step 3.

• Not OK - The parameter for the emergency stop switch does not display "ON". Proceed to test step 4.

Test Step 3. Check the OFF Status of the Emergency Stop Switch.

1. Deactivate the emergency stop switch.

Expected Result:

The parameter for the emergency stop switch should read "OFF".

Results:

• OK - The emergency stop switch is functioning correctly. Stop.

• Not OK - The parameter for the emergency stop switch does not display "OFF". Proceed to test step 4.

Test Step 4. Test the ECM.

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

2. Disconnect connector P1 from the ECM. Remove wires P1-29, P1-02 and P1-24 from ECM connector P1.

3. Locate a suitable jumper wire.

4. Insert the jumper wire at P1. Connect P1-02 and P1-24 to P1-29.

5. Reconnect connector P1 to ECM connector J1.

6. Turn the ECS to the STOP position.

7. Observe the parameters for the emergency stop on the ET.

8. Turn the ECS to the OFF/RESET position. Remove the jumper wire and reinstall all wires.

Expected Result:

The parameter for the emergency stop switch should display "OFF" when the jumper is installed. The parameter for the emergency stop switch should display "ON" when the jumper is removed.

Results:

• OK - The problem is not with the ECM. Proceed to test step 5.

• Not OK - The parameter on the ECM is incorrect.

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

  Stop.

Test Step 5. Check the Switches and the Wiring.

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

2. Disconnect connector P1 from ECM connector J1.

3. Activate the emergency stop switch.

4. Measure the resistance between P1-29 and P1-02.

5. Measure the resistance between P1-29 and P1-24.

Expected Result:

The resistance should be greater than 20,000 Ohms.

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.

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

  Stop.

Test Step 6. Deactivate the Switch.

1. Deactivate the emergency shutdown switch.

2. Measure the resistance between P1-29 and P1-02.

3. Measure the resistance between P1-29 and P1-24.

Expected Result:

The resistance should read less than 10 Ohms.

Results:

• OK - The resistance is less than 10 Ohms. The emergency shutdown switch is okay. Stop.

• Not OK - The resistance is greater than 10 Ohms. There is an open circuit in the emergency shutdown switch.

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

  Stop.