3500B and 3500C Locomotive Engines Caterpillar

Use this procedure in order to troubleshoot the emergency stop system or use this procedure if the diagnostic code in Table 1 is active or easily repeated.

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 switch is turned to the ON position, the engine will begin the sequence for start-up. When the emergency stop switch is activated the ECM will stop firing the injectors. The engine will stop. When an emergency stop signal is received by the ECM, the ECM will activate the output for the solenoid valve that controls the air shutoff valve. When the solenoid valve activates, the air shutoff valve closes removing the intake air to the engine.

The switch at the air shutoff valve allows the ECM to determine if the air shutoff valve is open or closed. If the shutoff valve is closed, the switch is in the closed position and the ECM will not start the engine. The air shutoff valve must be manually opened in order to start the engine.

The electrical power to the input for the keyswitch must be turned OFF for 15 seconds in order to reset the engine ECM after an emergency stop condition.

Illustration 1	g01314139
Typical schematic

Illustration 2	g01258500
P1 ECM connector (P1-5) Digital return (P1-23) Emergency shutdown C (P1-28) Emergency shutdown D

Illustration 3	g01258540
Connector "A" (Terminal 21) Emergency shutdown D (Terminal 23) Emergency shutdown C (Terminal 25) Digital return

Illustration 4	g01258549
Connector "G" (Terminal 3) Emergency shutdown D (Terminal 7) Emergency shutdown C (Terminal 37) Digital return

Illustration 5	g01234146
Location of ECM connectors

Test Step 1. INSPECT ELECTRICAL CONNECTORS AND WIRING

1. Turn the breaker for the ECM to the OFF position.

2. Thoroughly inspect the ECM connectors J1/P1. Inspect all of the other connectors in the circuit. Refer to Troubleshooting, "Inspecting Electrical Connectors" for the proper procedure for inspecting system wiring.

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. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.

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. The harness and wiring are free of corrosion, of abrasion, and of pinch points.

Results:

• OK - The harness and wiring are OK. Proceed to Test Step 2.

• Not OK - There is a problem in the connectors and/or wiring.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.

  Verify that the repair eliminates the problem.

  STOP

Test Step 2. CHECK THE STATUS WHILE THE EMERGENCY STOP SWITCH IS ACTIVE

1. Connect Caterpillar Electronic Technician (ET) to the service tool connector.

2. Turn the breaker for the ECM to the ON position.

3. Start Cat ET.

4. Observe the status of the emergency stop switch on Cat ET.

5. Activate the emergency stop switch. If multiple emergency stop switches have been installed, ensure that any other emergency stop switch has not been activated.

Expected Result:

The status for the emergency stop switch reads "ON".

Results:

• OK - The status for the emergency stop switch reads "ON". Proceed to Test Step 3.

• Not OK - The status 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 solenoid valves retract and that the air shutoff valves are open.

2. Observe the status of the emergency stop switch on Cat ET.

Expected Result:

The status for the emergency stop switch reads "OFF".

Results:

• OK - The status 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, refer to Troubleshooting, "Inspecting Electrical Connectors".

  STOP

• Not OK - The status for the emergency stop switch does not display "OFF". Proceed to Test Step 4.

Test Step 4. INSTALL A JUMPER WIRE AT THE EMERGENCY STOP INPUTS TO THE ECM

1. Turn the breaker for the ECM to the OFF position.

2. Disconnect ECM connector J1/P1.

3. Remove wire F715-PU(Purple) from the ECM connector P1-23. Install a wire jumper into the socket for P1-23.

4. Remove wire F719-BR(Brown) from the ECM connector P1-28. Install a wire jumper into the socket for P1-28.

5. Connect ECM connector J1/P1.

6. Turn the breaker for the ECM to the ON position.

7. Observe the status of the emergency stop switch on Cat ET.

8. Fabricate a jumper wire.

   Connect the wire jumpers in socket P1-23 and P1-28 to the digital return at socket P1-5.

9. Observe the status of the emergency stop switch on Cat ET.

10. Turn the breaker for the ECM to the OFF position. Restore the wiring and the connectors to the original configuration.

Expected Result:

The status of the emergency stop switch reads "ON" when the jumper is not installed. The status of the emergency stop switch reads "OFF" when the jumper is installed.

Results:

• OK - The status 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 status for the emergency stop switch is not displaying the proper states.

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

  STOP

Test Step 5. CHECK THE SWITCHES AND THE WIRING WHEN THE EMERGENCY STOP IS ACTIVATED

1. Disconnect the ECM connector J1/P1.

2. Activate the emergency stop switch. If multiple emergency stop switches have been installed, ensure that all other emergency stop switches are not active.

3. Measure continuity between P1-5 and P1-23.

4. Measure continuity between P1-5 and P1-28.

5. Deactivate the emergency stop switch.

6. If multiple emergency stop switches are installed, close the emergency stop switch and perform this test step on all of the emergency stop switches that are installed in the circuit.

Expected Result:

When the emergency stop switch is activated, the resistance measurements indicate an open circuit.

Results:

• OK - The resistance measurements indicate an open circuit. Proceed to Test Step 6.

• Not OK - The resistance measurements do not indicate an open circuit. There is a short circuit in the emergency stop switch or an emergency stop switch is activated.

  Repair: 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. Deactivate the emergency stop switch. If multiple emergency stop switches have been installed, ensure that all other emergency stop switches are not active.

2. Measure continuity between P1-5 and P1-23.

3. Measure continuity between P1-5 and P1-28.

4. Reconnect all connectors.

Expected Result:

When the emergency stop switch is not activated, the resistance measurements indicate a short circuit.

Results:

• OK - The resistance measurements indicate a short circuit.

  Repair: The emergency stop switch is functioning correctly. There may be an intermittent problem. If the problem is intermittent refer to Troubleshooting, "Inspecting Electrical Connectors".

  STOP

• Not OK - The resistance measurements do not indicate a short circuit. There is an open circuit in the emergency stop switch and/or the wiring.

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

  STOP