3512B Oil Well Servicing Engine (ADEM III) 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 2.

If two different signals are detected during the powerup, the ECM will determine that one of the signals is incorrect. If this condition is detected, the ECM will allow the engine to be started and the engine will be allowed to run. A diagnostic code will be activated and the code will also be logged. If both of the signals become open the engine will stop.

The customer can install multiple emergency stop switches. When the start/run/stop switch is turned to the RUN 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 from 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 three seconds in order to reset the engine ECM after an emergency stop condition.

Illustration 1	g01228349
Location of the J1/P1 and the customer connector (typical left side engine view) (1) J1/P1 ECM connectors (2) Customer connector

Illustration 2	g01227331
Typical schematic for the emergency stop switch

Illustration 3	g01227424
Terminal locations at the P1 ECM connector (P1-5) Digital return (P1-21) Start/Run/Stop input 1 (P1-22) Start/Run/Stop input 2 (P1-23) Emergency stop signal "C" (P1-28) Emergency stop signal "D" (P1-52) +Battery (P1-53) +Battery (P1-55) +Battery (ECM) (P1-56) Air shutoff (NO) (P1-63) −Battery (P1-65) −Battery (P1-70) Keyswitch

Illustration 4	g01227669
Terminal locations at the customer connector (Terminal 01) +Battery (Terminal 02) +Battery (Terminal 04) Air shutoff (Terminal 09) Digital return (Terminal 16) Emergency stop signal "D" (Terminal 17) Emergency stop signal "C" (Terminal 23) Start/Run/Stop input 1 (Terminal 24) Start/Run/Stop input 2 (Terminal 27) Keyswitch (Terminal 34) −Battery (Terminal 35) −Battery

Test Step 1. Check for Active Diagnostic Codes

1. Remove electrical power from the ECM.

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

3. Restore electrical power to the ECM.

4. Check for an active 337-2 diagnostic code.

5. Remove electrical power from the ECM.

Expected Result:

The 337-2 diagnostic code is not active.

Results:

• OK - The 337-2 diagnostic code is not active. Proceed to Test Step 2.

• Not OK - The 337-2 diagnostic code is active.

  Repair: If the diagnostic code 337-2 is active, the wires between the ECM and the emergency stop switch are in opposite states. Check the wires for an open circuit.

  1. Disconnect the J1/P1 ECM connector.

  2. Measure the resistance between P1-23 at ECM connector P1 and terminal 2 at the emergency stop switch.

  3. Measure the resistance between P1-28 at ECM connector P1 and terminal 2 at the emergency stop switch.
  If the resistance measurement indicates an open circuit, repair the wires and/or connectors in the harness between the emergency stop switch and the ECM.

  STOP

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

1. Restore electrical power to the ECM.

2. Start Cat ET.

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

4. 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 have been opened.

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. Test the Operation of the Emergency Stop Switch

1. Disconnect the wire that is on terminal 1 of the emergency stop switch.

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

3. Short circuit the wires from terminal 1 and from terminal 2 at the emergency stop switch.

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

5. Remove electrical power from the ECM. Restore the wiring and the connectors to the original configuration.

Expected Result:

The status for the emergency stop switch reads "ON" when the wire is disconnected from terminal 1 and the wires are not shorted. The status for the emergency stop switch reads "OFF" when the wires are shorted at the switch.

Results:

• OK - The status for the emergency stop switch is displaying the proper states. The problem is not with the ECM or the wiring to the ECM.

  Repair: Replace the emergency stop switch. Verify that the problem is resolved.

  STOP

• Not OK - The status for the emergency stop switch is not displaying the proper states. The problem is in the wiring between the emergency stop switch and the ECM. Proceed to Test Step 5.

Test Step 5. Install a Jumper Wire at the Inputs to the ECM from the Emergency Stop Switch

1. Remove electrical power from the ECM.

2. Disconnect ECM connector J1/P1.

3. Remove the wire from terminal location P1-23 at the ECM connector. Install a jumper wire with a socket on one end into P1-23. Do not allow the end of the jumper wire to contact any other wire in the harness or engine ground.

4. Remove the wire from terminal location P1-28 at the ECM connector. Install a jumper wire with a socket on one end into P1-28. Do not allow the end of the jumper wire to contact any other wire in the harness or engine ground.

5. Remove the wire from terminal location P1-5 at the ECM connector. Install a jumper wire with a socket on one end into P1-5. Reconnect wire from this terminal location to the other end of the jumper wire.

6. Restore electrical power to the ECM.

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

8. Fabricate a jumper wire.

   Connect the jumper wires at terminal locations P1-23 and P1-28 to the jumper wire that is in the digital return at terminal location P1-5.

9. Observe the status for the emergency stop on Cat ET.

10. Remove electrical power from the ECM. Restore the wiring and the connectors to the original configuration.

Expected Result:

The status for the emergency stop switch reads "ON" when the jumper wires are not shorted to the digital return. The status for the emergency stop switch reads "OFF" when the jumper wires are shorted to the digital return.

Results:

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

  Repair: If the ECM shows that the emergency stop is active and the emergency stop switch has not been activated, the likely cause is an open circuit in the digital return wire. Check the wire for continuity between the emergency stop switch and the ECM. Make the necessary repairs to the harness.

  STOP

• 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