SPN 970 - FMI 2 (Diagnostic Code: Remote Emergency Stop Switch Erratic, Intermittent, or Incorrect)

CDL Code: 337-2

Figure 1.1 - Remote Emergency Stop Switch (337-2)

Code and Description:

→337-2 Remote Emergency Stop Switch Erratic, Intermittent, or Incorrect.

 

Condition which Generate this Condition:

→The two inputs from the Emergency Stop Switch are in the opposite state.

System Response:

→The code is logged.

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.

Figure 1.2 - Illustration 3512C Engine

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 three seconds in order to reset the Engine ECM after an Emergency Stop condition.

Test Step 1. Check for an Active Diagnostic Code

A. Turn the main disconnect switch to the ON position.

B. Start Caterpillar Electronic Technician (ET). Read More: How to Connecting Caterpillar ET Software to the ECM.

C. Check for an active 337-2 Diagnostic Code (refer to Figure 1.1 above).

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. Turn the main disconnect switch to the OFF position.

2. Disconnect the J1/P1 ECM connector.

3. Measure the resistance between P1-23 at ECM connector P1 and terminal 2 at the Emergency Stop Switch.

4. 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 between the Emergency Stop Switch and the ECM.

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

A. Turn the main disconnect switch to the ON position.

B. Start Cat ET.

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

D. 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.

Figure 1.3 - Remote Emergency Stop Switch (On)

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

A. Deactivate the Emergency Stop Switch. Note: Ensure that the solenoid valves retract and that the Air Shutoff Valves are open.

B. 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.

→Not OK - The status for the Emergency Stop Switch does not display "OFF". Proceed to Test Step 4.

Figure 1.4 - Remote Emergency Stop Switch (Off)

Test Step 4. Test the Operation of the Emergency Stop Switch

A. Disconnect the wire that is on terminal 1 of the Emergency Stop Switch.

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

C. Install a jumper wire between the wire from terminal 1 and terminal 2 at the Emergency Stop Switch.

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

E. 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 jumper wire is not installed. The status for the Emergency Stop Switch reads "OFF" when the jumper wire is installed.

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.

→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 Input to the ECM from the Emergency Stop Switch

A. Turn the main disconnect switch to the OFF position.

B. Disconnect ECM connector J1/P1.

C. Remove wire F715-PU(Purple) from the ECM connector P1-23. Install a wire jumper with a socket on one end into P1-23. Do not allow the end of the wire jumper to contact any other wire in the harness or Engine ground.

D. Remove wire F719-PU(Purple) from the ECM connector P1-28. Install a wire jumper with a socket on one end into P1-28. Do not allow the end of the wire jumper to contact any other wire in the harness or Engine ground.

E. Remove wire 998-BR(Brown) from the ECM connector P1-5. Install a wire jumper with a socket on one end into P1-5. Reconnect wire 998-BR(Brown) to the wire jumper in socket P1-5.

F. Turn the main disconnect switch to the ON position.

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

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

I. Observe the status for the Emergency Stop on Cat ET.

J. Turn the main disconnect switch to the OFF position. Restore the wiring and the connectors to the original configuration.

Expected Result: The status for the Emergency Stop Switch reads "ON" when the jumper wire is not installed. The status for the Emergency Stop Switch reads "OFF" when the jumper wire is installed.

Results:

→OK - The status for the Emergency Stop Switch is displaying the proper states. The problem is not with the ECM.

→Repair: If the Emergency Stop is active and the Emergency Stop Switch is not 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.

→Not OK - The status for the Emergency Stop Switch is not displaying the proper states.

→Repair: Replace the ECM.

Read More:

Caterpillar ET Software: Online Licensing

Accessing the SIS Links on Caterpillar ET Software

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