BOLT 3054905 - Caterpillar

System Operation Description:Use this procedure in order to troubleshoot the emergency stop system or use this procedure if the diagnostic code in Table 2 is active or easily repeated.
Table 1
Diagnostic Codes Table    
Description     Conditions which Generate this Code     System Response    
337-2 Remote Emergency Stop Switch erratic, intermittent, or incorrect     The two inputs from the emergency stop switch are in the opposite state.     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. 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 connectorsTest Step 1. Inspect Electrical Connectors and Wiring
Turn the breaker for the ECM to the OFF position.
Thoroughly inspect the ECM connectors J1/P1. Inspect all of the other connectors in the circuit. Refer to Troubleshooting,