PLUG 2416157 - Caterpillar

System Operation Description:Use this procedure to troubleshoot suspect problems with the circuit for the indicator lamps.This procedure covers the following diagnostic codes:
323-3 Engine Shutdown Lamp : Voltage Above Normal
324-3 Warning Lamp (Action) : Voltage Above Normal
443-3 Crank Terminate Relay : Voltage Above Normal
445-3 Run Relay : Voltage Above NormalThe master Electronic Control Module (ECM) has four outputs in order to indicate the status of engine operation: "Run Relay", "Crank Terminate Relay", "Engine Control Alarm Status" and "Fault Relay". These outputs can be used to energize indicator lamps or the outputs can be used to interface with other controls.The ECM opens an internal circuit in order to set an output to OFF. The ECM closes the circuit in order to set the output to ON. When the circuit is closed and the output is ON, the ECM allows a maximum current of 0.3 amperes to flow through the circuit to a ground that is inside the ECM.If excessive current flows through the circuit, a diagnostic code is generated. A short circuit to the +Battery side will also activate a diagnostic code. Note: These circuits do not sink enough current for illumination of standard incandescent lights. If a lamp is burned out, replace the lamp with the lamp that is specified in the engine's Parts Manual."Run Relay" - This output indicates that the engine is in the "Run" status. The engine will start soon or the engine is running. While this output is energized, a short circuit to a positive voltage source or excessive current through the circuit will cause a diagnostic code to become activated. The master ECM cannot diagnose this output while the output is OFF."Crank Terminate Relay" - This output indicates that the engine rpm is greater than the programmed engine speed that is required for disengagement of the starting motor. While this output is energized, a short circuit to a positive voltage source or excessive current through the circuit will cause a diagnostic code to become activated. The master ECM cannot diagnose this output while the output is OFF."Engine Control Alarm Status" - This is the alarm output. This output indicates that the master ECM has detected an electrical problem or an abnormal operating condition. While this output is energized, a short circuit to a positive voltage source or excessive current through the circuit will cause a diagnostic code to become activated. The master ECM cannot diagnose this output while the output is OFF."Fault Relay" - This is the shutdown output. This output indicates that a potentially damaging operating condition was detected by the master ECM. The master ECM has shut down the engine. While this output is energized, a short circuit to a positive voltage source or excessive current through the circuit will cause a diagnostic code to become activated. The master ECM cannot diagnose this output while the output is OFF.Note: Some indicators may obtain the status of the engine via a data link. If all of the indicators are not directly controlled by