VALVE AS-FLUID SAMPLING 7X3387 - Caterpillar

Probable Causes
An external shutdown or a customer shutdown was requested.
The power supply becomes disconnected from the engine control system.
The master Electronic Control Module (ECM) has lost the supply voltage for the speed/timing sensor.
There is a problem with the fuel supply.
A cylinder or cylinders are misfiring.Recommended Repairs
External Shutdown or Customer Shutdown
Check the master ECM and the Integrated Temperature Sensing Module (ITSM) for logged codes of events that are shutdowns.Power Supply to the Engine Control System
Refer to Troubleshooting, "Electrical Power Supply".
Inspect the ground strap and the power supply for connections that are loose and/or corroded.
Inspect the electronic control modules and the terminal boxes for proper installation of the connectors.Speed/Timing Sensor
A loss of supply voltage to the speed/timing sensor will cause a shutdown. Refer to Troubleshooting, "Engine Speed/Timing Sensor".Fuel Supply
Check the fuel supply pressure.
Inspect the fuel lines for foreign objects and for obstructions that can block the fuel supply.Misfiring Cylinders
For a shutdown that is due to misfiring cylinders, the shutdown is likely to occur only when the engine is operating under a load.The Caterpillar Electronic Technician (ET) and the ITSM can be used to detect a misfiring cylinder. Use the following procedure:
Use the "Data Link/Select ECM" screen on Cat ET to select the ITSM.
Select "Diagnostics/Diagnostic Tests".
Select the suspect cylinder and click the "Start" button in the lower left corner of the screen.Cat ET will display a graph of the cylinder's exhaust gas temperature. The transformer's secondary circuit, the engine speed, and the desired engine speed are also displayed.Locate the misfiring cylinder. Check the following components for failure: spark plug, extender, ignition transformer and primary wiring. Inspect the extender for signs of pin holes and/or of arcing.Refer to Troubleshooting, "Ignition Transformers Secondary Circuit and Spark Plugs".