PUMP AS 1252991 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the system when one of the following diagnostic codes is active or easily repeated:
1779-05 Fuel Rail #1 Pressure Valve Solenoid current below normal
1779-06 Fuel Rail #1 Pressure Valve Solenoid current above normalNote: The fuel rail pump is installed on the engine at the factory. The fuel rail pump is not a serviceable part. The fuel rail pump delivers fuel into the fuel rail at very high pressure.Use this procedure to troubleshoot the system when there is a active diagnostic code or if a diagnostic code can easily be activated or when another procedure has directed you here.The fuel rail pump solenoid is used to control the output from the fuel rail pump. The solenoid receives an electrical supply from the ECM. The fuel rail pump solenoid is then energized when the fuel is required to be pumped into the fuel rail. Varying the timing of the voltage to the solenoid controls the fuel delivery from the fuel rail pump.When the fuel rail pump solenoid is deactivated, the fuel that is not sent to the fuel rail is returned to the fuel tank.The fuel rail pump solenoid forms part of the closed loop control system for the fuel rail pressure in conjunction with the fuel rail pressure sensor, the ECM and the software. The fuel rail pressure sensor measures the fuel pressure in the high pressure fuel rail. The signal from the fuel rail pressure sensor is processed by the ECM and software. The measured pressure is compared to the desired fuel rail pressure for the given engine operating conditions.If the fuel rail pump solenoid fails, it is likely that the fuel will not be pumped into the high pressure fuel rail. The engine will shut down or the engine will fail to start. The fuel rail pressure can be observed on the status screen of the electronic service tool.
Illustration 1 g01459101
Schematic of the circuit for the fuel rail pump solenoid
Illustration 2 g01459102
Pin locations for the electrical power supply circuit on the P2 connector
(25) Fuel rail pump solenoid PWM signal
(26) Fuel rail pump solenoid return Test Step 1. Inspect the Electrical Connectors and the Harness
Electrical shock hazard. The fuel rail pump solenoid uses 63 to 73 volts.
Turn the keyswitch to the OFF position.
Thoroughly inspect the harness connector P2/J2 and the suspect connector P532. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the solenoid connector P532 and the connector pins 25 and 26 that are associated with the fuel rail pump solenoid. Refer to illustration 2.
Check the harness for abrasions and for pinch points from the battery to the ECM. Check the harness for abrasions and for pinch points from the key switch to the ECM.
Use the electronic service tool in order to perform a "Wiggle Test". The "Wiggle Test"is used to identify intermittent connections. Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted. The harness is free of