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Does the vehicle run?
the truck runs perfectly
Yes I am
how do i check the VREF voltage?
if the voltage is out of our range what is the solution?
Most likely cause is the fuel pump driver module. Check the circuits of the Fuel Pump Driver Module (FPDM) to verify the cause of the problem. The White (W) wire at FPDM pin 5 should show battery voltage, whenever the ignition key is on, from the fuel pump relay and inertia switch. The Black/Yellow (BK/Y) wire at FPDM pin 3 is a dedicated ground for the FPDM. The Pink/Black (PK/BK) wire at FPDM pin 4 is power out of the FPDM feeding the fuel pump. This circuit should show battery voltage whenever the key is in the run position. The Brown/White (BR/WH) wire at FPDM pin 2 is the fuel pump ground circuit. This circuit is duty cycled with a ground signal from the FPDM based on the command from the Powertrain Control Module (PCM). Back probing this circuit with a jumper wire and grounding it should result in 70+ PSI of fuel pressure if there is power to the fuel pump and the pump is good. The White /Yellow (W/Y) wire at FPDM pin 6 is the command signal sent from the PCM to the FPDM. The voltage on this circuit is generally a 1-5 volt reading, the higher the voltage reading, the higher pressure is being commanded. The Light Blue/Orange (LB/O) wire at FPDM pin 1 is a feedback signal sent from the FPDM back to the PCM
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