Code P0628

[Dick Langendorff]

Looked this code up and it is, "fuel pump relay control circuit low voltage".



How would I check this out and correct? I posted and rec. many replies for help about the truck quitting and not being able to start again. The feeling was a failed LP. I still think that is the problem, however, this is the Code that came up.



04 qc 235hp 460tq. Stock, Stock.



Thanks for some input and help.



Dick Langendorff

-- email address removed --

925-550-8727

 

[JLandry]

Dick,



See the attached couple of pages from the Dodge Powertrain Diagnostic Manual for details on locating the problem.



As a substitute for activating the lift pump with a DRBIII scan tool mentioned in step 1 of the trouble shooting procedures, instead you can turn the ignition key to the run position and bump the starter (but don't start the engine). This will activate the lift pump for 25 seconds and you'll be able to hear it running.



The bottom line is this trouble code can be set by a problem with either the wiring harness, the lift pump, or the ECM. In order of probability, I would guess the lift pump would usually fail most often, then the wiring harness would have a bad connection or short, then last the ECM would have a problem.



Hope this helps,



John L.

 

[MMeier]

Dick, see my post in your other thread.