Error Code P0628 - Fuel Pump Relay Control Circuit Malfunction / P0628 Low Voltage Detected at The Fuel Lift Pump Relay.
Does this mean I will have to replace the entire pump or can you replace the relay only?

 

Entire LP most likely.

 

If you have the external fuel pump on the fuel filter housing I would replace that first. Does the fuel lift pump relay click when you bump the starter? If not replace the lift pump relay

 

Other than in the fuse/relay box where do I find the relay? Can't seem to find it. Thank you.

 

I'm sorry the fuel pump relay is intergrated into that ecm module. You most likely have a bad fuel pump. Check power and ground and lift pump and if ok replace the lift pump. There is a retrofit fuel pump available which converts your external fuel pump to intank type fuel pump. Also includes flash update to ECM and wiring harness to convert to intank type pump.

 

Appreciate all the help. As dumb as it may be, I am not familiar with the location of the ECM, is it on the drivers side firewall? Is it a sealed unit or can it be opened?
Thank you!

 

ECM is a sealed module and it mounted on the left side of the engine block. Lift pump is mounted on fuel filter housing.
1 - ENGINE CONTROL MODULE (ECM)
2 - ECM MOUNTING BOLT
3 - 50-WAY CONNECTOR
4 - SUPPORT PLATE
5 - 60-WAY CONNECTOR

 

Thank you!

 

Just changed the transfer pump but still get codes: P0628 & P0633. Gonna take her out for a test drive now and see what happens. Do you have to perform a reset or is there still trouble? Somewhere I saw a list of codes but can't find them now, anyone have the link to the page with the error codes?
Thank you!