Troubleshooting P0628 fuel pump low voltage
 

Have 2006 Ram 3500 showing P0628 fuel pump low voltage code. Replaced 6+ yrs batteries with new, cleaned terminals. Installed local 0-30 psi glycerin gauge on the bottom of the fuel filter. Pressure runs 10 psi at idle and same at 2000 rpm static under no load. Flow test through filter drain valve yields 1000 ml fuel in 25 secs when switch is in on position. Engine Code still will not clear. Original owner, has original OEM intank fuel pump.

There is large wiring connection midway down the chasis and another connection to the fuel tank. This are difficult to get to in order to disconnect and have not been checked.

Need recommendations.