I discovered something usefull while hooking up my alternator regulator. The "shut down" wire that feeds into the PCM has the same on and off characteristics of the fuel pump feed. This wire comes from the relays under the hood and goes to the PCM. It is dark green with an orange stripe on the 1999. It is fused with a 30 amp fuse and is an important function on the gas engined trucks but does little on this one. I used it for my regulator feed. If you lost the fuel pump feed on the PCM, this one will give the same function. Also it is an igniton on wire from either side of the engine with strong fuseing.

 

I thought the pump supply wire supplies lower voltage for lower pressure at start up.
Does the regulator wire do the same?

 

NO it does not lower the voltage, but the on off cycles are the same.