ENG 1 Fuse Headach

1996 4X4 Blows eng1 fuse when key is turned on but will still start & run in limp mode. Had two fault codes which were P0340 & P0102. I cannot see any underhood problems with wire harness but could the harness to the pump be bad ? Would it still start & run down the road with pump harness problems ?
Seems like maybe an VCM problem but thats why I'm starting this post because I'm scratching my head. Rough idle symptoms but it will drive down the road with the service light on. Should I unplug the VCM & turn the key on to see if it still pops the fuse ? HELP ?!?!

If you blow the fuse that fast then you probably have a short to ground either on a wire or a component on that circut.

I was working on a truck that had the exact same problem and some one had replaced the tranny and when the bolted the cross member back in the truck they pinched the power wire for the fuel pump between the frame and the cross member, after a while the movement of the cross member rubed through the covering on the wire and it started to short.

Thanks for the reply & it's ironic that you said something related to the trans. I just found a short in the harness running down pass the tranny due to previous repairs done by a shop when the shift cable broke & got wrapped around the front driveshaft. Thanks for the reply & thanks to this great forum.
Have a great day !!

Glad that I could help.