lift pump?
 

i put a bd low fp indicator on my truck and when its not running the light is on, i have the fuse tapper ran into my horn fuse. lift pump bad or wrong place to wire it into?

You need to go to your fuse box. There are vacant fues holes that you can use. Find one that is only energized when the ignition key is ON.

the box under the hood or the one inside the door jar?

The one on the inside (drivers side) with the door opened.

oh ok any suggestion to which fuse then

Fuel Pressure
 

If you will read all past posts on Fuel Pressure /Supply or LP/ vp44, you will learn everything about your Dodge/Cummins system.
Good Luck

yeah i read into them last night, i ran it into the windshield wiper fuse. also found out when i hit about 2200 rpms its comes on so i had a friend come over with his fuel psi tester and it was weak. time for a airdog