89 1/2 ton sub 4x4 5.7 check engine light wont come on

Check the socket. It may be damaged, corroded...

socket is good. if put in other area works fine

If there is power to the socket, then the ground needs to be missing. Otherwise the light would have to come on.

Ok, there is two wires from the instrument harness cluster going to the socket. Pink/white & brown/white. Pink/white seems to be hot all the time. So that makes brown/white the ground? But if I ground that wont the light stay on and not switch off after motor starts? And thank you very much for the help!

That would make sense. There is a chance the hot wire is on because the light should be on. It does go off when you turn the key off, correct?

Well the light dont come on at all except if I ground out the brown/white wire with my test light.I have not tried turning the key off when it is grounded though. The brown/white wire goes to the ECM according to my schematics, but if im understanding right its just a ground and wont cause a problem with the ECM. Another question, I have low fuel pressure, would a relay cause that or is the problem at the pump?

You would have to check voltage to the pump.