99 740il will not crank

whan i turn the key on evrything lights up but whan i turn the key ferther he starter do not click and all the lights on the dach remain to de on. i put on a difrent DMU,EWS weight box under the stering wheel, steering collom with key, ALL FROM ONE CAR. and a new neutral safety switch. the ONLY way it will crank is if i hook up a wier from the starter relay to the black/yellow wier( under the steering whell there is a 8 wier square conacter i believe, it hooks up to the back side of the steering wheel colon lock ) then it will crank but it will only give 4.5v to the ignition coils. can some one give me some tips?