greenthunder7.3
New member
from what i can find this fault is logged when the pcm losses power or a tune is flashed into it. my truck is an early 99 and i suspected i had a bad idm( had injector voltage fault after running buzz test and all wiring was good) so i removed the idm and put on another one i had laying around and it through the p0603. so i cleared it and drove the truck around and when i got back the fault was back. so i cleared it and drove around again and it was back again. so i put another different idm on and it does not throw that fault sooooo i'm assuming i have 2 bad idms? everywhere i have looked it says this fault doesn't have anything to do with the idm. anyone know anything different? thanks