I have a 94 F250 that just died when I hit a small speed bump. I found the inertia switch & its not poped so I check if I had any power to the inertia switch with light,, No power !! So I figure the relay is bad . I was told its in the Fuse box on left side of compart under hood . I change them all & still no power. Ive been told the relay is next to the master cylinder on the fire wall .. I cant seem to locate it . But if all the relays do work & still no power to inertia switch what could it be?? Please help It has the 4.9l 6 cyl Thank you all for your help

 

Look in cab for fuse center on passenger side...I think that is where my husband and father in law found it. It is a non serviceable part on my 04 Expedition so we had to bypass it and once we did that, it started right up.