charmedbridge

We recently replaced the tranny in our 97 F-150 4.6 ltr 4x4. Upon completion my husband went to start the truck and nothing! Fuse 24 was blown under the hood. That fuse controls the pcm. He went and bought another and right away it blew again. He then unplugged the tranny and tried again, nothing. I asked him what he unplugged altogether before this great adventure took place. It was the tranny of course, the o2 sensors (exhaust was cut and removed and later welded back) and the starter. We have had the starter inspected and it was good, brand new infact! I guess my question is, if i unplug the o2 sensors do you think it will fire? Starters fine and tranny too! He is at autozone right now having the diode checked and the relay for the pcm!!! I want a simple fix!!!! P.S. The diode doesnt register and autozone doesnt have one! Its a lil fuse that has a side peg and a regular fuse peg position. Also the fuel pump doesnt kick in when key is turned! But upon reading our Haynes book, the pcm controls that function.

ymeski56

Both sensors have signal, signal return & heater wires. Check length of wires for short conditions. The truck would run (in failsafe mode) if disconnected, I believe.

charmedbridge

Thanks for your answer. We think it might be the case where the pcm goes with the tranny! I think we need the pcm that came outta the truck we got the loaner tranny from. We are calling around today and I hope we get some answers!! Thanks again.

ymeski56

Ya, tranny has to match PCM. and in most cases, the engine.