ok guys i just swapped my 06 4.0 into my 98 mazda b3k. well first off the speedometer never goes about 30 and after it gets about 10 mph it starts to bounce. the tranny shifts fine and runs fine. but i can figure it out all the wires for it are hooked up correctly as far as i know (had a ford tech look at the wires) and both of the speedometer wires are hooked up. so what i dont understand is why isnt it reading the mph? could the output shaft speed sensor be bad. would it throw a code if it was bad? does my pcm need a tune? or a reprogram. help

also i dont know if this has anything to do with it but my 4x4 lights are flashing periodically while i drive it. everything seems to be hooked up for that i will double check the wires but it seems to be hooked up to. and from what my friend has told me the speedo and 4x4 on the 06 pcm should be run by the same set of wires.

 

i think if the speed sensor is bad-it throws a abs light
when mine came on and what i thought was the speed sensor-had similar problems, my speedometer would jump up n down, it turned out to be that my rear end was in pieces haha. i dont think thats what is happening to you tho.
and as far as i kno, if the 4x4 lights are flashing-something is happening with the transfer case

 

:/ crap yeah the rear end is still good i just threw a locker in it about 6 months ago. crap this sucks and my 98 didnt have abs so it wouldnt have a light hahaha

 

ive never swapped a motor over before, but i mean start easy stuff-check out the condition of that speed sensor