I've got a 97 f150 that came stock with a six cylinder. When that took a dump, I swapped in a 99 5.4 V8. Due to the fact that I didn't research this swap, I ended up with a wiring nightmare. Very little matched wiring-wise between the two powerplants (ie- wire to pin in the computer harness). Did get everything ironed out with the exception of the tach. I guess I'm missing something somewhere. Anyone with any knowledge on this subject please throw it my way. Thanks!

 

Does it work at all or does it just read wrong?
If it reads wrong then you will have to ground one of the wires that go to the tach.

 

doesn't work at all. The wiring schematics I have say that the tach is pin #48 (white/pink wire in the ECU plug) . I'm getting the feeling that this might be wrong. Everything else is fine though.