ECU/PCM Ford Question

[blkvyyper]

Hello Forum,
I have a quick simple question for the experts and it may sound stupid but here it goes...

Are the PCM's for Fords of a similar yr interchangeable? example: Can i take a PCM from let's say a 1991 ford aerostar xlt and use it in a 1992 ford ranger xlt?

thanks in advance...

BV

 

[RonD]

yes and no, lol.

A PCM has software for the engine size and transmission if it is for an automatic trans.
So you can't put a PCM from a 2.3l Ford vehicle into a Ranger with 3.0l or 4.0l engine and expect it to work.
In 1991 some vehicle used Speed Density software(MAP sensor) while other were using the new MAF sensor software, these are not compatible/interchangeable.

A PCM from a vehicle with an automatic trans will "look for" the automatic trans solenoids on start up, if they are not found then it will turn on the CEL(check engine light), it will still work(assuming engine size is the same) but you may have wandering idle RPMs.

Manual trans PCM won't be able to engage solenoids if installed in a vehicle with automatic, so trans will be slow to shift and generally sluggish.

Good read here on older Ford PCMs: http://oldfuelinjection.packrad.net/page17.html
This page shows PCM codes, and what to look for on yours, there are other pages at this site with more PCM(EEC) info