I am having an issue that may require that I replace the ECM. This is on a 2004 F150 5.4L 4X4. The ECM number is 4L3A 12A650 AEE.

I am new to this, but gather that the replacement has to exactly match this for everything to work?

Seems like the first 4 digits denote the year and model. Do the last three digits denote the powertrain options? I've found lots of almost matches on used parts sites. But nothing that exactly matching the last 3 digits yet.

Some folks have said that you can call the dealer and find what will cross with the vehicle using the VIN. My dealer said that they couldn't. Any other source available to find out what can interchange?

Will a ECM swap mess up the PATS key programming?

Thanks

 

You're right about the first four digits.

The last digits (suffix) are the revision level of the PCM. It rolls with hardware changes as well as calibration changes. The dealer can indeed help with getting the correct PCM.

I would strongly discourage you from doing the PCM swap yourself unless you have the NGS (or whatever diagnostic/programming tool Ford is using now). The VID block needs to be populated with tire size, axle ratio, driveline, trans type and engine (to name just a few items). The PATS programming may give you trouble...depending if you have two PATS keys.

This is something that if not done right will cause you to pull your hair out. The physical swap is easy...it is all the programming that needs to be done that will cause you difficulty if you don't have the tool.

 

Silly question - Why do you think you may have to replace the PCM?

In about 12 years now, I can count the number of legitimately failed PCMs I've seen on one hand.