1990 F250 ECM success story--help with part numbers--hopefully

[GM POS]

Just wanted to share my experience with replacing my ECM. Most of this is just a summary of what I've found from many different forum posts on many different sites. It's a long story but it bundles a bunch of stuff I found along the way in to one post instead of picking up little bits from various threads.

So I got in "Big Ugly" (trust me, she is) one day and as I started down the road she acted like she wanted to stall and I got a CEL. Turned around and went straight home (thankfully happened less than a 1/2 mile from home). When I tried to pull the code using the "paperclip" method I wasn't getting any codes flashing. Also when I turned on the key the fuel pump would not stop running. Did my research online and found out this is a sign of a bad ECM, although I never did get the burning smell some spoke of. So like any good, red blooded American I cracked open the ECM and sho'nuff there were two capacitors with burned contacts. So like any good, red blooded American I tried replacing them and just ended up, once again, demonstrating that I suck at soldering (figured what did I have to lose). I was able to get the new capacitors to "stay" but the problem remained the same (and yes I removed the conformal coating where I was trying to solder).

So now the real fun started as when I started to look up part numbers I discovered there are like a dozen different choices. LOTS of searching online never yielded a 99.9% confidence level I wanted (as most places won't take back electrical stuff). Some people said the code in big numbers (mine was S9C) was the most important but when looking up part numbers I never saw this number anywhere.

The numbers on my ECM's label I found to be the ones needed were E9TF-12A650-AK2A. The closest part number I found online was E9TZ-12A650-AKA. Some places even had it listed without the 12A650 part as that is just a group classification (or something like that) so some sites drop it. Now for the "F" and "Z" difference the numbers printed or stamped on some parts are just "engineering numbers" and may differ slightly from the eventual retail part number. I've seen this before so I wasn't too concerned. Now the part I couldn't find any info on was the last bit (AK2A as opposed to the AKA).

I'm sure you've noticed in your own searching that the last part of that part number (AKA, ARA, AJB, etc.) refers to what transmission type and emissions package (Federal, California, High Altitude) are on your vehicle. Mine has the AOD (or AOT) and I live in Ohio. The AKA part was referring to the High Altitude emissions ECM which was a bit confusing because Ohio isn't exactly know for it's vast mountain ranges and high altitude living(truck could have come from Colorado originally or it doesn't really matter). Again my concern was the fact a "2" was on my label and not in the listed part number. I've seen them change a number or letter but not add one.

In the end the "2" did not matter. I ordered the E9TZ-12A650-AKA and when I got the new one the numbers all matched perfectly (when the new/reman one came it had "AK2A" in the part number even though listed as "AKA").

So to summarize you would want to order the one that has the closest first four numbers/letters (E9TZ, E7TZ, FOPZ, FOTZ, etc.) and then the closest last four numbers/letters (AKA, ATA, AJA, etc.). That's what I did and it worked out good. Installed the new ECM and the truck fired right up and ran perfectly.