My truck:
1990 F150 Custom / 4.9 liter I6 300 / 4 speed with OD manual transmission / 4x4 / long bed.

The issue:
I bought this truck about 3 months ago and just learned the the ECU that is in the truck was replaced by the wrong one (FOAF-14A459-AA). As a result, I need to replace the ECU, but since I don't have the original and Ford made 7-10 different ECU's for 1990, I don't know which one I need. I've been told that it's very important to have the right unit and after doing two weeks of research, I still don't have a straight answer. I've talked with Ford Dealerships, local mechanics, etc, but no one seems to really know what the correct ECU is. Most people refer me to two ECU's that correspond to the spec's of my truck, which are (FOTF-12A650-BB) and (FOTF-12A650-CB).

Does anyone have any insight or know of anyone that might? Also, does the ECU need to be flashed / programmed?

Thanks!
Nabor J

 

Post the info on the calibration code from the label in the driver side door jamb, hopefully maybe subford or one of the others visit here regular with all that good info available to them, can use it to answer your question.

Googling it might also provide answer you seek however myself I'd rather wait hear from subford or one of the others to be sure its correct info being used. Opposed to something someone claims be correct found in a google search result!

 

No it's not, as long as the truck runs normally and doesn't throw codes you have a compatable ECU and getting the exact right box won't make any noticable difference.

 

The calibration code is: 0-51 H-R02.

 

The number on the unit is:
F0TF 12A650-BB

Ford Part number is:
F0TZ 12A650-BB

 

Hey Subford,

Your reply is well-received and confirms a lot of what I have heard! I was pretty sure that F0TF 12A650-BB is the original part number. I see that NAPA has part number F0TZ 12A650-BB, so I will likely order it.

Once I get F0TZ 12A650-BB in my hands, do I need to have it flashed via the calibration code that is on the door jamb or is it plug and play?

I'm curious how you came up with these part numbers, do you have a reference guide? This has been quite the chase and thanks for your feedback!

Nabor J1

 

No, there is no flashing. The part number listed gets you the PCM with the correct internal programming for your engine/transmission/truck model.

To find the PCM part number I use Motorcraft's site: www.motorcraftservice.com. Then select Quick Guides/VECI Labels. From there use the pull downs to select your Year/Vehicle/Engine and Calibration Code.

Bill may have something different, but I use the above method.

 

As Conanski pointed out as long as the motor runs right and you don't have a check engine light staring you in the kisser for equipment your model doesn't have? there is no reason to change swap out the computer to a different one.

What issue/s do you have caused by the computer it has now?

Do you get a "system pass" when run the self tests, both KOEO and KOER?

And then if for some reason you have yet to mention do create need to change the computer why buy "new" from napa, at five times the cost. 40-50 bucks tops at most any bone yard get ya a good used one that work just as good as any reman would maybe better. Unmolested OEM.

 

I discovered that the ECU is the wrong one, which was installed by the previous owner and we were getting codes for a 1991 vehicle.

 

Thanks for the info!

 

Great link

 

Ford started the transition from 2 to 3 digit codes in 1991. I still fail to see a big issue here. Please, before spending money, give us more details of the issue(s) and codes you may be getting. They may not be caused by the newer PCM.

 

In short, I am positive that the current ECU (FOAF-14A459-AA) in the truck is the wrong one since the original owner told me he wasn't sure if the shop he used put the right one in.

Here's is the full story of how I came to know that the ECU is bad:

The truck: 1990 F150 Custom / I6 4.9L 300 / 4x4 / 5-speed standard trans.

I bought the truck 3 months ago and ever since the truck will run great for one week or like crap the next. The truck sometimes runs rough as in missing / jerking a lot and the check engine light came on so I had a mechanic try to read the code. He said he couldn't pull any codes and recommended that I replace the ECU, (this is before I pulled the ECU and noticed that it is the wrong one for the truck! The plugs & wires, fuel filter, and distributor are all new. Although the check engine light comes on sometimes, when I turn the key off and restart it, the light goes off and it runs good for awhile, but then the problem comes back! Everyone who tried to read codes got a variety of them, but the last reading is what was so odd.....I was told the codes were for a vehicle in 1991 and that they were thought to be those for a car, not a truck! The mechanic at the last shop claimed that running the truck with an ECU that isn't the right one and/or one that is failing will cause the intermittent issue I have (see below.) He told me not to drive the truck until he could spend significant time doing more research since this issue is causing the cylinders to heat up, the O2 sensor is now bad, and he is reading only about 15% oxygen out of the tail pipe. He said the proper way to check on these issues is he needs to run tests by using a remote wiring harness and there are several tests that need to be done such as injector tests, etc. He said if it is the ECU causing the issue, that it's not as simple as plug and play if the (wrong) ECU caused other damage to sensors, etc. I'm not familiar enough with this to understand if what I'm being told is accurate or not.....can anyone verify this? I was given a solid reference to this mechanic and he told me it could cost anywhere from $500-$800 to fix. Hmmm.

I think the first thing I need to do is the the correct ECU in the truck and go from there. My main fear is what if running the truck with the wrong ECU caused damage to other parts!

Thanks to you all for helping on this. Although I understand basic mechanics, I'm stumped when it comes to electronic issues!

Nabor J1

 

+1^^^

Are you saying your getting three digit codes rather then two? Your 90 and a 91 should both be throwing two digit. Sounds like rla2005 knows of some 91's that do use the three digit. Same thing regardless, codes are for all the same conditions/issues regardless.

While I can't compare 90 to 91 both are the same "group" I have compared the computer pin outs early verses late model and don't recall ever finding a difference in them. Not a thing that make a notable difference in engine/sensors function anyway.

It'd be helpful if you take a moment and post the codes you do get stating what they are,

KOEO
CM
KOER

And we can go from there, you might have a bad computer rather then it'd being the wrong one. All to often problems are blamed on the computer as a easy out when all else fails. It might be bad however there are often specific symptoms associated with one that is bad.

First thing to do when in doubt is remove it and open the cover, look for damage. Look it over for signs of burn parts and or leaking capacitors signs it had been wet etc. If it doesn't have that air to it of had been "burnt" and looks good otherwise it probably is.

Then there is always the old stand by if you really feel its a problem, just want a different one anyway, pick up a good used one for your model/year put it in and test it see how it runs.

 

I've noticed both three and two digit codes, maybe due to the mechanics having different test gear. Two of the codes were #556-Fuel pump relay primary circuit failure and #527-KAM Failure.

I'm not trusting any codes though until I have the right computer in the truck!