I recently bought a 1993 Ranger 4.0 and I have various engine codes. I have concluded that I have an aftermarket computer that seems to be throwing out engine codes, likely because the computer doesn't match my vehicle.

The part number listed on the computer is F37F-12A650-BC. I am not 100% on this but from what I've found online, this computer is made specifically for the 2.3L Ranger of the same year. This is based on basic search results and what I've seen on RockAuto - computers for the 4.0 match completely with the exception of the BC at the end while there is exact matches for the part number under the 2.3L engines. I have two EGR codes (327 and 558) but I'm not sure if the 2.3L from that year came standard with an EGR or if it is programmed for California emissions. I am also getting a code 519 (Power Steering Pressure switch/circuit open) and I've search everywhere for the power steering pressure switch or even a lose wire harness where one would go and I can't find anything along the hardware of the Power Steering Pump and its connections/hoses.

Can someone confirm whether or not I'm correct. My primary questions based on what I've said so far are..
Should I replace the computer?
Does the '93 4.0L V6 have a PSP switch?

 

All 1993 Rangers will have these numbers on the computers label F37F-12A650

F3 = 1993, F4-1994, F2-1992
7 = Ranger model, can also be a T for truck
F = department at Ford that designs and troubleshoots the "part"

12A650 = part number for ANY engine computer Ford makes, still used in 2023 for engine computers

The suffix, BC, is the actual "number" you want to match for the specific year and model, Ford never released info on these numbers, no cross references

So Ford engine computers are often listed, in this example, as F37F-BC, the 12A650 is left out since its of no value in IDing a specific computer

There is also a "stamped" on number on the label, larger digits, thats the software that was loaded at the time of vehicle assembly

Go here: https://www.car-part.com/
enter in your info
Part you want is "Computer Box engine"
Search

New window will open and it will list all the engine computers for 1993 Rangers in the F37F-BC format at the end
AT = automatic
MT = manual
This will tell you if the computer firmware(BC) is correct for your Ranger model

 

Yep, the website confirms further that the BC computer is made for the 2.3L.

I guess I'll buy a new one as soon as RockAuto has one in stock, and I have the money to do so. Luckily the website is very straight forward and already has everything sorted by man/auto, drivetrain, and type of emissions. I can also use the website to compare OEM Interchange Numbers so thanks a lot for that. Couldn't find anything like that for the life of me.

What type of issues do you think this could be causing besides the false CEL codes?

 

A 1993 4.0l won't have an EGR system, unless it was sold in Calif in 1993/4
And only the 4cyl Rangers had power steering pump switch, to bump up idle when parking so engine wouldn't stall