ECU swap, dealing with PATS

So my 98 Mazda B4000 has PATS because one of the previous owners swapped in a 99 4.0L SOHC from an explorer. I confirmed it does have the PCM from the SOHC and not the OHV.

Anyways when I go to start the truck with KOEO the fuel pump runs continuously, and doesn't shut off after the set amount of time. I never let it run like that for very long. I already swapped the fuel pump and tank pressure sensor a few months back because of a P0232 code (Fuel pump secondary voltage high). We have traced all wires, replaced the inertia switch and fuses/relay. The only thing left to try according to the Ford Service Manual is the PCM. I have read that a continuously running fuel pump in a Ford is usually the PCM. On a side note the truck runs and starts just fine, but I am tired of the CEL always being on.

So the issue I have is if I swap the PCM with another my keys/PATS module won't be compatible with the new PCM. I can get a used PCM for a 98-99 Explorer or Mountaineer 4.0L SOHC for pretty cheap, but the issue is getting the dealer to reprogram it. I already called one of the local Ford/Mazda dealers in RI and they said they wouldn't even do it because my truck "contains parts from different vehicles." I asked another local dealer and they told me they don't have/use the NGS system anymore and directed me to the nearby Mazda dealership! I don't even want to ask another dealer because I don't like getting the run around and their condescending responses.

I have read that some locksmiths can reprogram keys for these vehicles, but can they reprogram my existing keys to a new PCM? Is it roughly the same process? I currently have 2 keys for the ignition, and 1 for the doors (likely the original), so I shouldn't need a new cylinder. So what are my options for getting a new PCM to work with my truck? I have considered going to the junkyard and seeing if I can just get the PCM, ignition, at least 1 key, and the PATS module from another truck. But that is a crap shoot, especially finding the key. I am located in RI, if anyone knows a nearby dealer/locksmith that would be willing to help me out that would be great. Any help would be appreciated!

The dealership that said they don't have an NGS anymore, call them up, tell them to pull their heads out of their asses and use the IDS to do it because NGS won't even program keys as far as I know, but the IDS will work on your vehicle.

Then call up the first dealership, ask to talk to the owner or the general manager and ask why his service department can't manage to do something as simple as a key program just because the vehicle is modified a little bit, if they are good enough to be called dealership techs. If he is even half as concerned about customer perception as my GM is you will have an apology, a free oil change, and maybe a free tank of gas.

If you were closer I'd do it for you myself.



A locksmith will probably not be able to do what you need. Most of them don't actually program keys, they clone the chip on an existing one so the computer thinks it is seeing a key that has already been programmed.

Thanks man, I had a feeling that I was going about it wrong. I may have given them more info than necessary about the engine swap and the fuel pump code. I supposedly talked to someone who call himself the service manager of one dealership. The truck runs so I don't have to have it towed. I was just hesitant to buy the new PCM if I wouldn't be able to get it swapped.

There is one more local dealer I haven't tried, although I had a dispute with their parts dept almost a year ago over them selling me the wrong EGR tube for my old truck. The way they handled it left a sour taste in my mouth, so I try to avoid them. I am going to get the PCM now that I know it can be done. In your opinion do you think it is the PCM? Or am I missing something that could cause that issue of the pump running continuously and reading high voltage when it is commanded off? Thanks again man, super helpful as usual!

The relay could be getting stuck. If you can get it out and swap it with another one of the same design you can test that. IIRC your horn relay should be the same, and that will be an easy test too, swap them, hit the horn, and if it stays on you, and the rest of the neighborhood, will know that is the problem. The only other test I can think of is to see if the pump keeps running without it's relay installed at all, that would indicate a short.

Barring all that I would suspect the PCM.



Another thing you could try for getting it fixed, call the service department, tell them that you need the PCM replaced, and all you want from them is swap, program, parameter reset and key reprogramming, and no questions. You will get the best results from the PCM swap if a proper PMI (Programmable Module Installation) is done, and they are best started with the original module still in the vehicle.

Cool man, now I know exactly what I need from the dealer, I appreciate it. I have been focusing my attention on other issues because the truck still starts and runs well. But this is something that I want to iron out, especially due to the CEL light it's throwing.

Would there be any difference between a 98 or 99 PCM with the same part number? The truck and trans are a 98, but the engine is a 99. It has a returnless system I believe cause I only see one fuel line. I only ask because I read that some 98s had the return system. I have found several PCMs for both years, and they are cheap ($25-$60) likely because they have to be programmed. I will try the relay swap and removal test before I shop for a replacement PCM.