hello all,

im new to the form and looking for some advise with this newly acquired bronco


bought the truck about a month ago and just now getting around to working on it, as of right now its a crank no start and i believe it to be a bad pcm and after looking into it the engine was swapped from a 5.0 to 5.8 and now im not sure how to or where to order a rebuilt or new to me pcm.

should i order the pcm from the trucks vin number or for the engine? the pcm in the bronco now i believe matches the engine as the numbers off it indicate its a 95 5.8 and my bronco is a 94 with originally a 5.0.

also just some info when i purchased the bronco it was a crank no start but it was cold out pushed the truck into a warm shop and it ran(kinda)
after towing the truck home it never ran again. looked at the pcm and had all the signs of being bad.

so whats my next move?
really appreciate any info that can be given excited to drive it and its pretty clean for a 94 bronco.

 

What is fuel pressure at the engine?
What codes are present?
Does the fuel pump run constantly with the key in the run position?
Is the truck MAF or SD?
Is the 5.8 all original?
Does it look like it came from a 1/2 ton truck? Do you know what the differences are?

 

Other missing info:
Exactly which PCM is in it now?
To ID the original PCM, what is the cal code on the sticker on the door pillar?
And since 94 PCMs have a lot of TCU in them, which transmission is in it now? (Not that a mis-match here would prevent running (at least in Park))
Does the current transmission match the TRAN code on the VIN sticker on the door pillar?
What specifically are the PCM's "signs of being bad" that you see?
When did it last run properly?

Mechanical - it ran for you recently, so there's probably nothing here to stop it from running some more. It's always worth doing at least a compression test on a newly acquired engine.
PCM - Ideally should match both the engine and trans, and output only the 'all clear' code
Fuel - Clean, good pressure at the rail, flashing noid light
Spark - At the plug. Lots of ways to test this. Also, the 'midnight ignition check' to make sure there are no sparks where there shouldn't be

Since this has apparently had some major surgery, then been in the hands of someone that failed to get/keep it running, I'd give it a careful and detailed inspection to make sure that absolutely everything is there and that nothing has been Frankensteined onto it.

If the PCM actually is bad, pretty much every parts store can get them. Amazon sometimes fails to charge a core charge, and even when they do can still be the cheapest around. I've also gotten one without a core charge from Summit. I personally would never buy one from ebay - too many of the PCM sellers there are just junkyard vampires and couldn't test, let alone rebuild, one to save their life.
Please keep in mind that external problems can cause a PCM to fail or to stop a good one from working, so chambering one into the parts shotgun can be a pointless waste of time and money - especially if the new one just gets damaged by said external problem.


I'm definitely ignorant of this and would appreciate knowing for junkyard trips. I've seen that Bronco cal codes are just a small subset of F150 cal codes. What are the differences?

 

i have zero fuel pressure and fuel pump doesnt prime when key rolled forward.
no codes present due to no communication with pcm
bronco is SD
motor looks all stock i believe it was owned by an older guy who just went crazy ordering accessories from a jc whitney book
i believe it came from a bronco with a 5.8 due to the pcm matching a 95 bronco 5.8 and my bronco is a 94 and vin code says it should be a 5.0

 

pcm in it now is F5TF-12A650-BXA
i will have to double check transmission

i took the pcm out and opened it up and it smelled really bad and all capacitors were smoked and a few diodes were also burned up had a tech place near me replace it all but still no run.
other info is i have no fuel pump prime and zero spark unless i unplug the pcm i get spark back truck ran once since i owned it but didnt run great barley made it on the trailer for the tow home.

 

They used to tell us in school to give the processors the "smell" test
You are on to something
I found a new one for mine on Ebay
there should be remans out there
Try to find the correct one using the trucks calibration number
I now have my old processor for a spare that I can replace the caps on

 

That is a bad sign... sounds like it is FUBAR so time to get another one.

Another indication the PCM is toast. But knowing that the engine has been swapped I have to wonder if the PO kept the original 5.0 engine wiring harness or if he used the one that came with the donor motor. If he did use the one that came with the 5.8 there is a possibility for circuits to be incomplete or miswired where the engine harness connects to the chassic harness. What I suggest you do is open up that big block connector and compare the pin locations on each side to see if they match up and that there isn't a bunch more wires on the engine side than the chassis side. If there is then the engine harness is for a MAF setup and that won't work with a truck built around SD.. the engine harness has to be changed.