I already did that to confirm my thought process before posting the last time, I tested my 94 5.8L.

Everything intact and the VMV is functioning as it should be. I tested it same conditions I suggested you test yours, continuity tests "open" on the computers side of the valve.

Myself I wouldn't buy a new or reman computer, I buy a used one from a bone yard.

Keep in mind my truck is OBDI / EEC-IV, it would help if someone here with the system yours has would do the same test for us a minute. Make sure that circuit shows "open" key off, key on and then key on engine idling.

Just so as you don't buy a computer only to find its the same issue yet.

 

When you say Was I that unlucky to get two POS rebuild pcms? where they attempts to fix this very problem? or is this a new problem, that was something else?

 

Yes it was for this problem. I have had this problem for well over a year I just took a break away from trying to find it. I smogged it last Jan. by filling both tanks, clearing the P0443 code and going straight to the smog station before the vmv got a command. It passed no problems but later on it came back. I have a friend that lives in San Diego, CA that has looked the junkyards for a pcm match with no luck. Where I live there is not much selection. If you happen to have a contact I would much appreciate it. My computer is a F6TF-12A650-AAC with a calibration code 6-64S-R06. I think the latest number is F6TF-12A650-AAE but I'm not sure.

 

Ok knowing that I gotta say the odds you had a bad computer causing it, replaced it with two computers with exactly the same issue gotta be slim to none.

Sounds more likely something else is causing the problem. Right back around to what rla2005 was saying early on, somethings effecting the computer in such a way its causing it to ground that pin all the time even and even with the key off.

Someone else with a "working model" just like yours, same year "OBDII" would work, test it for us for comparison value would be helpful but even at that I gotta believe the computer shouldn't be grounding that pin with the key off or even with the key on.
Maybe just maybe for a few minutes after first started, during "fast idle" warm up to clear vapor in the tank built up while parked yea ok maybe, but not when the key is off.
Chance I might be wrong but if it supplies vac to the vapor canister/system all the time, 100% duty cycle, why involve the computer in it to start with?

 

I will say that both rebuilt pcms acted totally different from each other and different from mine. My truck runs fine with my pcm but one of theirs barely idled and the other one missed at high speeds. I did run them for about 20 miles in case they needed to learn my truck but no change. I also found out the company had a terrible reputation. I also realized later that they never even asked me for a calibration code, wouldn't that matter?

 

funny thing this was me 3 years ago. i had changed out the vmv and the tct(solinoid pack) and the problem persited. i had my shop i worked at at the time run a seperate wire to the vmv to verfiy that wasnt the concrn, well the wiring was not .it was the pcm. you will not find a used pcm for a 1996 , they just are not out there. i have a napa reman computer in mine as that was the only available ones to get. i did pop the cover on mine before i sent in the core and you could see there was a spot inside where you could tell there was an issue. justin

 

Thanks Justin. Did Napa ask for a calibration number and mileage to match yours? And did you have to go to Ford and get it programed?

 

I had to bring mine to the bone yard, they stated 7 possible for it. They didn't ask for the CC they wanted to see the label on the computer itself to get me the right one. Was no question as to its had been original to truck. I didn't bother with what it said for mileage, didn't care and ultimately wouldn't matter. I have the info saved here on my computer, mile on truck when changed and mileage listed on replacement.

Did they ask to see the one you have first?

And no if it didn't run right with either one of them it wasn't a good test, could have been bad computers or simply the wrong one. So that didn't actually show you anything, it still might be the computer then.

 

Hope this helps a little.

I would check the transmission range sensor area as well.







Thats about it for my input. I suspect a ground circuit issue

 

mike the codes you listed in your post # 18 is all you need to give them, and no, this truck the pcm is a plug n play

 

1996 FORD F150 ENGINE COMPUTER F6TF-12A650-AAC 5.8L AT | eBay

 

Thanks for all the help and diagrams. I had some more time to check everything again with the transmission unplugged, same results. I found the Napa pcm part number and will probably try that when I have the cash. I hope that works or I will be selling a rebuilt Napa pcm, and maybe a 1996 f150 to someone that does not have to deal with California. Merry Christmas!

 

Hello,

Not the update you guys might want to hear because I still have not ordered the rebuilt pcm from Napa. I have been looking for local donor trucks with no luck. Just a thought, somebody said they noticed burnt components on their pcm before they sent it away for a core. Does any know where i can get a schematic of the pcm itself? I have access to soldering equipment and microscope to fix this kind of problem. I have alot of soldering experiance with small components like surface mount capacitors and diodes. I am confident I can remove and replace the component, the trick will be finding the bad component(s).

Thanks

 

Hunt here and maybe you can find what your looking for
Ford Bronco And F-150 Links - FORD BRONCO

 

Hello,

I finally got the courage to order another rebuilt computer this time through Napa. By the way, my truck is running fine the original computer. I put the new computer in (third computer) and got a totally different problem than the other rebuilt ecm's. This time the truck stumbles and blows black smoke and my obd2 reader cannot even talk to the truck. I thought maybe it needs to learn the truck so I tried to take it for a drive after letting it smoke for a few minutes. I was surprised it idled in reverse and when I put it in drive it barely moved like it was stuck in third or maybe in od. Not sure if a "flash" from my local ford dealer would fix this? I will contact Napa this week and see what they can do. Just saw a used ecm on ebay that might work but I need to get my $ back from Napa. I will keep updating as this frustration continues.