Odd issue with my 1994

[Shran]

I would point to power or ground to the computer, cycling connectors is a good start

Being a '94 it shouldn't have a neutral switch if memory serves. I know my trans from a '89 has one, later '89 ('90 model year) did not, both 2.3L manual trans pre MAF (mid '90 model year change) trucks... I don't remember on the '91 Explorer but I don't think it had one and haven't had any other M5OD's out...

M5OD neutral switches vary, I redid a '93 Explorer earlier this year that did not have one. The '94 Mazda B4000 in my shop right now definitely does. My '92 Explorer does, a '92 Explorer donor truck I junked recently did too. Seems to be another one of those Ranger vs Explorer things.

 

[RonD]

Maybe just throw fuel pump at it?

No, I won't do that, the "just throw" part of it
First symptom was a stall so fuel pump was my go to diagnoses, but then other odd symptoms showed up which can't be down to fuel pump

Got busy and haven't pulled out computer yet, but did drive for 30min, ran fine, dang it
Did get a CEL but went way after a few seconds and never came back, no Codes, just 1 1 1

 

[1990RangerinSK]

At this point, I'm thinking maybe call your local priest? Or an exorcist?

 

[scotts90ranger]

Sounding more and more like a ground issue...

At work we have had several engine harnesses with broken ground wires, annoyingly they were broken at the crimp in the ring terminal, and the wires have glue type heat shrink... That is few and far between, more common is just dirty grounds...

 

[Eddo Rogue]

No, I won't do that, the "just throw" part of it
First symptom was a stall so fuel pump was my go to diagnoses, but then other odd symptoms showed up which can't be down to fuel pump

Got busy and haven't pulled out computer yet, but did drive for 30min, ran fine, dang it
Did get a CEL but went way after a few seconds and never came back, no Codes, just 1 1 1

Meh I was just tryina scare you out of hiccups, or maybe provide dumb luck lol...for the following post may be right...just a dumb bad ground? whats the verdict on a ground check? Scott made sense there....

 

[scotts90ranger]

Checking them is hard, a test light sometimes works but sometimes isn't enough amps, and inconsistent issues are even more annoying... checking resistance is more iffy than a test light, some people swear by a sealed beam headlight across the circuit like a test light on steroids... sometimes if you know where the ground wire is, just tugging on it will either jar it loose or tell you it's not the problem, otherwise the surface just needs to be cleaned...

 

[RonD]

OK, so went to start it today and fuel pump came on full time, and cycling the key off and on didn't reset it this time
And when cranking CEL stayed ON
Didn't try reading codes or rebooting

I pulled the computer and one of the blue caps has leaked and one of its wires is separated

I will replace all 3 blue caps, and there is a diode that looks sketchy

And yes I will test the Grounds on the computer's connector

I bent the cap over to show which one broke, it wasn't like that, lol
Also there is over spray all over my nice clean PCM board, must have been painting the factory when it was built

The diode in question is upper left

 

[wildbill23c]

Hmm, guess its time for a new computer. Maybe a Core i7 with 128GB RAM would work? JK. Makes me want to pull the PCM out of my Ranger and give it a look over. Thing is 30+ years old, wouldn't be a bit surprised to find similar issues with mine.

 

[Alan_nc]

So is there software available to allow you to go into the computer and make changes?

 

[RonD]

The EEC-IV, 60 pin PCMs can't be "re-programmed" but you can add an eeprom to the Service port that will load changes each time you start PCM

The later model, EEC-V, 104 pin, 1995 and up, are easier to re-program

 

[scotts90ranger]

Capacitors do have an unknown lifespan... that would definitely do it.

We had a Windows XP computer at work that crapped out a few months ago, turns out a few capacitors on the motherboard went out, you can't just buy motherboards anymore so we scrounged and found a spare motherboard and stole some capacitors... Some software is proprietary and expensive to replace... just today got a replacement computer and the $800 software that made that computer special...

 

[RonD]

I found two new 16v 47uF caps in my parts boxes, but no 63v 10uF, found a local supplier that lists them but I have to buy TEN of them!
$1.75, WTF..................a real waste of $1.50

 

[1990RangerinSK]

Capacitors do have an unknown lifespan... that would definitely do it.

We had a Windows XP computer at work that crapped out a few months ago, turns out a few capacitors on the motherboard went out, you can't just buy motherboards anymore so we scrounged and found a spare motherboard and stole some capacitors... Some software is proprietary and expensive to replace... just today got a replacement computer and the $800 software that made that computer special...

Yes, actually you can. Amazon has a selection of them. The question would be whether or not the board would fit your case.

 

[RonD]

OK, grounds were fine at PCM

New caps are in, there were TWO that were bad, leaking
PCM is back in and it started right up
Drove it for 20min and ran fine

happy happy

I bought a new tip for my soldering iron so cost me just under $10 to fix this, but hours of aggravation and second guessing

 

[Eddo Rogue]

I love it when a plan comes together...