Long story short I'm 99% sure my pcm is bad and then I found a shorted resister in it that goes to pin 17 the self test pin would that effect my ignition /fuel timing? 94 ranger 4.0 4x4 auto

 

Shorted resistor, or shorted capacitor????

 

from what i can tell its pin 17 (self test pin) pulling code still works.... [IMG]<a href="http://s497.photobucket.com/albums/rr332/adamjmerideth/?action=view&amp;current=20120809_230955.jpg" target="_blank"><img src="http://i497.photobucket.com/albums/rr332/adamjmerideth/20120809_230955.jpg" border="0" alt="Photobucket"></a>[/IMG] [IMG][/IMG]

 

Yup its a resistor, but it looks like something has leaked out of the device to the left of it & run down to the lower end of the resistor.

Maybe try using some CRC QD, or IPA on a foam swab to tidy up the deposits & have a look at the part to the left of the resistor, for overheating/leaking something.

The right side edge of the device next to the resistor looks to be melted, so inspect it closely. It has large diameter wires connecting it to the circuit board, so it likely carries a good bit of current, so if it had internal problems it would likely run hot.

 

I agree with pawpaw - it looks to me like the component to the left of the resistor is the culprit - I've seen some electrolytic capacitors leak brown crusty stuff that looks a lot like what's in that picture.

I'm just guessing, but that device might be some sort of electrolytic diode (it looks like a diode to me) and, from the looks of it, something cooked it pretty good... I can't tell if the # on that is T2125 or T212S...

That resistor might be just fine - usually, when a resistor goes bad, they burn up - sometimes you can see a black spot in the middle of the resistor (at least, that's been my experience)...

There's something just to the left of that mystery device - kind of rectangular looking like maybe it's a chip - might want to have a look at that as well as the area around that looks like it got cooked...

 

Note, this is all speculation. I'm just a guy who's wasted hours reading about this crap. I don't pretend to be right.

Would that affect your mileage -- hard to say. The PCM controls timing, injector times, egr, and the idle air control. You could probably check out the timing a bit, and see how it varies with rpm. Won't tell you about how it does when loaded. Injector times would take a scope.

If something suddenly changed, then it's certainly suspect. Although I think that they usually just crap out.

As to your issue:

From the looks of it, that's a 2 K resistor. A little unusual, they're usually 2.2 K. So,it might be a 1%.

It may or may not be shorted. The part next to it that spewed may be in parallel. If it's shorted, it would mask the resistor value.

I suspect that that part may be a zener or a MOV(metal oxide varistor). If you can possibly find some numbers on it, you might be able to find a replacement. Either of those could be there to prevent overvoltage, so they could well have toasted - along with who knows what else.

Folks around here do replace parts on PCMs, usually capacitors. If you can find the parts you need, you might seek some advice in replacing. The holes on the board are plated through, and it takes a little effort sometimes to get parts out cleanly and not rip anything up.

If you do decide for sure that it's your pcm. There used to be a junkyard around here that would sell PCMs from wrecks for around $100. I would imagine that there's one around you as well. Also, there at least used to be remanned pcms available. I suspect that the 'reman' was sometimes just a quick test to see if it worked. Maybe if they were thorough they'd heat and cool it while they tested it.

Good Luck,

hj

 

Well the pcm is off to cardone.... my dad's buddy runs the plant in Philly so he's taking it in and testing it will keep you poasted

 

Will be interesting to hear whats found. I'm running a 1 year old Cardone Ford re-man computer in my 94 3.8L Taurus, no problems so far!!!!