bad PCM?

[Birdman1]

howdy,
How common is it for the PCM to go bad on these trucks? Is there any definitive test to decide if they are bad?

thanks,
pkn

 

[MrShorty]

I wouldn't say that it is common, but it isn't unheard of, either.

The most definitive tests I've heard of are from those who are familiar with solid state circuitry and circuit boards, where they've opened the PCM up and been able to smell and/or see the burnt circuit(s).

Most "by the book" tests for a bad PCM are by process of elimination -- once you've eliminated all other possible causes for the symptoms, then the PCM must be at fault.

 

[chrisgodaddy]

i had a bad pcm it was a NIGHTMARE , ended up costing me $3000

when it goes out, the car wont shift, it will drive very erratic and bumpy from a redlight...so i thought it was the tranny. so i took it to a tranny shop,,.they charged me 2200 for a tranny(which btw runs like crap afterwards so they made the tranny worse) then after 2 weeks they called and said it was the pcm..so they charged me another 800.

then after 2 weeks, the new pcm (which they got from a junkyard) BLEW OUT literally while driving, sounded like a lightbulb blowing out, and the car went dead...the only way i could get home was to unplug the maf sensor and it still rode like crap but atleast i got home

then i took it to another shop, and they said the new pcm blew out (from what they didnt know but they were guessing the new maf from the tranny shop blew out the new pcm) so this shop charges me another 600$

so i spent 3600 for a pcm. what a freakin joke

if your pcm goes out, my advice is to spend about 2000 on a newer explorer (i wish i did that)

 

[rustbucketMI]

What makes you think your PCM is bad?

 

[osteologation]

i had a bad pcm it was a NIGHTMARE , ended up costing me $3000

when it goes out, the car wont shift, it will drive very erratic and bumpy from a redlight...so i thought it was the tranny. so i took it to a tranny shop,,.they charged me 2200 for a tranny(which btw runs like crap afterwards so they made the tranny worse) then after 2 weeks they called and said it was the pcm..so they charged me another 800.

then after 2 weeks, the new pcm (which they got from a junkyard) BLEW OUT literally while driving, sounded like a lightbulb blowing out, and the car went dead...the only way i could get home was to unplug the maf sensor and it still rode like crap but atleast i got home

then i took it to another shop, and they said the new pcm blew out (from what they didnt know but they were guessing the new maf from the tranny shop blew out the new pcm) so this shop charges me another 600$

so i spent 3600 for a pcm. what a freakin joke

if your pcm goes out, my advice is to spend about 2000 on a newer explorer (i wish i did that)

$800 for a PCM, $600 for a maf. Sounds like they seen you coming...

 

[Birdman1]

Our explorer has an erratic idle issue, I have tested lots of components, replaced a couple, and it still does what it does (I have another thread on here about that that no one seems to have any clue where to go next). So I was just curious if there was any way to rule it out.

 

[osteologation]

Our explorer has an erratic idle issue, I have tested lots of components, replaced a couple, and it still does what it does (I have another thread on here about that that no one seems to have any clue where to go next). So I was just curious if there was any way to rule it out.

PCM range from $30 to $40 around here at the junkyard. I've had one go bad before. I couldn't get codes off it tho. And erratic either always on or off fast idle.

 

[Birdman1]

you are saying when yours went bad you had always on or off fast idle?

or you are asking about mine?

 

[osteologation]

you are saying when yours went bad you had always on or off fast idle?

or you are asking about mine?

Mine. It was a crap shoot, either it was on all the time or not at all.

 

[Birdman1]

interesting, not at all meaning super low idle like the IAC is not working? then randomly jumping to 1500 or so?
Right now I have the IAC unplugged, and it runs just hunky-dory, but with a low idle, so you have to sit with it for a minute in the morning until it builds a little heat and will idle. No CEL or anything.
as I said in my other thread I have replaced a few things, I have tested several others, I have tuned it up, it is not throwing any codes, thats why I am at a loss right now, and no one seems to have any idea in the other thread either.
I just wish there was some way to test the PCM before I bother replacing it, they run 50.00 at Pick-N-pull and about 250.00 at the parts store.

 

[osteologation]

you are saying when yours went bad you had always on or off fast idle?

or you are asking about mine?

interesting, not at all meaning super low idle like the IAC is not working? then randomly jumping to 1500 or so?
Right now I have the IAC unplugged, and it runs just hunky-dory, but with a low idle, so you have to sit with it for a minute in the morning until it builds a little heat and will idle. No CEL or anything.
as I said in my other thread I have replaced a few things, I have tested several others, I have tuned it up, it is not throwing any codes, thats why I am at a loss right now, and no one seems to have any idea in the other thread either.
I just wish there was some way to test the PCM before I bother replacing it, they run 50.00 at Pick-N-pull and about 250.00 at the parts store.

No it would have no fast idle for a few days, then the next day it might have fast idle and stay that way till I turned it off.

But the no codes was the clincher for mine.

I wonder, since it is the iac, if the ect sensor may be intermittently sending an erroneous signal. Or a bad connection. It runs fine otherwise(with iac unplugged) and vacuum seems stable?

I would try unplugging one sensor at a time to see if it affects it. I've narrowed other probs down like that especially intermittent ones.
I.e. Unplug maf and drive it around, then plug it in, then unplug tps, o2 etc

Just an idea.