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what exactly does pcm control? help please

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Old Sep 23, 2008 | 09:40 AM
  #1  
mt250's Avatar
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From: new orleans, la
Cool what exactly does pcm control? help please

So i was driving my truck from new orleans to memphis, tn., when i suddenly noticed it was not charging, a/c would no longer kick in, overdrive stopped engaging, etc. Took in and could get no codes off computer (fried)and the guy found i had two "weaK" grounds which were repaired. Got a rebuilt computer (autopart.com=bad customer service) and installed it myself (yes unhooked battery 1st). Now i have a/c and charging sys. back but no overdrive (or is it lock up?) or cruise control(have checked the pin out continutity via this site seems ok at c/c switch at steering wheel. could i have gotten a bum computer or maybe one for a truck that has no overdrive and c/c? anyone have any ideas?

I've looked in the sticky about the POT. install. but am not sure where the o/d switch i need to ground is located on transmission or how to get c/c back anyway. i gotta get back and would prefer to do it in o/d and no foot on pedal..

electral stuff drives me nutz

oh yea the new computer humms. is that normal?
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Old Sep 23, 2008 | 10:25 AM
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as an after thought the speedo quit working also could this be the culprit? the vss is new but no speedo. maybe the little plastic gear in the transmission is worn, but would that make the o/d and c/c not function?
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Old Sep 23, 2008 | 11:05 AM
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yes. if you have no speedo then you won't have lock up or overdrive. Your overdrive and lock up needs a vechile speed to know when to lock up and to engage so if its missing that input then it doesn't know when to engage.
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Old Sep 23, 2008 | 12:01 PM
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I thought first gens didn't have a lockup transmission
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Old Sep 23, 2008 | 12:24 PM
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thanks dog. what about the cruise control would that be affected also. I just tried to ground the o/d solenoid but got nothin.i grounde the wire that does not have 12v come from it is that the right way to do it.
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Old Sep 23, 2008 | 03:54 PM
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Gotta get the speedo working. Check the VSS drive.
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Old Sep 23, 2008 | 06:17 PM
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got it narrowed down i think>?.
took off vss, gearing apparatus, then pulled the drive gear out.
stuck my pinky in the hole and was able to rotate the worm type gear while in park.
surely this is not correct and that's why the speedo isn't getting a signal.
I dropped the shaft and tightened that nut (1 5/16") pretty dang tight
the worm gear still spins freely around shaft. That worm gear is yellow.

So how on earth do you chang it (BESIDES JUST GOING AT THE BOLTS AROUND THAT DRIVE GEAR HOUSING)
is it better to have a shop do it? how much?

anyone

thanks a heap,
mt
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Old Oct 6, 2008 | 09:09 AM
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From: beaumont, tx
This sounds exactly like the problem I am having with my truck, no od no charge no ac clutch. My question is this, if I have had an internal regulator installed on my alternator, can I plug in a new computer? Or will it fry anything?
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Old Oct 6, 2008 | 09:25 AM
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its the pcm, my truck did exactly the same thing
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Old Oct 6, 2008 | 11:00 AM
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i don't know if the external regulator will fry anything. What i have read is the computer doesn't care if the alternator is regulated by an external (to the computer) voltage regulator. with my truck i just hooked up an exterernal box and just bent the computer connection tabs at the altenator back.

My biggest problem from all the trouble i had was wire chaffing where the fire wall and drivers side floor pan are seamed.
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Old Oct 6, 2008 | 03:14 PM
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From: beaumont, tx
wheres a good place to get a computer without getting reamed?
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Old Oct 6, 2008 | 08:41 PM
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I bought mine thru a local advanced auto parts, about $200, took a few days to get it.
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Old Oct 8, 2008 | 06:01 PM
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From: new orleans, la
NEW - dealership in memphis, tn wants $220 + tax(.09) + shipping

REMANUFACTURED - autopart.com was 160.00 + 12.00 shipping (4lbs.) then you gotta retun ship the core (70.00) for another 12.00 (but their customer service is poor) it took em 10 days to get it to me because theyshipped it from 1 warehouse to another to another then to me. first guy lied about it, 2nd guy backed him up and manager said oh well you'll get it (in another 5 days!?!)
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