Issues with your PCM??
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 760
Likes: 1
From: N.W. Arkansas
Issues with your PCM??
So, on my 95 vette they have traced problem to having a bad cpu in the PCM,,, non fixable they tell me,, ( the experts),,,, anyone ever had issues with theirs??? thanks rj
Le Mans Master
Joined: Aug 2015
Posts: 6,102
Likes: 1,981
From: St. Charles MO
It's possible to have issues. They aren't incredibly expensive to replace, but you need to have it set up for your VIN. You can also have yours actually checked and repaired (if it really even needs to be replaced). But I certainly hope the "experts" you have working on this car have really run through the full diagnostic procedures to narrow this down to the PCM! The factory service manual has the full rundown in it.
Team Owner
Joined: Sep 2003
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You haven't mentioned any recent issues so maybe you pass on just what it is that took you to "the experts"? Runs but not well, doesn't run, DTC, crank/no crank etc. You might mention A4 or M6 also.
It certainly wouldn't be out of the question to need a PCM -
It's difficult to tell if your reference "the experts" is sarcasm or not.1st inclination I'd think is yes! Have "the experts" done you well in the past? A 1st experience?
Do "the experts" have a sign on the building, no building but maybe a big tree?
Last edited by WVZR-1; Dec 29, 2017 at 06:41 AM.
Race Director
Joined: Oct 2008
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From: Lansing MI
These PCMs are pretty reliable and I would be surprised if its the root cause of the cars trouble.
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 760
Likes: 1
From: N.W. Arkansas
my experts are the local chevy dealer,,, i have first gear only and reverse with stuck zero on the speedo dash read display,,,, chevy tech replaced the vss but didnt fix problem,,,, so, he traced it to the pcm,, I sent the pcm to a repair shop and they said its the cpu inside the pcm was shot and unfixable and unreplaceable,, he refunded my money too,, so honest there,,,,, so,, someone said these are easy to find,, they are like a unicorn,,, someone else said they got one from autozone, i tried there and other parts stores and no luck,,,, found one in OHIO and should be here on tuesday,,, but who knows if its gonna work,,??? guess we'll see,, rj
Le Mans Master
Joined: Aug 2015
Posts: 6,102
Likes: 1,981
From: St. Charles MO
my experts are the local chevy dealer,,, i have first gear only and reverse with stuck zero on the speedo dash read display,,,, chevy tech replaced the vss but didnt fix problem,,,, so, he traced it to the pcm,, I sent the pcm to a repair shop and they said its the cpu inside the pcm was shot and unfixable and unreplaceable,, he refunded my money too,, so honest there,,,,, so,, someone said these are easy to find,, they are like a unicorn,,, someone else said they got one from autozone, i tried there and other parts stores and no luck,,,, found one in OHIO and should be here on tuesday,,, but who knows if its gonna work,,??? guess we'll see,, rj
As for the replacement, didn't the ECM repair place offer to repair it or send you a new reman part? I was able to find a good new one on Ebay from a seller named vectorbundle for $245 in 2015. But maybe things are scarcer now - I don't know. I would expect SIA Electronics could repair yours for you, as an alternative. I hope the one you have ordered is good, but if not there are probably options. Let us know how it goes, and if you need more ideas for a source of new ECMs.
Last edited by MatthewMiller; Jan 1, 2018 at 12:15 AM.
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Le Mans Master
Joined: Aug 2015
Posts: 6,102
Likes: 1,981
From: St. Charles MO
It does. The VSS first sends its analog signal to the PCM, which converts it into a digital signal. The PCM also uses the speed signal for certain running parameters, such as deceleration fuel cutoff and the way to handle drop-throttle idle while the car rolls. If you unplug the VSS, the engine will probably stall when you lift off while rolling (at least in a manual-trans car). Anyway, the PCM then passes along the digital speed signal to the tach, cruise module. and one or two other things (I forget). This is true for 94-96 cars, at least. I don't know if it's true for earlier PCMs.
Race Director
Joined: Oct 2008
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From: Lansing MI
Real interesting footnote on steps 9&10 about selective ride control. Easy place for someone to blunder I guess. Its not represented on the wiring schematic. Not an excuse for diagnosing this wrong if that turns out to be the case.
Last edited by PatternDayTrader; Jan 1, 2018 at 11:28 AM.
Team Owner
Joined: Sep 2003
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my experts are the local chevy dealer,,, i have first gear only and reverse with stuck zero on the speedo dash read display,,,, chevy tech replaced the vss but didnt fix problem,,,, so, he traced it to the pcm,, I sent the pcm to a repair shop and they said its the cpu inside the pcm was shot and unfixable and unreplaceable,, he refunded my money too,, so honest there,,,,, so,, someone said these are easy to find,, they are like a unicorn,,, someone else said they got one from autozone, i tried there and other parts stores and no luck,,,, found one in OHIO and should be here on tuesday,,, but who knows if its gonna work,,??? guess we'll see,, rj
Did you send the PCM or did the dealer?
Here's what I understand from some information that was shared with me by a dealer. The dealer can submit 'some' ECM, PCM, BCM, CCM for repair through them. You surrender yours and it's either repaired or returned as "non-repairable" - your statement hints that YOU did this NOT the dealer, so I'd think the repair facility used if it wasn't through the dealer(your expert) then maybe didn't have access to needed parts, they maybe just do resolder issues etc. You should talk to the dealer parts dept.
The list that I've had for sometime has your PCM on it.
The program is called R & R Exchange for repair. I've done a BCM using the program.
Take this tag/form to the dealer - using this they should be able to figure out NEXT.
I've been meaning to compile a C4 list for a while but I've just been lacking the time.
***Note on the tag APPLICATION INFORMATION It mentions that for FLASH PCM (yours) they want you to supply VIN & Trans information, perhaps hinting that it might be returned -"ready to install".
Last edited by WVZR-1; Jan 1, 2018 at 01:25 PM.
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 760
Likes: 1
From: N.W. Arkansas
Yes, I sent the original PCM to G7 car computers in NEW YORK St.... 175 bucks for fix with lifetime warranty.... so I get a call from him and he said its the CPU,, which is un-fixable or non replaceable, so he refunded my money and shipped it back.... thus my start in a search for a new/used PCM.... Found one on Ebay and got it installed yesterday,, and YEA,,, problem solved,, it now upshifts correctly, it now shows my speed and runs great again,, thanks all for your input,,,, rj
Team Owner
Joined: Sep 2003
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Yes, I sent the original PCM to G7 car computers in NEW YORK St.... 175 bucks for fix with lifetime warranty.... so I get a call from him and he said its the CPU,, which is un-fixable or non replaceable, so he refunded my money and shipped it back.... thus my start in a search for a new/used PCM.... Found one on Ebay and got it installed yesterday,, and YEA,,, problem solved,, it now upshifts correctly, it now shows my speed and runs great again,, thanks all for your input,,,, rj
What would be interesting, actually of considerable value to do would be take the known bad PCM to the dealer who it seems you've had an experience with and have them submit it for repair using the GM program I mentioned. You'd have a backup or an easy resale piece. It would also maybe add credibility to what can and can't be repaired by whom. If 'non-repairable' I understand it should be returned with no charges.
If my notes are correct the part# for the R&R would be 19240487.
This would be a link the dealer could maybe relate to:
16181333 > 88961148 > 19240487
It would make for at least an interesting conversation with the dealer.
You're just running the 'program' that was on the eBay PCM or what?
Last edited by WVZR-1; Jan 3, 2018 at 08:24 AM.
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 760
Likes: 1
From: N.W. Arkansas
I bought it from Spareecm off ebay,,, he wanted my VIN # and he programmed that all in for me with all the programming needed to be up and running without taking to chevy dealer for anything,, just plug and play with about a 10 min. learn cycle of the security on the car,, the rest comes from driving he said,,,, just got in from a nice drive,, all is great cept my fuel sender unit is showing full all the time,, (started before the PCM issues) need to fix that next