C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

just bricked my pcm

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Old Nov 17, 2018 | 11:56 AM
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Default just bricked my pcm

I was reprogramming my pcm and the software aborted. Had a charger attached so I dont know what happened.. was reading 14v.

So I read the help section and it said to disconnect battery for 10-15 minutes. While I was waiting I continued reading the help file and it said below this to NOT TURN OFF IGNITION in caps and send a recovery...

I yelled FFFFFFFFFFUUUUUUDGEE! My neighbors probably hate me.

So I wait 10 minutes and try to send and if that fails try a recovery. Neither was good.

I have the battery disconnected again but Im not optimistic.. the car behaves just as the manual stats.. VATS is enabled, the car starts and shuts off.

Im pretty good with electronics.. so if any one has advice let me know.

If all fails.. Im seeing PCM's on ebay for $125 to $400.. how to I choose one that will work? Is it important I get my VIN programmed? Some state I need to remove the knock sensor chip from my pcm and move to new PCM?

Please help.. damn Im annoyed.. Ive programmed this thing dozens and dozens of time.. I was in a rush this time and the damn blower was on inside the car and I suspect that was it even though I had a charger on..

Damn.



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Old Nov 17, 2018 | 12:33 PM
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Originally Posted by barchetta1
I was reprogramming my pcm and the software aborted. Had a charger attached so I dont know what happened.. was reading 14v.

So I read the help section and it said to disconnect battery for 10-15 minutes. While I was waiting I continued reading the help file and it said below this to NOT TURN OFF IGNITION in caps and send a recovery...

I yelled FFFFFFFFFFUUUUUUDGEE! My neighbors probably hate me.

So I wait 10 minutes and try to send and if that fails try a recovery. Neither was good.

I have the battery disconnected again but Im not optimistic.. the car behaves just as the manual stats.. VATS is enabled, the car starts and shuts off.

Im pretty good with electronics.. so if any one has advice let me know.

If all fails.. Im seeing PCM's on ebay for $125 to $400.. how to I choose one that will work? Is it important I get my VIN programmed? Some state I need to remove the knock sensor chip from my pcm and move to new PCM?

Please help.. damn Im annoyed.. Ive programmed this thing dozens and dozens of time.. I was in a rush this time and the damn blower was on inside the car and I suspect that was it even though I had a charger on..

Damn.
What year are you driving friend?


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Old Nov 17, 2018 | 12:52 PM
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Sorry this is a 1996. So its the oddball OBDII pcm
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Old Nov 17, 2018 | 12:54 PM
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Now Ive disconnected the ECM, CCM1, ccm2 and ccm3 fuses.. waited a minuted and now the car starts. Doesnt sound particularly happy though. An OBDII reader wont connect and neither will my jet programmer.. it wont do a PCM restore either.. it tries to unlock the PCM but keeps failing..

also the fans run when I turn the ignition on.. so I disconnected the fan fuse while I try and mitigate.
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Old Nov 17, 2018 | 12:56 PM
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And now I realized my charger was connected the whole time.. so I never disconnected power for 10 minutes. I have my charger wired into the hood lights so its easy to connect and I dont use my hood lights. they are disconnected.. geeeeeeeeez.. such drama.
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Old Nov 17, 2018 | 01:43 PM
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well shutting down power didnt help.. now car wont stay running again. Somehow the fuse sequence I used allowed it to start but I cant figure out what the sequence was or its not working.

I could use some help on resolving this or help getting a new PCM.. should I go aftermarket? Might be too expensive and I have no modifications right now so Im guessing not much benefit.
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Old Nov 17, 2018 | 02:06 PM
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I really hope this works out, but that is some funny chit.
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Old Nov 17, 2018 | 08:16 PM
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Pass key relearn?
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Old Nov 18, 2018 | 08:22 AM
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Originally Posted by 84 4+3
Pass key relearn?
Really good advice. I read up on it went to do it and the security light isnt on. So no joy. Ive come to conclusion that the late 90's flash chips are not great.. so Im working with a vendor to get one with new flash chips installed. I do a lot of putzing with transmission settings and am quite happy with the results thus far.

I found out GM programmed an automatic trans into the grand am code.. I pulled it and am quite happy.. its right on the edge of what the 4l60e can handle. they must have considered an auto grand am or something.
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Old Nov 18, 2018 | 11:59 AM
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I ended up ordering the same part # pcm from garrett tuning. Was most reasonable price where I was ensured it had my vin. Just like the idea that I might not run into an issue down the road. Only reason I can really see for having the same vin #:
  • Your tuner is licensed to your vin
  • You have obdii testing where you live and they check the pcm vin
I'll let the forum know how this works out for anyone who has the bastard 96.

Im going to purchase sockets and flash chips for my PCM but Id need a tech1 tool or something else to send the boot code and VIN.

Yeah, I dug into this deep... what a colossal waste of brain cells.
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Old Nov 18, 2018 | 12:07 PM
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Originally Posted by barchetta1
well shutting down power didnt help.. now car wont stay running again. Somehow the fuse sequence I used allowed it to start but I cant figure out what the sequence was or its not working.

I could use some help on resolving this or help getting a new PCM.. should I go aftermarket? Might be too expensive and I have no modifications right now so Im guessing not much benefit.
If you enjoy DiY'ing your engine/trans parameters why not invest in the Holley dominator? It's really 3 systems in one purchase, so the price tag is understandable. Holley has good customer support and it's a scalable solution if you decide to start upgrading hardware. I think the only downside is that you have to do a little work to keep the optispark, or ditch it all together.
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Old Nov 18, 2018 | 12:17 PM
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Originally Posted by jayjones
If you enjoy DiY'ing your engine/trans parameters why not invest in the Holley dominator? It's really 3 systems in one purchase, so the price tag is understandable. Holley has good customer support and it's a scalable solution if you decide to start upgrading hardware. I think the only downside is that you have to do a little work to keep the optispark, or ditch it all together.

I looked into it. Its a fair amount of work that Im not really at a point to do and Im not ready for the price tag. I think to get the car even drivable it would be hours and hours of time to devote to it. So for under $200 Im hopeful I can get back to where I was. Going to keep in mind though when I end up doing a cam. I will be in deep enough to dig into the optispark at that point and make the needed changes.

I really think my pcm blew its lid.. when I turn the ignition on the optispark is firing and sometime the injectors are even firing.. crazy.. I hope no damage was done down the line.. the car does run though for a short period.. but the map is so far off it just dies.

As I mentioned, the very last time I sent a program it had to resend in the middle of it.. so the warning sign was there that the PCM was about to **** the bed.

I guess im lucky this happened in the garage and not in the middle lane of a freeway.
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Old Nov 18, 2018 | 09:13 PM
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Sorry I'm late to this thread. I wasn't on this site yesterday. Yes, if your fans come one as soon as you turn the key to "RUN" then that is a sure sign you bricked the PCM. FWIW, I purchased a replacement PCM for my 96 about three years ago from http://<a href="http://www.pcmperfor...mance.com/</a>, actually from an eBay listing. Like yours, it came programmed with my VIN, and that was important to me for both of the reasons you noted. It has worked fine, and I've had no trouble using Jet DST to flash new calibration files to it. I wouldn't consider going to an aftermarket ECM unless I was going full-race with the car. As long as I have to have a plug-in emissions test, it's not even really an option anyway. But these 96 PCMs (and actually the 94/95 almost-OBD2 PCMs that preceded them) are quite flexible and adapt to a wide variety of engine mods if you use the Jet suite. And frankly, if I'm going full-race (trailer, no street time and no inspection) with a C4 then it would probably be with an LS swap anyway.
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Old Nov 18, 2018 | 09:30 PM
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Originally Posted by MatthewMiller
Sorry I'm late to this thread. I wasn't on this site yesterday. Yes, if your fans come one as soon as you turn the key to "RUN" then that is a sure sign you bricked the PCM. FWIW, I purchased a replacement PCM for my 96 about three years ago from http://www.pcmperformance.com/, actually from an eBay listing. Like yours, it came programmed with my VIN, and that was important to me for both of the reasons you noted. It has worked fine, and I've had no trouble using Jet DST to flash new calibration files to it. I wouldn't consider going to an aftermarket ECM unless I was going full-race with the car. As long as I have to have a plug-in emissions test, it's not even really an option anyway. But these 96 PCMs (and actually the 94/95 almost-OBD2 PCMs that preceded them) are quite flexible and adapt to a wide variety of engine mods if you use the Jet suite. And frankly, if I'm going full-race (trailer, no street time and no inspection) with a C4 then it would probably be with an LS swap anyway.
Im onboard with everything you said. I used to SCCA race and I know the slippery slope to performance mods well. Thanks for the info, I feel good about the decision I made.
The Jet DST has a really bad reputation but I think its without merit. It doesnt take much to research the plethora of settings available.

The only setting Ive failed to find and perhaps its not there is a method to make the transmission behave exactly as it does in position "2" position when its in OD or D position. In the "2" position the tcc stays locked when the throttle is lifted. If anyone has any information pertaining to this Id appreciate it. Ive been able to keep the TCC locked to a certain extent but it seems to release early as RPM's drop.

I hope this thread helps someone else who finds his or her self in the position of a bricked PCM.

EDIT: I didnt mean downshifts.. I edited this to say when the throttle is lifted.

Last edited by barchetta1; Nov 18, 2018 at 09:33 PM.
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Old Nov 18, 2018 | 10:57 PM
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Originally Posted by barchetta1
The Jet DST has a really bad reputation but I think its without merit. It doesnt take much to research the plethora of settings available.
Interesting about the reputation, because it's literally just the OBD2 version of Tunercat. I'm not sure why anyone would have a complaint about it. Unfortunately, I can't help you with the transmission calibration you're looking for. My car is a ZF6 so I get to ignore that plethora of tables and switches! But I would probably want to the same change you are talking about if I had an auto. It might be worth looking for any forums for any cars/trucks that have threads on tuning 1994/5 4L60 transmissions with Tunercat. If you find it for Tunercat it's most likely going to have the same or similar table in Jet DST.
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Old Dec 16, 2018 | 02:52 PM
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just to update this.. I received a new pcm. 1. the website price was wrong and they wouldnt stand behind their mistake. They wanted $45 more. I negotiated and bought but wasnt happy.

2. While it worked fine and I sent my last tune to it with my DST, in the 2nd reprogram it toasted the pcm.

3. I bought sockets, good solder iron, air desolder tool and flash programmer and fixed both my PCMs and wont be looking back.

I reused my flash chips but have new chips on the way from the motherland (china)

EDIT: Im fairly confident now the reason for my program problems was a new china charger I bought that wont keep up when the ignition is on. It wont keep it at 12.4v. Im not particularly fond of china all around... but we made them, now we have to live with them until we fix it.

Last edited by barchetta1; Dec 16, 2018 at 02:54 PM.
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Old Dec 16, 2018 | 03:01 PM
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Originally Posted by barchetta1
EDIT: Im fairly confident now the reason for my program problems was a new china charger I bought that wont keep up when the ignition is on. It wont keep it at 12.4v. Im not particularly fond of china all around... but we made them, now we have to live with them until we fix it.

Pro tip: Don’t buy a generic cheap power supply. There is a reason why they are cheap.
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To just bricked my pcm

Old Feb 23, 2020 | 03:32 PM
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Originally Posted by barchetta1
just to update this.. I received a new pcm. 1. the website price was wrong and they wouldnt stand behind their mistake. They wanted $45 more. I negotiated and bought but wasnt happy.

2. While it worked fine and I sent my last tune to it with my DST, in the 2nd reprogram it toasted the pcm.

3. I bought sockets, good solder iron, air desolder tool and flash programmer and fixed both my PCMs and wont be looking back.

I reused my flash chips but have new chips on the way from the motherland (china)

EDIT: Im fairly confident now the reason for my program problems was a new china charger I bought that wont keep up when the ignition is on. It wont keep it at 12.4v. Im not particularly fond of china all around... but we made them, now we have to live with them until we fix it.
So I just bricked mine too. Actually, the flash tool just crashed in the middle of reprograming with no indication of why. I had battery charger on in boost mode and I've flashed about a dozen times with no issue but today the flash tool just quit mid program. Sooooo care to share some details on how you fixed yours? Sockets, chips etc?
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Old Feb 23, 2020 | 03:55 PM
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Originally Posted by jayjones
So I just bricked mine too. Actually, the flash tool just crashed in the middle of reprograming with no indication of why. I had battery charger on in boost mode and I've flashed about a dozen times with no issue but today the flash tool just quit mid program. Sooooo care to share some details on how you fixed yours? Sockets, chips etc?
To recover without buying a new ECM is quite involved. I wouldnt recommened it unless you are stubborn like me and dont want to risk cooking another one, which is what happened to me if I remember right.

In a nutshell you need:
Sockets (2 per ecu)
Id recommened 2 new flash chips because I feel like they get worn out.. mine was fine for a few dozen writes then smoked. You could and I did rewrite over my old ones but replaced with new once I received from china.
hot Air desolder tool
good quality solder and solder iron with adjustable heat
high powered magnifying glasses to see the small solder joints
super high quality flux
You will need to source the factory bin files for your year
Prom burner
laptop
DeOxit cleaner
Flux remover
Multimeter to test your solder connections on each socket
Flash chip removal tool (removes from socket)

hours and hours of learning how to make it all happen.

I would do a complete write up but I dont see that enough people would take the time to do this to make it worth my time to do the write up, source everything etc.

I have a 96 ecu I would sell with sockets and chips programmed but it only will work for 96 yr. If interested PM me, but you might not like the price I want as I have many hours into this and would prefer keeping it on my shelf rather than sell it cheap. Which is why I dont have it listed for sale.. but since Im a bleeding heart Id sell it to get someone out of a bind. It is in kind of a crappy shell but can easily be moved to a new (your old) shell so the numbers all match. You can use your tuner to write your VIN to it but it is not necessary.

I could also do yours but youd have to give me a little time to dig out some things from storage. Quite frankly its such a pain Id rather not lol.. its a lot of work to solder in the sockets. You are like the 2nd person to ask me about this so not much demand out there.. but it does happen and you have to just suck it up and buy a new one or do what I did. I saw a really cheap on for 96 on ebay last month and even posted it here but no one responded..

Quite frankly, time is money, just buy a new one on flea bay and be done with it.

good luck.
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Old Feb 23, 2020 | 04:29 PM
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Originally Posted by barchetta1
To recover without buying a new ECM is quite involved. I wouldnt recommened it unless you are stubborn like me and dont want to risk cooking another one, which is what happened to me if I remember right.

In a nutshell you need:
Sockets (2 per ecu)
Id recommened 2 new flash chips because I feel like they get worn out.. mine was fine for a few dozen writes then smoked. You could and I did rewrite over my old ones but replaced with new once I received from china.
hot Air desolder tool
good quality solder and solder iron with adjustable heat
high powered magnifying glasses to see the small solder joints
super high quality flux
You will need to source the factory bin files for your year
Prom burner
laptop
DeOxit cleaner
Flux remover
Multimeter to test your solder connections on each socket
Flash chip removal tool (removes from socket)

hours and hours of learning how to make it all happen.

I would do a complete write up but I dont see that enough people would take the time to do this to make it worth my time to do the write up, source everything etc.

I have a 96 ecu I would sell with sockets and chips programmed but it only will work for 96 yr. If interested PM me, but you might not like the price I want as I have many hours into this and would prefer keeping it on my shelf rather than sell it cheap. Which is why I dont have it listed for sale.. but since Im a bleeding heart Id sell it to get someone out of a bind. It is in kind of a crappy shell but can easily be moved to a new (your old) shell so the numbers all match. You can use your tuner to write your VIN to it but it is not necessary.

I could also do yours but youd have to give me a little time to dig out some things from storage. Quite frankly its such a pain Id rather not lol.. its a lot of work to solder in the sockets. You are like the 2nd person to ask me about this so not much demand out there.. but it does happen and you have to just suck it up and buy a new one or do what I did. I saw a really cheap on for 96 on ebay last month and even posted it here but no one responded..

Quite frankly, time is money, just buy a new one on flea bay and be done with it.

good luck.
Wow you really went down the rabbit hole. Thanks for the explanation, it certainly something I won't attempt. Actually I've been on the fence about converting to a 24x setup and I think this is a sign from the gods.
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