ECM Comaptibility
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Instructor
Joined: Apr 2022
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From: South Texas
ECM Comaptibility
Hello Gents. Given we drive 20yr+ cars, has anyone every had to swap their ECM? From what I've gathered, we don't necessarily have to buy a "corvette/pre-programmed" ecm, but one that is compatible with that model. I bought an ecm from an express van, along with knock sensors for a '95 corvette. But it was to down grade my obd2 back down to obd1. So I didn't pull the trigger on it, instead I would like to keep my obd2. That same site, was only able to guide me towards down grading, but not maintaining the current system installed. Any ideas on how to spot an ecm that I could buy and reprogram, rather than buy a "corvette/pre-programmed" ecm? Thanks
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Instructor
Joined: Apr 2022
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From: South Texas
That's what I'm trying to avoid, the $200-300 bill. I'm looking for a used PCM that I can program with my cars' parameters. I know I can buy one for $50, program it, and be done. But my problem is, figuring out which PCM to buy.
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Instructor
Joined: Apr 2022
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From: South Texas
After looking up numbers, the free market went up
. Even on eBay, but then again, its been almost two years. The numbers for the obd1 pcm that I have is 16188051. I noticed they went up in price too... big time
Le Mans Master
Joined: Aug 2015
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From: St. Charles MO
So yeah, the 96-97 hardware is interchangeable, but how were you planning to reprogram it for free? The software that works for 94/95 PCMs does not work on the 96/97 PCMs, unfortunately; and the software that does work on the later units is expensive.
FWIW, the 94/95 PCMs plug right in and work fine on 96 C4s. The only small issue is that your DIC will periodically show the "SYS" error code, even though all the actual engine functions work fine. Well, that and the fact that you wouldn't be able to pass an emissions inspection by plugging the car into a state database like they do where I live (that varies from state to state and even by county). The advantage of the earlier PCMs is that software to edit and flash calibrations to them is cheap or even free. Also, if you are able to do these edits and uploads, you can turn your knock sensors completely off so that you wouldn't even have to worry about swapping them out (which can be a PITA if they are tight in the block, plus you'll lose all your coolant).
FWIW, the 94/95 PCMs plug right in and work fine on 96 C4s. The only small issue is that your DIC will periodically show the "SYS" error code, even though all the actual engine functions work fine. Well, that and the fact that you wouldn't be able to pass an emissions inspection by plugging the car into a state database like they do where I live (that varies from state to state and even by county). The advantage of the earlier PCMs is that software to edit and flash calibrations to them is cheap or even free. Also, if you are able to do these edits and uploads, you can turn your knock sensors completely off so that you wouldn't even have to worry about swapping them out (which can be a PITA if they are tight in the block, plus you'll lose all your coolant).
Safety Car
Joined: Jun 2010
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I believe he is wanting a base tune and you can do that with access to a Tech2. Anything beyond will require the specific programming tool.
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Instructor
Joined: Apr 2022
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From: South Texas
Programming isn’t an issue. I have the mongoose gm obd2, datacat’s for both obd1 & 2, and a jet dst. Plus I have various other software to use as well. And sadly, hp tuners go only as far as ‘97. On the diagnostic terminal. I understand you can short 4 & 12 together, causing the car to go into diagnostic mode. With that in mind, are the fans supposed to come on, like the earlier C4s? If so, mines didn’t.
Also, pcm for less quoted a new pcm with tune for $600
Also, pcm for less quoted a new pcm with tune for $600
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Le Mans Master
Joined: Aug 2015
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From: St. Charles MO
I understand you can short 4 & 12 together, causing the car to go into diagnostic mode. With that in mind, are the fans supposed to come on, like the earlier C4s? If so, mines didn’t.
Racer
Joined: Sep 2001
Posts: 365
Likes: 93
From: Chesterfield VA
.? You can’t custom program anything with a Tech2 and correct me isn’t a mongoose cable just a communication device like the GM MDI. That means it loads in factory calibrations only. PCMs for all C4’s is a pita but it’s what you get with a 30 year old car.
Le Mans Master
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From: St. Charles MO
To the OP (TheKodiak): I just re-read your original post and realized this is for a 95 Corvette? If so, you don't have OBD2 on that car. Only the 96s had that. Even if you could install a 96 OBD2 PCM and make it work (I'm not sure), the engine lacks the crank sensor and probably the proper O2 sensor package to make any of the OBD2 functions work properly. I can't think of a good reason for anyone to want the OBD2 "upgrade" anyway. It doesn't enhance performance in any way at all - it just enables more self-diagnosing of DTCs. You should just run any V8 94/95 PCM and use Datacat to move your stock 95 calibration file over to the new one.
Last edited by MatthewMiller; Dec 28, 2023 at 06:53 PM.
Racer
Joined: Sep 2001
Posts: 365
Likes: 93
From: Chesterfield VA
I think he isn't trying to do a custom tune, but rather just transfer his stock calibration file to a new PCM. If it's a 96, then the Jet DST suite he has will easily do that and if it's a 94/95 then then Datacat will. As ChumpVette wrote, the Tech 2 would do that also.
To the OP (TheKodiak): I just re-read your original post and realized this is for a 95 Corvette? If so, don't have OBD2 on that car. Only the 96s had that. Even if you could install a 96 OBD2 PCM and make it work (I'm not sure), the engine lacks the crank sensor and probably the proper O2 sensor package to make any of the OBD2 functions work properly. I can't think of a good reason for anyone to want the OBD2 "upgrade" anyway. It doesn't enhance performance in any way at all - it just enables more self-diagnosing of DTCs. You should just run any V8 94/95 PCM and use Datacat to move your stock 95 calibration file over to the new one.
To the OP (TheKodiak): I just re-read your original post and realized this is for a 95 Corvette? If so, don't have OBD2 on that car. Only the 96s had that. Even if you could install a 96 OBD2 PCM and make it work (I'm not sure), the engine lacks the crank sensor and probably the proper O2 sensor package to make any of the OBD2 functions work properly. I can't think of a good reason for anyone to want the OBD2 "upgrade" anyway. It doesn't enhance performance in any way at all - it just enables more self-diagnosing of DTCs. You should just run any V8 94/95 PCM and use Datacat to move your stock 95 calibration file over to the new one.
Thread Starter
Instructor
Joined: Apr 2022
Posts: 187
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From: South Texas
I think he isn't trying to do a custom tune, but rather just transfer his stock calibration file to a new PCM. If it's a 96, then the Jet DST suite he has will easily do that and if it's a 94/95 then then Datacat will. As ChumpVette wrote, the Tech 2 would do that also.
To the OP (TheKodiak): I just re-read your original post and realized this is for a 95 Corvette? If so, you don't have OBD2 on that car. Only the 96s had that. Even if you could install a 96 OBD2 PCM and make it work (I'm not sure), the engine lacks the crank sensor and probably the proper O2 sensor package to make any of the OBD2 functions work properly. I can't think of a good reason for anyone to want the OBD2 "upgrade" anyway. It doesn't enhance performance in any way at all - it just enables more self-diagnosing of DTCs. You should just run any V8 94/95 PCM and use Datacat to move your stock 95 calibration file over to the new one.
To the OP (TheKodiak): I just re-read your original post and realized this is for a 95 Corvette? If so, you don't have OBD2 on that car. Only the 96s had that. Even if you could install a 96 OBD2 PCM and make it work (I'm not sure), the engine lacks the crank sensor and probably the proper O2 sensor package to make any of the OBD2 functions work properly. I can't think of a good reason for anyone to want the OBD2 "upgrade" anyway. It doesn't enhance performance in any way at all - it just enables more self-diagnosing of DTCs. You should just run any V8 94/95 PCM and use Datacat to move your stock 95 calibration file over to the new one.
Negative ghost rider, it's a 1996. I have the software for a stock 1995, which what I was going to do initially. Install the PCM, swap knock sensors, program and go. Of course, only because the '96 is the bastard child lol. But I got the DST instead. Now the computer won't send a signal to the cooling fans. Which is the reason for the swap. Thank you fellas for chiming in.
Le Mans Master
Joined: Aug 2015
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From: St. Charles MO
Racer
Joined: Sep 2001
Posts: 365
Likes: 93
From: Chesterfield VA
I would go back to the fan relays and make sure you have batt power to them and keyed 12v. The pcm will send the ground so with the key on ground that wire and see if they come on. That will let you know everything is working and it’s either a wiring issue between the relay and PCM or the PCM. I can program the PCM if needed.
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Instructor
Joined: Apr 2022
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From: South Texas
Here's another strange thing that has happened to this vette. The PO of the vette had it tuned one time. Turned out, that the Tuner locked the PCM. Not knowing that, I went ahead and got a jet dst. When I tried to read the PCM, my xp os laptop froze, the dash lit up like a christmas tree, and both fans started screaming... so I turned it back off. Unplugged the laptop, and turned the key back on, just to hear/see the same christmas song. I later learned that I bricked the computer. I disconnected the battery and called it a day. To make a long story short, a buddy of mine (DRCook), got me a copy of his '96 bin, and with about 48hrs of no juice. I went back to the car and connected the battery. Went through the motions of "reading" the pcm. Turned the key to find the pcm was no longer bricked. So I forced programmed the computer, and I've been making adjustments since then. No issues until now lol
Le Mans Master
Joined: Aug 2015
Posts: 6,091
Likes: 1,972
From: St. Charles MO
Here's another strange thing that has happened to this vette. The PO of the vette had it tuned one time. Turned out, that the Tuner locked the PCM. Not knowing that, I went ahead and got a jet dst. When I tried to read the PCM, my xp os laptop froze, the dash lit up like a christmas tree, and both fans started screaming... so I turned it back off. Unplugged the laptop, and turned the key back on, just to hear/see the same christmas song. I later learned that I bricked the computer. I disconnected the battery and called it a day. To make a long story short, a buddy of mine (DRCook), got me a copy of his '96 bin, and with about 48hrs of no juice. I went back to the car and connected the battery. Went through the motions of "reading" the pcm. Turned the key to find the pcm was no longer bricked. So I forced programmed the computer, and I've been making adjustments since then. No issues until now lol