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I've got a 1991 6-speed, and am needing a new PROM. I've got a cylinder select code, sys flashing on the dash, and module 4 says err when I run the diagnostic thing.
What I'm wondering is how I would find one that works?
Do I need to replace the memcal as well, or should I just get the PROM? Also mine has a sticker that says AXCN mod 4 on it (picture attached), causing me to think it might be aftermarket. Would just replacing this chip work possibly?
I'm not sure, but it looks like the eprom on mine is elevated higher above the rest of the unit than the pictures I have seen. Is this because of an aftermarket chip? Is it stuck on top of the stock eprom?
I don't really understand this unit and it's got me very confused. Usually I can get a pretty good idea of what's going on but mine just doesn't look like any of the examples I have seen.
Thanks!
Here's another picture of it that might be easier to see. The ECM I'm using is a reman from blue streak, I got it about 2 months ago. Was running great until it suddenly died while driving and wouldn't start again.
I've got a 1991 6-speed, and am needing a new PROM. I've got a cylinder select code, sys flashing on the dash, and module 4 says err when I run the diagnostic thing.
What I'm wondering is how I would find one that works?
Do I need to replace the memcal as well, or should I just get the PROM? Also mine has a sticker that says AXCN mod 4 on it (picture attached), causing me to think it might be aftermarket. Would just replacing this chip work possibly?
I'm not sure, but it looks like the eprom on mine is elevated higher above the rest of the unit than the pictures I have seen. Is this because of an aftermarket chip? Is it stuck on top of the stock eprom?
I don't really understand this unit and it's got me very confused. Usually I can get a pretty good idea of what's going on but mine just doesn't look like any of the examples I have seen.
Thanks!
You just discovered. The PO or someone versed.
Actually DEsoldered the factory eprom.
Modified. Hence homemade sticker Mod4
Updated with factory a UV burner.
The 2nd pic posted afterward
is a ZIF socket. The safest.
Installing/ removing the eprom
Hence higher than factory.
That eprom can be removed and installed any time.
With proper care.
Yet. I believe that is still a eprom. If correct do NOT pull that sticker. UV light sources. Can and will erase.
Last edited by THE 383 admiral; Oct 6, 2022 at 12:07 AM.
Alright that clears that up quite a bit. I’ll do some more research and figure out if I can get it reprogrammed or something. Or maybe switch to the eeprom like you mentioned.
If you gently rub across that sticker.
If you feel an indentation. That will confirm. The UV window.
That eprom does not have the typical factory lettering.
From: Liliha Bakery stuffing my face with coco puffs!
I can say with 100% certainty the chip/PROM is in backwards. I'm surprised that it even runs like that. Hope it didn't get damaged while running it that way. The little notch at the end of the PROM designates pin 1 and needs to be in the same orientation as the pic courtesy of 85MikeTPI.
Idk if the screw on the end of your PROM carrier releases the PROM, it might be just 1/4 turn to release tension on the pins and it'll pop out. Be gentle.
If it has the clear window under the sticker, yes you can leave it out in the sun and it'll erase but I've left them out for about week and sometimes they don't erase completely. There are devices that emit UV light and that erases it within 30-45 minutes. It can be time consuming bc after cooking in the UV eraser, recommend to do a blank check and if it fails, pop it back in the UV eraser for another 30 minutes. After a successful erase, write to the blank PROM and pray it verifies. If it doesn't go back to erasing. Last time I've done this, success rate 1 in 3 tries. Once I went to EEPROMs, I've never gone back as it's about the same effort copying a file to a USB drive.
Last edited by stew86MCSS396; Oct 6, 2022 at 05:02 AM.
Yes that screw does release the PROM, I removed it and didn’t pay attention to which direction it was facing when I put it back, so the car has never run with the prom facing that direction. I’ll fix that now.
What would I need to reprogram the prom? And is there software or something with preset data? I’ve never done any sort of tuning before, the closest thing I’ve done to tuning was read data from tuner pro.
From: Liliha Bakery stuffing my face with coco puffs!
Good news on the EPROM orientation!!! Is your C4 stock? I would return to stock if it is but your mod v4 tells me otherwise. I'm just wondering what the nature of the mod v4 is and what made it necessary. We can discuss that at a later time. I commend you for wanting to do this as most shy away from it. Anyhoo...since you have a memcal that's been modified to facilitate removing the EPROM, then you would just need some blank EEPROMs and a Burner. You can shop around but Moates has everything you need. Be advised that their Burner only does the EEPROMs and won't flash the UV erase EPROMs. Burner software from Moates is called Flash and Burn that you can download from their site. http://www.moates.net/burn2-chip-pro....html?cPath=94 http://www.moates.net/c2-sst-27sf512....html?cPath=26
There's places you can download the binaries aka bin and flash to your blank EEPROMs. Also be advised that the EEPROMs linked, capacity wise are double the size of your OE EPROM so either you bin stack it or start the write at the line address in the middle of the EEPROM. There's instructions on the support page for the BURN2.
Last edited by stew86MCSS396; Oct 6, 2022 at 05:54 PM.
Reason: esl
Is there any benefit to buying the moates gear rather than buying a whole new memcal unit from http://gmeprom.com/index.html?
It doesn't look like I'd be saving much money programming my own and I'd run the risk of messing it up.
From: Liliha Bakery stuffing my face with coco puffs!
Only you can decide. You didn't comment when I mentioned returning to stock. Would you know if the engine is stock? If you know for a fact things were altered that would affect driveability, then I would think it would be of some benefit. I find it hard to believe the ECM keeps going bad since you're on your third one? Maybe your PROM carrier wasn't soldered on good, I'd check continuity of each EPROM pin to the memcal.
Only you can decide. You didn't comment when I mentioned returning to stock. Would you know if the engine is stock? If you know for a fact things were altered that would affect driveability, then I would think it would be of some benefit. I find it hard to believe the ECM keeps going bad since you're on your third one? Maybe your PROM carrier wasn't soldered on good, I'd check continuity of each EPROM pin to the memcal.
the engine is pretty much stock as far as I know, except for an EGR delete and relocated IAT sensor from the previous owner.
This is my second ECM. The first one has something rattling inside and it’s erratic. I was going to buy another when this problem started but got on the track of the PROM before I did.
I’ll see if I can test continuity when I get the chance
'91 PROM questions
