Eeprom error problem (Page 1/2)
Elevatormechanic88 JUN 16, 09:15 PM
I have a 1984 fiero with a 2.5 L and it’s running rough with an EEPROM fault indicated . Do I need an updated EEPROM or is there any other fix/repair for this problem
IMSA GT JUN 16, 09:33 PM
Code was 51?
Elevatormechanic88 JUN 16, 11:25 PM
Yes it is code 51
jelly2m8 JUN 17, 02:21 AM
At this stage in the cars life I would simply look for an Eprom or ECM from an 84 that ran well, back in the early 90's I had an Eprom failure and even back them GM had 6 or 7 Eprom updates for the 84's
sanderson231 JUN 17, 11:30 AM
When the EPROM was programmed a check sum value was stored at a certain memory address. The check sum is just the summation of all the 1's and 0's for all memory locations. If the ECM does not read the expected value for the checksum, it means that something has corrupted the memory. I believe that when a a code 51 is present the ECM ignores the EPROM and the vehicle runs on hard-wired back up circuitry. It is possible is install a new EPROM and program it for your vehicle but the EPROM is soldered in and takes some skill to do it. As mentioned in a previous post the quickest and easiest solution is to find used ECM with the correct EPROM.

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formerly known as sanderson
1984 Quad 4
1886 SE 2.8L
1988 4.9L Cadillac
1988 3800 Supercharged

[This message has been edited by sanderson231 (edited 06-18-2023).]

82-T/A [At Work] JUN 17, 12:22 PM

quote
Originally posted by Elevatormechanic88:

I have a 1984 fiero with a 2.5 L and it’s running rough with an EEPROM fault indicated . Do I need an updated EEPROM or is there any other fix/repair for this problem




Hi, is it an automatic? I have an 84 Automatic complete ECM available if you want it.

Note: I also owe someone else an 84 manual (which is in storage). But like with the other individual, if you want it, I'm happy to give it to you for free... I don't want anything for it. But I highly value my time. So... if you can mail me a shipping label w/ postage for a thin medium-sized Priority U.S. Mail box, I will send it out to you for free. I don't know what shipping will be from the U.S. to Canada, but if you want to mail me a shipping label, the ECM is yours.

This is it. I cannot confirm if it's working, but these generally don't go bad, it's usually everything else. Back in the day when I'd see a Fiero in the junkyard, these were $10 a piece, so I used to just snatch them up if the car was likely going to get crushed that day. This one might have come as a spare with another car I purchased too. Let me know... I'll PM you my address.



The benefit to me is that these don't go to waste and it helps keep a Fiero on the road.
Mickey_Moose JUN 19, 04:09 PM

EPROM is not soldered in - it is in a socket (well actually it is in a carrier which is then inserted into the socket - no soldering required).

That being said you need the equipment to erase and reprogram it and if you do not have this equipment it is easier to just find another ECM (lots of 84 out there).

Just make sure you get one that matches your car (84 and automatic or standard transmission) as the code is different between the different transmissions.
Elevatormechanic88 JUN 19, 07:18 PM
Thanks for your kind offer but my 1984 fiero is a standard
Elevatormechanic88 JUN 19, 07:23 PM
Appreciate your help everyone but it looks like I’m going to have to hunt in the area for the EEPROM .
Off to the wreckers and back fields I go
shemdogg JUN 19, 09:54 PM
Hey man some of the cats on here can program that or send u a new one. Someone posted in the mall recently w some swappable chip for the ecm., prolly knows what u need. Hit up handymanpat or some of the other guys in the mall section that have cars to part out. Someone here has what u need for sure!

shem