Eeprom error problem (Page 2/2)
jelly2m8 JUN 20, 02:21 AM
It will run fine on an Automatic ECM, may not have a shift light but it will run right.
theogre JUN 20, 08:43 AM
They Don't use EEPROM.

Factory PROM are UV Erase w/ quartz glass or not. Or not means Can't Erase but Program same way 1 time.

PROM Code 51 is very often Not a bad PROM but iffy ECM w/ bad solder joints etc so can't read them.

Get used ECM often have same problem but may get other Bogus Codes or simple won't work when ECM is hot, cold or at all now or soon.

Remove "insulation" on the console that touches and covers front of ECM. ECM get no air to cool w/ that covering the front of it.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

[This message has been edited by theogre (edited 06-20-2023).]

armos JUN 21, 03:42 AM
With the key turned off (no power to the ECM), try pulling the chip and reseating it. It's in a tan colored plastic carrier, it's a 24 pin chip in a 0.6in wide package. If you rock the carrier back and forth lengthwise it will pop loose and bring the chip out with it. Don't rock it too extremely or you could bend a pin (not sure if the carrier prevents that).
Then just plug it back in.
I've had this error pop up a couple times over the years and fixed it by reseating.

Pay attention to the orientation - if you plug it in backwards you'll kill the chip.

If that fails, there's probably people that can program a replacement for you. I *think* the EPROM used in the 1984 ECM is a 2532, but I don't remember where I read that and could be wrong.
sanderson231 JUN 21, 10:11 AM

quote
Originally posted by Mickey_Moose:


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.




But the EPROM is soldered into the carrier. If you are trying to solve the problem by changing the EPROM one option is to find a used EPROM in the carrier. That's plug and play. That said it is probably easier to find a complete used ECM w/PROM.

Alternately a blank EEPROM (electrically erasable) can be installed but that requires soldering and the best way to do it is to install a ZIF socket on the carrier in place of the EPROM. Then changing PROMs is a breeze. The blank EEPROM needs to be programmed. Tunerpro software is free. You also would need to buy or borrow a burner like the Moates Burn2. The .bin file to program the EEPROM may be available to download on gearhead-efi.com. Not easy but can be done.

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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 06-21-2023).]

theogre JUN 21, 01:34 PM
Maybe Removing and replug the chip can work... "dirt" and "rust" often does happen to tinned parts and doing that can clean them. Some plastic safe contact cleaner may help too.

But often not in old ECM because what I said above. Plus many have "coated" boards and the "clear paint" GM used causes problems like lifting surface mounted parts.

Most to all GM ECM have 2 part sockets.

Part is solder on the Board is only part of this.
Carrier holding PROM and MEMCAL in units w/ them are the other Part and "Keyed" to stop plugging in wrong.

But when the PROM etc is Out Of the Carrier... You Can put that in Backward and destroy the chip first time you power up the board.

You can't plug in chip w/o the carrier because carrier makes pressure to the chip and socket pins. If you try, this can destroy the chip too.
armos JUN 21, 07:21 PM

quote
Originally posted by sanderson231:
But the EPROM is soldered into the carrier.


No, the chip is not soldered into the carrier. You might be thinking of a 7730 or other later ECMs, which have those large blue modules with the chip soldered on. Maybe the late 4cyl ECMs use those? I've never seen that ECM.

On the 84 Fiero ECM (don't know the pn), and on the 1227170 V6 ECM, the carrier is just a plastic piece that the chip clips inside of.
I use the carrier from an 84 on my car because it's easier to slide the chip in and out of it. It's entirely plastic, definitely not soldered.

Elevatormechanic: if you do end up with a replacement for the whole chip+carrier - save the old carrier as an extra. I don't know of a source for those carriers except salvage.


quote
Ogre:
Carrier holding PROM and MEMCAL in units w/ them are the other Part and "Keyed" to stop plugging in wrong.


I just tried flipping my chip/carrier around and you're right - the carrier and socket are keyed. I never noticed that before. The plastic "teeth" on either side of the carrier are shaped differently.
Mickey_Moose JUN 23, 02:45 PM

quote
Originally posted by sanderson231:


But the EPROM is soldered into the carrier. If you are trying to solve the problem by changing the EPROM one option is to find a used EPROM in the carrier. That's plug and play. That said it is probably easier to find a complete used ECM w/PROM.




Sorry, no - the carriers on all stock Fiero ECM are plastic - the carrier can be removed simply from the ECM and the EPROM can then be removed from the plastic carrier (but it takes some work as the pins are tight up against the plastic). Not all of the PROMs are EPROMs (one time burn only) - I have seen both. The IC has to be removed from the carrier to erase/program it.

They are 2732 or 2532 EPROMs - the IC are considered obsolete, however you can still find new ones (lots of "refurbished" ones).

The carrier only fits in one way as they are keyed (although I am sure you can get it to fit if you try hard enough) - BUT it is important to note the direction if you remove the IC from the carrier as it can fit either way back into the carrier.

There are 3 different files for the 84:
2.5l with auto
2.5l with manual and 3.18 gears
2.5l with manual and 4.10 gears

Yes, the auto EPROM will work in a manual car, but there are differences in the fuel maps/etc between them all and you should get the correct one for best results.

[This message has been edited by Mickey_Moose (edited 06-23-2023).]