1G 1g ECU EPROM vs Non-EPROM visual comparison.

Please note my EPROM appears to have been rebuilt at some point and is has extra stickers on it. Disregard the large gold stickers.



EPROM ECU Front Cover

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Non EPROM Front Cover

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EPROM Connector

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Non EPROM Connector

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EPROM Board

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NON EPROM Board

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Side By Side EPROM Left Non EPROM Right

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Non EPROM Side Sticker

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[TuskeeTuner]

From the dead.

Can you describe the difference between a 1G 1990 converted EPROM vs a 91-94 OEM EPROM?

I saved a 1G 92 Laser from a partout which contained a non-EPROM that's been converted, with a 91-94 engine harness, with a wiring configuration setup for a 1990. I hope it's not confusing - further details can be provided later if necessary.

 

[steve]

I'm not sure which difference you're trying to identify EPROM vs non-EPROM, 90 vs 91+ ECU?

The conversion of a non-EPROM to EPROM is the same across all the 1G ECU's. The microprocessor chip is removed and a connector is added to allow a board to be connected that have a new processor and the EPROM socket and support logic. Here's an example of the conversion:

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[TuskeeTuner]

I'm not sure which difference you're trying to identify EPROM vs non-EPROM, 90 vs 91+ ECU?

The conversion of a non-EPROM to EPROM is the same across all the 1G ECU's. The microprocessor chip is removed and a connector is added to allow a board to be connected that have a new processor and the EPROM socket and support logic. Here's an example of the conversion:

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I guess the fact that the ECU was converted is irrelevant.
What visual differences are there between a 90 ECU and a 91-94 ECU? I'm trying to figure out why my 1992 car had the closed throttle idle switch and airflow sensor reset wires were swapped at the ECU, and also why the closed throttle idle switch under the hood was going to a relay which previously controlled the starter.

Thanks again.

 

[steve]

If the ECU is still in it's original case you can check the numbers against http://simon.chi.il.us/ECU/ECUID.html to see what it's from.

Using the ECU's in the first post there are two, a MD165810 and a MD166262. Looking those numbers up show us that the MD165810 is from a Federal MT 91-92 GVR4 and the MD166262 is from a Federal MT 91-92 Turbo AWD (model years typically run from mid the prior calendar year to mid the model year).

If you also look the white edge connectors on each you'll see they have 4 digit numbers that match the last 4 of the second number on the cases. 7378 and 6578, this confirms that the circuit board matches the case they were found in and haven't been swapped. As noted the letter at the end signifies if it's an EPROM ECU or not, but you can see that clearly.

Lastly, both of the examples are 91+ style ECUs since they have two hybrid ceramic circuits running next to the capacitors in the center. the earlier 1990 style have three like these two 90 ECU's. (first is a 90 Federal MT AWD non-EPROM and the second a 90 California MT AWD EPROM)

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[TuskeeTuner]

Thanks for the illustrations and the explanations. I've seen that web site before - but only ran the part number found on the case through the CTRL+F function.

I've determined that the EPROM ECUs I have are both 91+, and that the car was/is mis-wired like a 90 for some reason. Once my contact removal tools show up I will fix that.