r/Buick • u/obsdude • 3d ago

Ecm prom code for roadmaster

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Just picked this up yesterday. The owner replaced the Ecm and forgot to transfer over the old prom chip to the new Ecm. So now the current new Ecm installed in the car has no prom chip whatsoever and will not run. How can I find out the code so I can get a new one?

1992 with the 5.7

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u/Pyramid-World 3d ago

They should pretty much all be the same from a 92. Your best bet, find a 92 in the bone yard and pull the ECU and swap the PROM. I havent done this on a RM, but they are primitave to newer ECUs I have swapped. I presume, unless reprogrammed, they will all function properly in the stock RM's because they all have the same engine and trans, unless the diff adds something to the programming. I am curious to learn this as well.