Should I just replace the whole ECM or can I replace the chip? I have a code 51 showing my PROM is bad.

It is rare that the prom chip goes bad but it can happen. To replace the prom chip or ECM remove the shift knob, then the shift console,cigarette lighter panel and glove box console. That exposed the ECM. There is a door on the ECM held by two hex screws. Remove that door and the prom chip is the Block Plastic Plug in carrier that is on the right. If you need a chip, email me off list and I'll see what I have.

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87GT 3.4 Turbo Best 0-60 5.2 seconds
http://turbofiero.fierojoe.com/turbo.htm

Just a side note to the above....look at the PROM before you remove it. There is a semicircle notch cut into the top of it. Make sure you put the new one in the same direction or you'll fry the new one. Also, push the prom in all at once with two fingers until it seats. If you're not sure, pull it back out and examine the lil prongs. They must all be straight. If you bend one, just bend it back straight and try again. Hope this helps!

Phil

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GTDude
OVER 25 years GM experience

thanks for the quick replies guys!

Make sure you disconnect the battery first. If you don't, you can spike the chip and ruin it. Make sure you ground yourself before touching the chip or the ECM or the same can happen. Good luck. Static electricity and electronics don't mix.