51 chevy

hello im using a willem programmer I can copy my stock aujp chip and erase burn and verify my 29c256 chip but when I put it in my car the aldl will not go into diagnostic mode aldl will not blink and the computer will not connect to gmecm diagnostic .I also have a hyper chip that does the same thing but the aujp chip works.one question is the amel29c256 a replacement for the 27c256?is there anything in the programming that has to be changed like on maf eprom?the hyper chip is a 27c256
thank you

:lala:

Grumpy

It should be a drop in.
Try *cleaning* it, by programming it with a .bin file of all FF's. Then try again.

The 29xxxx series seem to need that from time to time.

Also, when you turn the key off give the ecm a couple secs before pulling the prom off. It resets the IAC and might be reading it, if you pull it out too quick, that could pop it.