This article may be of interest: http://eu.st.com/stonline/products/f...m/epromfaq.htm With the average age 3rd gen now reaching 20+ years old this can start to be an issue. Even factory service eproms are subject to the same problem.

about a year ago GM released a bulletin regarding harness failure that are 20+ years old. My car was always garaged and cool climate so I may be OK.

However lately I am getting random prom failures with blinky CE light. I loaded a .bin in my prominator yesterday and car ran fine all day and this am cold start I get CE rapid blink. Loaded a diff .bin and all is OK. I can flip to a diff chanel and use another .bin and all is OK. It may be the ribbon from Prominator to lappy. Another posted a failure of ribbon. May be ECU? or harness? Dont know.

I notice that automotive EPROMs have a checksum and there is a "Code 51 - EPROM Calibration Error" on older vehicles if this checksum does not jive with the contents of the EPROM memory. If this happens, the vehicle runs in a default mode and does not use the EPROM data. (Which is nice if you read the following...)

The question is when and how often is this diagnostic check run?

Following is more information which says when an EPROM fails, one bit may flip from a 0 to a 1 or a 1 to a 0 (called "bit flipping")!

Flash Memory Reliability...
http://trs-new.jpl.nasa.gov/dspace/b...262/1/09-9.pdf