I used a AT28c256-15pu but I am getting nothing at the ECU, well the only thing I know for sure is I am not getting a pulse to the rail. I was sure it was compatible when I ordered it but now I cant find anywhere that says it is.

I see I misspelled compatible...

 

The data sheets show that pins 1 & 27 are reversed from the normal '256 EPROM. This is A14 (address line) and the ~WE/Vpp. If you can program those EEPROMs should be able to make an adapter to swap those two pins and it should work.

A modified socket would work to help swap the pins.

Always look for the SES/CEL blink at key-on to see if the ECM is running from the PROM.

RBob.

 

So if it comes on solid no blink then its not reading the prom?

 

That is correct, no SES/CEL blink the ECM is in limp mode. That is, it isn't running from the PROM/calibration.

RBob.

 

Rbob thanks for the help I ordered some SSTs and I now have it running.