I have a TPI motor in a 57 Nomad using a S&P stand alone harness and I think I may have a memcal/prom problem. The SES light comes on and stays on as soon as the key is turned running or not. It only runs in limp mode, will not give codes thru ALDL, and will not comunicate with a scan tool. How can I tell if I have the correct memcal/prom for my application? I am using a 730 ECM and the memcal has the number 34501-1 on the side and the prom has at29c256, 90pc, and 0113 on it. Thanks for the help. Steve

 

the at 29c256 chip is not a gm piece

 

Yes, someone swapped a "flash prom" into your Memcal and burnt "who knows what" on it. The good news is, since you have a flash prom already installed, you can just get the burning equipment and "reprogram" it with a known good bin.

Also, jump the ALDL and see what SES code comes up. For all you know, the person used a V6 Memcal and installed a V8 bin on the eprom. That may be the reason you CANNOT scan the ALDL (as well as a host of other reasons).

But jump the ALDL to see what the SES code is - that may be your first clue. It's obviously not a stock GM Memcal as funstick said.