TraviZ

iTrader: (2)

Since I finished this '727 conversion from '165, I cannot run a scanner, Check codes, And my SES light is always on. on the new 727 ecm, Pin B3 is labeled 'diagnostic test terminal' which I replaced with pin A9 from my 165 ecm which was labeled the same thing.
Pin B5 and B11 on the '727 ecm Both were labeled as 'serial data'. But only pin A8 is labeled as 'serial data' and according to the conversion table I used, I placed A8 from my '165 into Pin B11. And left B5 empty (I later tried placing A8 into B5, But made no difference, I put A8 back into B11.) I have not tried bridging the Pins B5 and B11 together.
Lastly, Pin B1 on the '727 ecm is labeled for the SES light, Which I placed with Pin A5 from my '165 ecm.
Here is the Wiring Diagram for both ecm's if anyone would like to double check for me. Pretty much the only thing I have not tried was bridging pins B5 & B11 together.

Please help me guru's. This is annoying me. Car drives fine, But I can't properly tune with this issue.

'165 ecm ftp://ftp.diy-efi.org/pub/gmecm/manu...9-165v8MAF.jpg
'727 ecm ftp://ftp.diy-efi.org/pub/gmecm/manu...727V8TPI-7.jpg
or ftp://ftp.diy-efi.org/pub/gmecm/manu...727V8TPI-8.jpg

RBob

iTrader: (1)

You mention a solid SES light, if it doesn't do the blink off at key-on then the ECM is running in backup mode. In this mode there won't be any ALDL serial comm.

RBob.

TraviZ

iTrader: (2)

How come it would run in backup mode? Even with the stock prom in it and not the moates adapter? What would cause this situation?

TraviZ

iTrader: (2)

Also I want to add, When I burn proms and install them, I do notice the difference I make, So the ecm is reading from the proms, Don't know if that makes any difference. Whatever this backup mode is.

TraviZ

iTrader: (2)

Ok I have to come clean and admit, Maybe I felt a difference, But it was all in my head, I borrowed a new ecm from work today and Plugged it in, I was able to read code 12 right away, I didn't fire up the car or drive it, But maybe I can safely assume now its the ecm that is bad? I will probably purchase the new one tomorrow.

RBob

iTrader: (1)

Yes, it does sound like the original ECM is bad. Don't forget to check for the SES blink. I always check for it every time I key-on after a new PROM burn.

RBob.

R290

Thanks this help a bunch. I feel much better seeing data again