Hi all,

What's the difference between these two pins? From what I saw on an 1989 Trans Am wiring diagram, these appear to be are exactly the same. Can anyone confirm or deny this? If they're the same, why have them both in the first place?

 

They are both information terminals from the ECM and pin "M" is actually a wire spliced to pin "E". The difference is the baud rate of the signal.

 

If one wire is spliced into the other, how can the baud rate be different?

 

E and M on the ALDL connector are both coming from A8 at the ECM. It's the same signal from the ECM.

 

The two different baud rate signals that I mentioned are 160 (pin "E") & 8192 (pin "M") are used in scan tools and if you will go to the link below you will get a better understanding of what I meant.

https://www.thirdgen.org/techbb2/sho...hreadid=275242

This link is under the DFI & ECM forum and more can be found about it by searching that forum.

 

Ah, well if it's the same signal on both E and M then I'll do my wiring with the splice from M to E.

Thanks for clearing that up for me!