I thought I'd share how relatively simple it is to add an additional wire to a DIYAutoTune relay board cable. For me the hardest part was finding the female D SUB crimping pin connectors. After some research online I was able to source 100 of them for a few dollars. Here are a few photos of how I was able to do this. BTW the reason why I'm doing this is I'm going to be using GM's ESC module and wanted to wire this to the relay board instead of the MSII board itself. The DIYAutoTune relay cable does not have a wire on pin 5 which I needed. So hence the addition of the wire.
These are the supplies
Hood off to expose wires
running the wire through the harness
crimped crimping female d sub pin
inserted and almost finished
all done! just repeat for the other end and you are all set
After you are all done I recommend to test it with a multi meter. After that you are done!
