Ms3x no 5vref I think
 

Hi everyone, new to pretty much everything here, but I need help. I got an ms3x built buy diyautotune and built an adapter harness to the stock ecu connectors on my 99 1.8 miaduh. I dont have the test rig to check all connections, so I have my ecu in my car. The ecu just isnt powering on, and I dont know why. I have checked all of my connections, they are all solid connections with no resistance or anything. I built my harness per a pinout I found on here, that i'll attach. Really lost here, any help would be great. Also I am going to be running an aem eugo on my otherwise bone stock miat if that changes anything.
https://cimg3.ibsrv.net/gimg/www.mia...a0268b02d4.jpg

Is it a V3.0 or V3.57? Have you check for 12V with multimeter on Main 28 and Main 8/9? How do you know it's not powering on, just that it's not connecting to your laptop?

Read through the corresponding MS3 manual (for V3.0: http://www.msextra.com/doc/pdf/MS3XV30_Hardware-1.3.pdf) there's a testing section 13.5. If you are getting 12V at the MS3 connector, you have the proper USB chipset drivers installed and still can't get anything out of it, you can pull the MS3 daughtercard and run the tests there. If the MS3 is getting the proper 12 and 5V voltages on the daughtercard connector but it's still not doing anything, then it seems like a daughtercard issue.

Also use trubokitty.com as reference. Much more comprehensive with writeup instead of just using a pinout.

Its a v3.57. My miata is my daily and I have work so i cant check anything right now unfortunately. Will update when i can. Also the ecu is not connecting to my laptop which makes me think it is not powering on.

I would definitely start with checking 12V on the MS3 connector, then make sure you have the right drivers installed for your cable. That's the biggest mistake I see people make, they think it's hardware when it really was just a driver mismatch or a bad cable.

Have you connected the ECU to the OEM connectors without your patch cable?

UPDATE
 

I am just dumb guys, my wiring was a bit messed up, just redid everything and all is well. Thank you guys for all replying so quick.