MS3Pro Module PNP works one day, not the next. Stock ECU works.
 

In nutshell, I have one of Braineack's fully loaded MS3Pro Module PNP units. We plugged it in yesterday, and the car prettymuch fired right up on the first try.
We turned it off, parked the car overnight, and today it won't start. We can't even connect to the MS with a laptop.
We plugged the factory ECM in, car fired up. Then tried the Megasquirt again, no dice, fuel pump does not prime.

Is there something obvious that could be going on here?

Car is a 1990 with a Greddy turbo kit, aem wideband, ebc, and baro on the board. Help?!

There's 2 fuses on the module you could check.

Will try that and report back, thanks.

In addition, if the battery voltage is too low I think the ms3 just shuts down and prevents a start. I know when my battery was dying it would behave that way.

Nope, that wasn't it. Tried it yesterday with a freshly charged battery.
Still starts fine on the stock ecu.

If the module and the board tested OK by DIY, it might be a bad solder joint in the headers or Tyco connector. Doesn’t hurt to check those.

Was the "st sign" fuse pulled prior to installing he MS?

Don't think Brain uses the active high circuit.

Thanks for all the help guys.

Can’t say, but I don’t believe so.
Unfortunately, this was largely a hands off install for me. I had to pass it off to a shop who had more time and expertise than I.

I ended up one sending the unit to DIY for testing, who was able to power it up and connect it to the laptop fine. It received a clean bill of health, and It’ll be up in the classifieds shortly.

If you can get it to connect to a laptop, try updating the firmware. I had a similar issue with a brain built ms3x and that was my fix