MS3X Grounding Issue - did i fry the whole thing?

[abeebe718]

Background:
BMW e34 540, turbo m60 v8
MS3X w/quad spark modules for sequential ignition
DIY BOB, reusing the oem harness
First foray into Meagasquirt, first post.

So I'm hoping I have completely over thought this and just have something backwards and it will be a simple fix, but at this point I've confused myself and need some guidance. The short question is, where do I ground everything? The expanded version of that is as follows.

I started by grounding all of the grounds from the main and ms3x harness together, turned the key and went to calibrate the TPS (this is as far as I've gotten in this process), but had no difference in open and closed throttle voltage. It was seeing full voltage at both readings. I quickly realized this was because the sensor wasn't actually grounded. Now since I'm using the break out box, my logic was that I should pin the grounds from the MS harness to the corresponding ground pins on the stock harness. I used 2 manuals to make sure I had the correct Bosch DME pinout. See one here... http://www.armchair.mb.ca/~dave/BMW/e34/e34_95.pdf Starting at page 101.

So I took grounds from the ms and expansion harness and soldered into the correct (or so I thought) pins on the adapter board. Example, spark and fuel ground are listed on the OEM pinout, so I used grounds from the ms3x harness for these pins. Other sensors, like tps etc., i used grounds from the main ms harness. The remaining grounds from both harnesses I grounded in the engine bay.

Thinking this solved my problem, I opened tunerstudio, turned the key...nothing. MS didn't power up. I grabbed my multimeter but noticed that on of the ribbons on the BOB board had gotten hot and peeled up. (see pic in next post). Immediately shut if off. Using a contstant 12v source, i checked that all of the pins I had just soldered were in fact grounding and got no contrary results.

All of that to ask 1) what are the odds I toasted the cpu? and 2) What is best practice for grounding when using the diybob? SHould I ground the ms/ms3x harnesses and pull out the grounds from the OEM harness and ground it all to the same point on the block/head? Was my logic sound and I just have a short or something crossed? Any help is much appreaciated.

[abeebe718]

Update - I tried connecting to the stimulator and my computer still wouldn't recognize it. Disassembled and began voltage/resistance testing. Narrowed it down to the U5 voltage regulator. It got painfully hot to the touch within a few seconds and had the same voltage (just under 9v from the stim) going in and out. Going to replace it and see what happens.

[Matt Cramer]

Also check to be sure D19 isn't blown.

[abeebe718]

Also check to be sure D19 isn't blown.

Thanks for the tip. Turned out D19 was the culprit.