I just unplugged the boomslang harness from the stock ECU while the key was in the ON position. Now none of the LED lights are lighting up and the fuel pump isn't running for the priming pulse. I'm about to try connecting with a laptop, but are there any definite failures that will be cause by unplugging the stock ECU?

All fuses checked OK.
MS1 parallel on a 92.

 

More information:

I checked power on the board according to this thread, http://www.msextra.com/forums/viewtopic.php?f=4&t=37973
and here are the results.
I couldn't find S12 and S12C. All 12 volt points check out OK.
For 5 volts, S5, the proto area, D19, and CPU pins 1, 20, 31 all measure only .19 volts.

 

Can you measure 12V on the left leg of of U5 and 5V on the right leg of U5?

 

Yep. I have 12v on the left and 5v on the right.
I noticed that d19 shows continuity both ways.

 

I removed one end of D19. All voltages give the same reading. I noticed that C18 is very hot to the touch.

I guess I won't be going to the autocross tomorrow. Sarah is sad. :(

 

Let this thread be an example of what will happen if you attempt to use the left side of D24 to pass a jumper to the other side of the board. I was trying to get JS11 connected to SPR3. It was working at first, but I didn't notice it stopped working until I unplugged the stock ECU so I assumed it was the unplugging act that caused a failure. I undid the jumper, and everything appears to be working fine now. Awesome!

That said; if in doubt, use the proto area.