Burnt Up 2 PTUs!!

[MarkerZ32]

So after I tucked the engine harness and relocated the S2 PTU next to/above the ECU, I got a crank, no-start issue. A quick check revealed loss of spark to all of the coils (I am getting fuel pressure and the injectors are spraying). I pulled the PTU because I moved it and I figured it'd be a good place to start. An Ohm test showed no continuity between any combination of pins. So I plugged in a know good assembly and still cranking and no spark. Pulled that PTU and it lost continuity.

I've searched and read one thread where someone burnt up a couple PTUs and found that it was because he had forgotten a harness ground. This seem legit to anyone?

Does anyone know what pins to test for power and ground before I install the new PTU? I have a multimeter but I can't test a square wave signal with it. I do not want to fry a brand new unit!

[rgregoryb]

There are 3 grounds that need to be checked,one behind injector 6 on the plenum, one behind 5 cylinder near the firewal on the plenuml also one near the AC compressor that connects to the frame. Remove these and clean real well and reconnect. There is a good ecu wiring diagram available on the net that is done in color and it is much easier to use than the FSM one. Just Google it.

[MarkerZ32]

NEVERMIND!!! False alarm, folks! I followed the schematics and found loss of power to every primary coil circuit. The brown connector that comes out of the engine bay fuse/relay box wasn't snapped in all the way.

MODs: feel free to remove this shameful thread...

[DCaff300ZX]

Glad you found the problem, but we do keep these threads to help others in the future with a similar problem/issue...