Well said. In every rabbit hole journey, I always try to look at the positives of what I learn, and especially with this car, every journey brings me more familiarity with the vehicle. For instance in this case, I've learned how the ECU feeds out to all the other modules and can trigger a motley assortment of errors when failing on that one circuit. I also learned that residual charge in the ECU can give these strange 1.5v readings (they've puzzled me along the way, with my rotary switch diagnosis.)

On the other hand, I try to respect other's time and avoid ***** like this but you're right, this forum is invaluable.

 

The ECU takes an earth connection as a signal. Sounds like you have connected a +12v where it expected 0v and in consequence have burnt out the sensing transistor in the ECU though this may not be a discrete unit but inside a multi pin chip so not individually replaceable. as you put it on your bumpers "**** HAPPENS"

 

1997 is AJ26, that ECU does not use signal to ground. That didn't change until AJ27.
As OP noted, problem is resolved.

 

does in my 97 diagram

 

You are misreading the diagram.



The only connection to the ECU from the rotary switch is PN - you can see that comes from the fuse box 43E (which is 12v and is the WR wire the OP grounded) and goes to the ECU 04.1 04.3 PARK NEUTRAL. So when the switch is closed the ECU sees 12v and when the switch is open that input is floating (pulled down internally to ground).

All he did was blow a fuse if you read the thread.