I PICKED UP A 1986 GL 10 WAGON WITH A BAD ENGINE,FOUND  ANOTHER ENGINE,ALL HOOK UP,ECU IS GIVING CODE 12,TROUBLE SHOOT,THERE IS POWER TO ECM,WHEN CRANKED.ALSO INJECTORS NOT GETTING POWER,TRIED ANOTHER ECM SAME THING.DO I HAVE 2 BAD ECMS OR IS THERE SOMETHIG CAUESING THE ECM TO FAIL.ECS LIGHT IS ON.I DON'T WANT TO TRY OTHER ECM.AND HAVE THE SAME PROBLEM,ANYBODY RUN INTO THIS PROBLEM,THANKS ED

All I know is in 1985 the MPFI had a ground wire on the manifold. The injectors won't fire unless this wire was grounded. Recall it used one of the intake manifold bolts on the passenger side. 

The ECMs do not power the injectors..

Check your fusible links.

There are 6 locations for common electrical problems can occur on the 86 GL10, where I had problems.

1.  The black fusible link broke from getting hot and brittle

2.  The hot wire coming off the alternator breaks from getting hot and brittle

3.  The engine ground wire at the body connection end, gets hot and brittle while engine is running, and loses it's conductivity

4.  The black wire that runs between battery + connector and the bottom of the fusible link box, gets brittle at the battery end.

5.  The capacitor between the coil, the ground, goes out.

6.  The starter wire at the battery + connector, breaks.