[Gmecm] 3.1 Turbo wastegate solenoid

[Rsetina]

I have a problem with a 1990 grand prix ste. The wastegate solenoid 
won't operate. Its grounded by terminal a 18. The tests say it's a bad 
ecm but ive tried  6 different ecms and 2 proms.  What could possibly 
cause this besides a bad Quad driver? Tested solenoid for low resistance 
and current draw tested grounds and power feeds to ecm. all is ok. When 
you jump the aldl terminals all the other solenoids and relays operate.  
What am i missing. Ive owned this car for 12 years first problem i 
couldn't fix. I am a heavy equipment mechanic but used to work for a new 
car dealer and a transmission rebuilder. Thanks for any help  Bob S.