Found an old post of yours that says you are using the 16149396 ecm. If that is tru then according to my doc A2 goes to one of the IAC pins (C102 pin J on the 3.4's engine sub harness, that's the black 10 way connector). B2 is not connected to anything.
On your fiero wiring diagram, bottom right by the fuel pump it says 3-way connector. I believe that C502 (well it is on mine but mine was an 85 4 cyl so your milage my vary), anyway assuming the numbers are the same I 'think' that's down on the lower firewall somewhere (my book says center of rear firewall).
For C502:
A goes to earth. Its the earth for both the pump and the fuel gauge.
B comes from the fuel gauge, other side of gauge in i/p goes to batt +ve.
C is the fule pump +ve supply it connect to C203 (clear connectors under center console) pin L (car side)
The engine side of C203 Pin L goes to:
ECM Pin A20
Fuel pump relay pin B
Oil pressure switch pin C
Hope that helps some.
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Dave E
www.ltlfrari.com