Bad ECU 1.6 8v 1990.

[fixkick]

i See damage there.
on the last photo.
is see clear evidence, of damage, and attempted repairs. near R102. (my guess, is this damage was from hot wiring sensors on car, by wild men,(common)
then blew up those parts there, and then attempted repairs, and was not effective or only partially, gaining only backup mode. only.... (my best guess not in MY HANDS)
is that B15 pin damage B is green in this car. (b17,b16,b15 ( B17 is behind B1) if yes, someone blew up the ISC driver, line)
B1 and B7 is 12vdc power.
B2 /B3 is ground. (for power)

I think this ecu is bad.
a bench test is easy if done with care , power and ground and a less that 0.100amp 14v lamp , on CEL. spec for lamp is 0.050amps 50 mA, due to transistor cant do more . than that.
the dash lamp cel lamp, is the lowest ampere lamp in car, not by accident.

if it (CEL) dont flash on demand, it is a bad ecu. 89-95 usa and many more years, in ROTW (rest of the world) on all cars until, around EUROPE EOBD kicked in, (simular to usa OBD2)
some cars sold by suzuki run this old stuff OBD1 (suz) until 2004.
its cheap and keeps car costs lower..