Does an ECU schematic exist for an 84-85 N/A? I've found the pinouts and everything in the manual, but I figure it would be easiest to diagnose any possible ECU problems with a proper schematic.

 

if you find one please tell the rest of us. I spent a lot of time looking for a schematic but no dice.

 

Are you talking about the actual internals of the ECU? That was never documented by Nissan since the protocol is to replace a damaged ECU, not repair it. Having said that, you can easily remove the ECU cover and inspect. The most likely issue would be a burnt resistor ( see: https://www.zdriver.com/forums/280zx...l-issue-41021/ ).

BUT, a toasted ECU is usually not the problem, rather a sensor or wire. Do the proper checks via the FSM.

 

YOU CANNOT DIAGNOSE A ECU OR PCM ... PERIOD
the closest thing to it is self diag. per the FI section of the FSM
for pre OBD like 75 to 89 nissans, a break out box is used to test ohms volts on circuits.
basicly testing inputs not testing the computing of the IC
the conditions for integrated circuits are beyond what a man can test

really it gets into logic probes and looking for high signal , low signal or high -low signal
the signals throw it for 5 /1000 of a second ( back in 98 could be a fraction of that now ) which a logic probe displays

and the 5/1000 timing of that 5/1000 signal ,so if you saw a logic probe high signal how do you know it is sent on the right fraction of a second ?
some imputs throw the signal 5-10 times a second if it's out of that range it shuts down other outputs ...it gets way to complicated.. way to quick

when the PCM's came into service, some not IC literate big wig @ mitsu demanded that the vender send trouble shooting manuals for the PCM it's self
they sent 20 -30, 400 p. books detailing the signals requirements to the IC to function and a note saying here is the info you requested and it is exclusive to one model and year will work on getting the rest rounded up