Zexel systems are licensed versions of Bosch designs. In Nissan applications, these ECUs primarily manage fuel timing and quantity via the Electronic Control Lever (ECL) on the fuel pump. Unlike modern Common Rail systems, these involve a complex mix of analog signals and pulse-width modulation (PWM) to move the pump actuator.
Check for 12V at the ECU pins while the engine is cranking. If voltage drops below 9V, the ECU may reboot or fail to fire the injectors. nissan zexel ecu pinout work
Unlike the later "standardized" Nissan ECUs (where pin 20 is always 12V and pin 23 is always ground), Zexel systems are licensed versions of Bosch designs
Working on a Nissan Zexel ECU pinout is not a matter of finding a JPEG on a Russian forum. It is a process of elimination, careful probing, and understanding the of the connector. Check for 12V at the ECU pins while the engine is cranking