If you want, tell me your Nissan model/year and the ECU part number and I’ll fetch a specific pinout for that exact Zexel unit.

| Pin | Wire Color | Signal Name | Description | | :--- | :--- | :--- | :--- | | 1 | R (Red) | Battery +12V (Direct) | Main power supply for injector drivers | | 2 | B (Black) | Ground (Engine block) | Heavy ground for output drivers | | 3 | B/R (Black/Red) | Ignition Relay Output | 12V switched after main relay | | 4 | – | Not Used | — | | 5 | Y (Yellow) | Starter Signal (ST) | 12V while cranking | | 6 – 14 | Various | Reserved for ABS/TCS signals on automatic models | Refer to vehicle-specific supplement |

(such as the main engine relay), it often indicates a faulty ground connection (Pin 85) that the ECU is failing to provide. Advanced Resources for Wiring Diagrams