https://docs.emtronaustralia.com.au/engine-management/wiring/shadow-8/shadow-power-distribution-wiring/index.htmlShadow Power Supply System The Shadow 8 power supply system has been designed to allow flexibility on how the ECU manages power-up and power-down sequencing. The real advantage is on the power-down sequence, allowing the ECU to power-down once all pending tasks have been completed. This effectively acts as an internal Hold Power System. ECU Supply (Pin A1) Pin A1 is the main power supply into the ECU .Hugoen-us