Ignition Signal Absence Due to Direct Battery Bypass

Connecting the main battery positive and negative wires directly to the controller provides high-current power to the motor drive stage, but it does not automatically energize the controller's logic circuit. Most SW900-compatible controllers require a separate, low-current 'ignition' or 'lock' signal wire to be energized by the positive battery voltage to initiate the system's 'wake-up' sequence. By bypassing the ignition switch without ensuring this specific signal wire is also connected to the positive source, the controller remains in a dormant state. Consequently, the controller fails to activate the display or establish communication, resulting in a blank screen despite the presence of main battery voltage at the controller's primary power inputs.

Sources