Sorry Carl i'm not sure i follow you. You recommend a bulb from the ECU pin4 (control wire) to positive? Please dont be insulted as im sure its me being naive, but what would this show? As I see it the ECU provides a power feed down this wire, would the 2 feeds cancel each other out and extinguish the bulb? The feed from this pin is only 3.3v backprobed at the ECU plug and the Relay.

sorry if im being thick!
Craig