MIL light on

[Plan B]

After having changed the dashboard and replaced the dash panel LEDs with new replacements last week I'm now getting the MIL warning light on when running. Rover Gauge is showing no fault codes (and I've cleared them down as a second precaution) and the engine sounds sweet. How can this be happening? Is there a specific way to extinguish the MIL other than clearing all fult codes?
One question: - does the 14CUX supply a permanent live feed into the warning panel and switch in the earth return when in error condition? (I only ask this because it might give me a clue to look for a spurious earth in the LED circuit
Another question: - anyone know the wire colours feeding the MIL warning light (I ask this because I might have connected the wrong wires to the MIL)