I just noticed the other day the left turn signal bulb in the mirror stays on together with the puddle light. This does not hold true on the right side and it got me wondering....

 

The indicator works fine otherwise...

 

PS: I installed a Superb W8 Cat vision unit last week - would it have anything to do with this? Haven't had time to try unplugging it and see if it still does this.

What year is your car cos I've had no issue with my pre-fl cat light... assuming you've only spliced it into the correct wire on the headlight switch?

The cat light itself is fine. All working as it should. It's a 2007 Elegance.

 

Its the side indicator light in the mirror that is on when it shouldn't.

 

I tapped into the light switch as per all the guides around here into the blue/gray cable.

I can't imagine any obvious link... I'd be taking the wing mirror apart and check the wiring...

I just removed the W8 connection to the switch and it still does this so there's no link between the two.

 

Having had a closer look just now it seems the led is not constantly on, it's twitching a little bit.

 

Before I take the mirror cap off, can you think of how the wiring can go bad in there? 

Took the mirror cap off today and the weird behaiour suddenly stopped.

 

Moved the wiring a bit and it did not twitch at all anymore.... I guess I can call it "fixed" for now.