Does not work, bulb shows resistance.

NS one is ok.

The door is open light on the dials does not come on when this door is open, unlike the other three.

Clues please.

Micro switch or poor connection?

Edited 18 February, 201511 yr by jackg

Sounds like a door micro switch fault, what happens if the door is open and you press the unlock button on the drivers door window panel?.

Nothing, beyond the clicking of the locking system to ensure it is unlocked.

I would say you have a door switch problem there, does the interior light still operate on that door?.

Yup, interior light works ok on the door.

If you check out the photos in this how to thread, the op details what microswitches do what inside the control unit, so you can see if your symptoms fit in with any one single microswitch failure, but to be honest, most people just fit a new lock unit. http://www.briskoda.net/forums/topic/341937-octavia-door-lock-problem-diagnoserepair-guide/

When my microswitch played up it wasn't always puddle light, interior and buzzer at the same time, it was a bit random. Most likely not to work was puddle light and lights on buzzer. I'm not very savvy with switches and wires so I picked up a used lock mech, solved. Pattern part mechs are pretty cheap too.

I always get nervous when I post that link, as to a lot of people - including myself, that sort of a repair is way beyond our talents. But, what it is useful for is showing which internal switch does whatever function it is designated to, and as such makes fault diagnosis a bit more accurate..

True that. I did seriously consider a replacement switch as per that how to but I just couldn't talk myself into it. Finding a used tidy mech for £15 made my mind up. Time will tell how long it lasts but it's going ok so far. I definitely try not to slam my door which is largely what encourages them to break up? But yeah there is useful info in that link for symptoms, funny how 1 little switch can make you think your car is going nuts.

Sorry my error, the interior light does not work on the drivers door whereas it is fine on the other doors.

So it is the micro switch.

Very much looks like it.

thanks for your comments and links, Iv'e read the howto and ordered a tool to be able to strip it out.

If you have not read this yet, it may be a bit more info for you -  http://www.briskoda.net/forums/topic/126257-octavia-1-replacing-door-latch-microswitch/