Breezy_Pete

Red/blue and blue/purple are the wires going to the motor in the passenger front door lock. Slightly thicker than the other wires going to the lock (except the brown one). They will be polarised oppositely depending on whether the door is in the process of being unlocked or locked at the time of measurement. You will probably need an assistant to be pressing buttons while you try to measure voltage between these two. If one wire never shows a voltage it may be broken at the door hinge. Feed volts directly in at the points you can access, until the door unlocks. If you do see reversing voltages in the wiring, then the problem is the lock module itself. The accessible section of the lock wiring is shown in the green rectangle here (passenger side on a UK/RHD car):

Yes, I believe it is possible to reach the 3 Torx head screws at the bottom of the card, but not easy with seat in the way. Then door handle unscrewed, window switch wiring disconnected etc. then pop out the 3 clips at rear and front edges from bottom upwards. Front edge will be difficult where dashboard overlaps doorcard, I think. Will check wire colours to lock motor now. Maybe there's another screw up near the door opening handle on inside, can't remember?

Passenger front door lock or wiring/connections to it. Everyone reading should note that the time to address such issues is when they are intermittent, before the door cannot be unlocked. If you can wrestle the door card off, despite the door being shut, I can tell you which wires (which will now be accessible on inner side of door) drive the lock motor. You could then pierce insulation and measure voltages to see if power is getting that far.

OK, so there is a bad connection in the driver's door wiring, but with remote-activated unlocking, I believe that would not affect the passenger door lock. With RF remote central locking, the individual lock motors are driven by relays in a central control unit, which is also the receiver for the remote radio signalling. If you only had key in lock central locking, a fault on driver's side could affect others, as the lock/unlock command signals (key position really) come from that door lock module, rather than central convenience unit

So when you try to unlock with remote keyfob button, all doors except passenger front door unlock?

That relay looks like one that would be mounted in the engine bay. Can you offer reg number or VIN so I can check where yours should be. What's below the light switch? Looks like a panel or something between light switch and diagnostic socket?

What year is the car, and does it have RF remote central locking, or just key in lock C/L? I think it's quite unlikely to be the damaged wiring in driver's side, unless you can see broken wires inside the damaged insulation. Usually the wires last a long time even when the insulation is cracked, in dry locations.

Please confirm that when you are measuring voltages with your meter, you are connecting the negative probe to something that is unpainted metal, connected to the car body? The outer connection/tube of the cigarette lighter socket would be an example of this.

Fuel supply relay has permanent 12V to connections 30 and 86, as seen in the diagram, red wires. Ignore that one for now though. Focus on fuel pump relay connection 85. Positive meter probe in that, negative meter probe on chassis earth, with ignition switched on so that the instrument cluster lights up various warning lights.

Fuel pump relay is in position 14, fuel supply relay (triggered by door opening only) is in pos 10.1

Because the fuel pump relay is not being energised. If you look at the back of the cabin fusebox, you may be able to see solid metal 'busbar' connections linking two groups of fuses. One busbar will connect all the fuses that are permanently 12V. A second busbar probably connects all fuses that should be switched on by ignition switch. The others are not so easy to describe, where there are wires going to both sides.

Can you post a close-up picture of the relay sockets, especially position 14? Need to check that you are measuring correct point.

The second thick black wire, to the right of the missing fuse, is bolted to fuse SA2. It is supplying 12V to interior of car including that connection of ignition switch. Is that rust or red dust all over that fusebox? You must have continuity through that fuse or nothing in the cabin would be working, now I think about it. Just to check, when you are turning the key to switch on ignition, you are seeing lots of stuff illuminate in the instrument cluster, right?

Much more likely to be the light switch, I think.

No, I mean check that there is 12V on both ends of the fuse, to prove it is not broken. I do not know the steps to access ignition switch. Locking problems are unlikely to be related to this.

May be quite easy, but can't remember the technique just now. Involves pushing it inward (opposite of turning on fogs) and turning one way or the other. Then pulling.

There are 3 coils, one plugged onto the top of each spark plug.

Post a photo of the fusebox on top of your battery, and I will highlight SA2 for you, but I expect it is labelled. Ignition switch is under the steering column, operated by the key.

Look again at Jocko's diagram. If connection 85 of the fuel pump relay position (14) does not get 12V when ignition is on, that relay can never be turned on/energised. The wiring to it is simple. Strip fuse in engine bay to ignition switch, then ignition switch to relay holder.

Try 'working' the light switch a bit to maybe clean contacts.

Try leaving the car with the indicator stalk up or down, see if the front and rear side lights on side you indicate towards stay on after you close door and lock up (Parking light function). That could prove bulbs and wiring from BCM to them, if both sides work.

Looks like an error to me. In the circuits I'm seeing a feed from a 40 amp fuse in engine bay to light switch, then the sidelight outputs from there to BCM, then from BCM to the side lights. No individual fuse related to just side lights, although that one (23) is shown as being for interior lighting. Baffling to me, unless it's a light switch fault. What happens if you spin the switch dial a few times each way to maybe clean up the contacts a bit?

I edited my previous post to include a question about where you've seen fuse 23 listed as being for side lights. Owners manual? Random internet site?

Listed where? It isn't in the tables of fuse allocations in Skoda official wiring as far as I can see. Check a bulb, unless you are certain that they were all working recently.

I can't see fuse 23 being involved, that appears to be for interior lights. Have a look at fuse 17 instead.