Ceiling rose pull cord needs to be switched before wall switch works? Ask questions and find answers to many subjects relating to electrics and electrical work

[pklp16]

Hi,
I recently moved into a 1970s era house. In the utility room there is a wall mounted switch as normal for the overhead light. By the backdoor there is a pull cord ceiling switch. The problem is that the cord has to be pulled before the wall mounted switch will work. The pull cord switch will operate the light as well but if in the wrong position then the wall switch will not work.
I've had a look at the wiring. The ceiling switch seems new, very clean so I guess the previous owner may have changed it. The cable from the ceiling has 4 wires;
Green to earth.
Red to L2.
Blue to L1.
Yellow to Common.
My question is; Has it been wired wrongly and what can I do to fix it?
Any ideas would be appreciated.

[Mr White]

What you have is called 2 way switching.
I would guess one of the switches is incorrectly connected.
As you have access to both switches I suggest that your turn the mains off, and open the plate switch and note what colour goes where.
You will probably find 6 wires. Ignore the earths. You should also find a red, blue and yellow wire, and also a red and a black wire.
Make a note of where the red, yellow and blue wires go, then go back to the pull cord switch and move the wires so they are in the same terminals as they are in the plate switch. (The cable with red, yellow and blue is the same cable and in order for 2 way switching to work, both ends must be connected the same.) Once both ends are the same (ignoring the extra red and black, which should stay where it is) If you switch the mains back on, the light should now work as expected.

[pklp16]

Hello,
Many thanks for your advice. I have checked both the wall switch and ceiling switch and the wires are:

Wall switch:
Green - earth
Black - L2
Red - L1
Red - common.

Ceiling switch:
Green - earth
Red - L1
Black - L2
Yellow - common

Is there any thing else I can try?

[Mr White]

As I first said, the colours at both switches must be in the same order. As you have now said the colours are different at each end there must be a junction somewhere, so unless you can find it or have test equipment the only thing you can do is trail and error.

You need to swap two wires at a time at either of the two switches (Not both) until you find the correct combination.

This is on the assumption that it actually did work in the first place.