S3 toggle lightswitch

[robertverhey]

Just wondering if anyone has an intimate knowledge of these three position switches. Couple of issues:

The wire colours coming out of mine don't tally with the circuit diagram in manual, (should be a brown/blue, two reds, a brown/purple, and a brown/yellow)

I have a brown/blue, a single red, a blue/black and a solid blue, as per pic below.

After some testing with a multimeter, I've determined that the brown/blue is the + feed, the red is the parking/panel lights and the blue is,I think, headlights (though it goes to a mysterious relay also shown below, and from there the path gets a bit hazy). As for the blue/black, no idea!

Clearly I'm dealing with a non-standard loom here, or am I?

In any case, the switch seems knackered, I can't get it to reliably connect between Lucars at various positions. Ditto the identical heater fan switch. Prince of darkness at work! If anyone can point me to replacement switches that look the same and work reliably that'd be great. Genuine Lucas preferred.

Any advice would be welcomed

[oldelanman]

Hi Robert,
This may be no help at all but your wiring colours seem to correspond with the S1 & 2 wiring diagram in my workshop manual.....

Sorry the scan is not very clear but if you right click it and open in a new window you can then enlarge it and it's just about readable.

The relay you show looks like the headlamp flasher relay.

Also the colours my manual gives for the S3 are different from those you quote......

Brown/blue - supply
Red - side & panel lamps
Blue/Purple - headlamps via dipswitch
Blue/yellow - headlamp flasher relay (live only when switch in OFF or SIDELAMP positions)

[john.p.clegg]

Robert
Gently,with a thin screwdriver open up the pressed part of the switch (over a tray to catch all the bits),sometimes they can be cleaned and re-assembled...

John

[robertverhey]

Thanks, well spotted roger, I have the brooklands manual (which itself copies the circuit diagrams from the factory manual) and yes as you point out, my light switch colours tally exactly with an S1/2.....tempted to think that an earlier loom has been fitted at some stage, but as it has electric window wiring to the dash switches, that's unlikely. I wonder if this is a case of lotus using up old stocks of S1/2 looms by modifying them...Gawd, anything's possible for lotus in the '60s!

Intrigued that you have another version of S3 wiring colours.....what manual is that?

The loom was in reasonable shape, spent a couple of days now replacing burnt sections and regrouping and taping wires. The sections that burnt were from the courtesy light on dash and the cigar lighter.....

Thanks John, I did prise the switches open, can't help myself! What a strange arrangement and what a proper bugger to reassemble, if those springs come adrift, which they did.....very vocabulary-broadening!

Further thoughts most welcome,

Robert

[oldelanman]

Intrigued that you have another version of S3 wiring colours.....what manual is that?

I have the factory workshop manual.... October '72 edition. The S3 diagram is an A3 fold-out page so I can't scan it all. As before it's a poor scan but if you open it it a new window as above hopefully you can decipher it.

[robertverhey]

Oops roger, my bad, got my U (blue) and N (brown) mixed up

Yes we're on same page

Blue yellow and blue purple it is.

But looks like the S1/2 diagram is going to give me more to follow than the S3 diagram

[lotusfan]

Robert

If it helps the MGB and MG Midget light switches from around 1964 - 1966 look the same but are unlikely to have the extra contact for the headlight flasher although with your new found dismantling skill you may be able to get a new one and modify it!! Moss sell the MG switches.