Two way momentary contact switch under S4 dash

[JonB]

Whilst dismantling my S4 dash, I found a couple of switches next to the steering column. One is a slide switch which looks to be for hazard lights. The other is a momentary contact switch with three positions. When released it occupies the central position; then you can push it fore or aft. It is definitely original equipment. The workshop manual suggests it might be a brake fail test switch, but the car has no warning lights for this.

The connecting wires are blue, blue/red and blue/white and they are soldered directly onto the switch (same as the hazard switch wires).

Any ideas?

Edit: found RB on the schematic, it’s the brake fail light circuit.

[HCA]

Headlamp related. But I cannot see why. Brake fail test should not use any colour with Blue in it. (But yes, it is Lotus)

How exactly are the wires connected to switch? Is it B to centre pin with B/R and B/W each to an outer pin?

[JonB]

Blue to centre, blue/white to pin nearest dash, blue/red to pin furthest from dash.

[HCA]

Weird.

This is how a dip switch is wired. But a dip switch is not a momentary type!

My only thought is it is a dip switch that might have lost its latching capability - unlikey that both positions would lose it, but I can think of no reason to have a switch as you describe.

[smo17003]

Was the normal column mounted main/dip switch in place and functioning?

Mike

[JonB]

Yes, I have a column mounted dip switch, connected to the normal wires.

[JonB]

Update. I pulled the switch completely off the loom and it looks like an aftermarket thing for an electric aerial. It’s not actually connected to the loom. But I did also find a pair of bulb holders wrapped up in tape with red/black and green/purple wires powering them respectively. They do not appear to be on the S4 wiring diagram, though they’re in the right place to be handbrake and brake fail warning lamps. Even though there are no holes in the dash for them…

[HCA]

Yes, the switch is certainly suitable for an electric aerial, however whoever fitted it is a bit naughty using Blue coloured wires. These colours are strictly for headlights in older cars (modern convention does use a blue in stereo systems). If you continue with this installation, then aerial should be Purple/Grey and Purple/Orange with Green on the centre pin...

[JonB]

I worked out that the lamps are as I suspected, brake fail, handbrake warning and hazard indicators. I found the hazard flasher unit wires wrapped up in non factory insulation tape and the colours don’t match the wiring diagram in the manual. I suspect there is an error there, which lead to my confusion.

As to the aerial switch, I probably won’t use it. I’m not sure I’ll be able to hear the radio anyway. The car has a manual aerial at the moment, which is broken. I don’t know if the radio even works at the moment.. but it’s MW only and I don’t think there are many U.K. broadcasters using that band.