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Does anyone know what this is for?

Posted: Sun Mar 22, 2026 7:31 pm
by MarkTunny
Any ideas what the little knob is for on the right of the steering wheel? It seems to make some noises at the control box under the bonnet nearside wing, but nothing happens when i flick it left or right.

Cheers in advance

Re: Does anyone know what this is for?

Posted: Sun Mar 22, 2026 8:55 pm
by simmitc
It is non-standard add-on, so you need to trace the wiring. There is no control box on the nearside (left hand) wing. Is your car from the period where an indicator/brake light relay system was used? If yes, then there would be a relay box on the right inner wing. Can you post a photo of the phantom control box, and, as mentioned, trace the wiring for your mystery switch.

Re: Does anyone know what this is for?

Posted: Mon Mar 23, 2026 9:50 am
by geoberni
As simmitc says, it's not standard, in fact none of that is.
On 1000 cars, it was a blank structural panel, on MM/SII it was used to mount the Trafficator Switch and that looks like the Trafficator Switch hole has been repurposed. :-?
Is it a Split Screen MM/SII?
The 2 Buttons/lamps (white and orange) on the right are also of unknown origin, so perhaps related to your mystery control.
If that lever switches to the Left and Right, I can honestly say I've never seen anything like it.
The symbol on the top looks like a fan. Very peculiar. :-?

We all eagerly await some photos of the Mystery Box....
This is the great thing about these Forum pages; on Farcebook one or more keyboard comedian(s) would have already been responding with childish suggestions. :wink:

Re: Does anyone know what this is for?

Posted: Mon Mar 23, 2026 6:02 pm
by Bill_qaz
As a pure guess, indicator or trafficator switch orange warning light and white horn button. More info required :-?

Re: Does anyone know what this is for?

Posted: Mon Mar 23, 2026 6:43 pm
by myoldjalopy
Ejector seat switch?

Re: Does anyone know what this is for?

Posted: Tue Mar 24, 2026 10:26 am
by Mervin
"Ejector seat switch?"
Or it could be a redundant switch for the previously removed flux capacitor? Left = high capacitance, right = low capacitance, centre = bye passed. 8)

Re: Does anyone know what this is for?

Posted: Tue Mar 24, 2026 10:35 am
by les
Ask Scotty, he would know.

Re: Does anyone know what this is for?

Posted: Tue Mar 24, 2026 7:05 pm
by geoberni
geoberni wrote: Mon Mar 23, 2026 9:50 am
We all eagerly await some photos of the Mystery Box....
This is the great thing about these Forum pages; on Farcebook one or more keyboard comedian(s) would have already been responding with childish suggestions. :wink:
I spoke (wrote) too soon..... 8)

Re: Does anyone know what this is for?

Posted: Tue Mar 24, 2026 9:00 pm
by MarkTunny
Ok, update after a session in the garage tonight.

"Control box" as I called it is picture mm1 below. Its period but I suspect its aftermarket. I checked for live feed - nothing without ignition on. Once ignition on, I tested all four incoming connectors (some of these appear to go to the headlights but I havent yet fully traced all the connections, just checked inputs). On the topmost connection, with ignition on - nothing, but if I move the "lever" to the left, I get around 2v, and if I move it to the right, I get 12v and a clicking noise from the box (its intermittent though).

Interestingly, I spotted the same, or similar, hole in the dashboard on the passenger side too - and it really does look quite factory. So I assume that whatever it is must've been factory and prepp'd for LHD and RDH as a shell. No further forward with fully tracing it all, but thought I'd share what I've found so far.

Cheers

Mark

Re: Does anyone know what this is for?

Posted: Tue Mar 24, 2026 9:40 pm
by philthehill
That looks to be a flashing indicator control box for models with separate flashing equipment.
The holes in the strengthening panel are factory fitted as it was where the trafficator switch was fitted for both R/H & L/H drive cars.

Re: Does anyone know what this is for?

Posted: Tue Mar 24, 2026 9:50 pm
by chrischris59
That's a flasher relay and why it clicks on one circuit when you move your mystery switch. :D

Re: Does anyone know what this is for?

Posted: Tue Mar 24, 2026 11:51 pm
by Bill_qaz
See bottom of this post for diagram of DB10 courtesy of Berni
viewtopic.php?p=717479&hilit=DB10#p717479

Re: Does anyone know what this is for?

Posted: Wed Mar 25, 2026 11:49 am
by geoberni
OK.... So what you seem to have there is some past owners DIY replacement for an Indicator Switch.... :-?
There are aspects of this installation which are confusing me, which makes me wonder if it is a Saloon to Convertible conversion.
Possibly even converted from LHD to RHD...
Image mm4. The DB10 Relay is marked as 8/61, so August 1961 production from Lucas. I therefore imaging the car is later in1961.

However....
Image mm1. This show the DB10 on the LH/Passenger inner wing, but it should be on the Drivers side...????
Perhaps it used to be a LHD????
Look under the front floor carpets, is the brake Master Cylinder under the LH or RH front carpet??

The Reinforcing Plates have holes in for the old Lucas Trafficator Switch, used up until the end of SII.
This plate does not have the hole when fitted to post 1956, S3 and S5 cars, because they had the Steering Column Stalk :-?
As seen in this image of a 1960 car found online:
1960 layout.JPG
1960 layout.JPG (51.35 KiB) Viewed 6762 times
I assume your car hasn't got an Indicator Stalk. :-?

Please tell us what you know about the car, including is it a split screen or not, what is the prefix on the Vehicle ID Plate near the Voltage Regulator.
We don't need the actual numbers at the end of it. It'll be something like MA*/*/*...
A photo of the engine bay like this, would be helpful.
The Red Ring is where the DB10 should be, along with the actual Flasher Unit. The DB10 is not the Flasher Unit, it only controls what lamps are flashing.
DB10 Engine Bay.JPG
DB10 Engine Bay.JPG (100.26 KiB) Viewed 6762 times
This car appears to have some very unique aspects, far greater than a mere unidentified switch you initially asked about.

Here's a clear version of what the connections are on the DB10.
This illustrates the Brake Pedal pressed, with Right Indicator Flashing.
if the Indicators are off, the un-powered Relay routes the Brake Light supply on 5 through to 3 & 7.
DB10 Colour v3A.jpg
DB10 Colour v3A.jpg (672.36 KiB) Viewed 6749 times