Idle speed solenoid control

[stickandrudderman]

The learned amongst you will know that the idle speed solenoid is controlled by the throttle switch and the system is used across the model range of the period using identical parts. Or is it?
I am old enough and wise enough to know that you've never seen it all, even after 40 years of doing this job.....
I have a 250Sec coupe in here with automatic transmission and the familiar idle speed solenoid but it has no throttle switch! I was puzzling over how this could be and searched the throttle mechanism for some other switch and I found it under the throttle pedal!
Neither I, nor any of my associates (with a combined experience of 130 years!) have ever seen this set up before and it doesn't feature on any parts diagram I have found.
I wonder if any of you have seen this arrangement before?

[Pawel66]

You mean: the three way solenoid on transmission or the idle speed solenoid?

I have never seen this kind of switch, but in case of me - it does not really matter, actually...

[stickandrudderman]

Well, if you're going to get picky, then both!

[Pawel66]

I was not! Might have been a different system I have no clue about!   

[Benz Dr.]

Probably not a factory set up. I've never seen anything like that; like ever.

[ja17]

I ran into this arrangement once or twice on some finback Mercedes sedans of the era.

[Pawel66]

I could only find this, but I do not know if this is what you are looking for as pedal looks different....

[stickandrudderman]

Well done Pawel, that is exactly the part that I couldn't find. Of course, it's not available but no matter, at least I know that it's original even if I've never seen one before. Thanks.

[Pawel66]

You are welcome!

I am still curious how this system works...

[stickandrudderman]

From the info on this site you will know that the three-way solenoid on the transmission and the idle speed solenoid on the inlet manifold are both controlled by the throttle switch on the throttle body; throttle closed (if you've adjusted the basic setting properly....!)=circuit made and power supplied to those devices.
This car doesn't have a throttle switch on the throttle body as normal, rather it has a switch under the throttle pedal so as soon as pressure is applied to the pedal the switch is opened in the same way as the switch on the throttle body would normally be.
This car had lost drive because the pedal has fallen off so the switch was always closed.

[Pawel66]

Clear now, thank you!

[Pawel66]

On availability you may want to check there, looks like they have the pedal, the switch is on request, but I bought some parts from them on request:

https://www.niemoeller.de/en/w112/mb-300se-w112021-coupe-m189985/B021/301001/


https://www.niemoeller.de/en/w111/w111-mercedes-benz-220sb/B012/300101/