Idle Control Switch repair

[WRe]

Hi,
does anyone know the inner workings of the idle control switch and know how to repair it if necessary, which according to Niemoeller should be possible under certain circumstances (see https://www.niemoeller.de/en/search/000%20545%2033%2004)?
...WRe

[Pawel66]

I have not tried it, but can imagine it may be a points replacement. There is a lever on pivot, a spring and two points. Also plastic part the is moved by throttle pivot and moved the lever.

Points may be difficult to replace as they are riveted to the brass connector bar...

[wwheeler]

I have actually sent in a switch and received a "rebuilt" one. I sent mine to the US Classic Center. Looking at it, it looks brand new. They must use certain parts and the use other new parts. That was a few years ago and maybe they ran out of new ones and are really rebuilding them now. Not sure. I have taken these part many times and not much to replace easily. A couple of gaskets, a seal and clean the points. That is about all a DIY can do. On an untouched switch, the screws have been peened so they won't work loose. Not hard to get them out though but is resistance at first.

The points look to be pretty stout and I have never seen one where the points were fried. I wonder if the current point material is as good as the originals though. That switch cycles a tremendous amount during normal driving and especially the city. Think about it, every time you let your foot off the gas, the switch closes and activates the trans solenoid. It adds up quickly.

[WRe]

Hi,
I dismantled and cleaned the switch because it was very dirty which was no rocket science.
See Technical Manual: https://www.sl113.org/wiki/Automatic/Start#ThrottleSwitch
...WRe

[Pawel66]

Hi,
I dismantled and cleaned the switch because it was very dirty which was no rocket science.
See Technical Manual: https://www.sl113.org/wiki/Automatic/Start#ThrottleSwitch
...WRe

Me too. i also had to fix the threads for the contact screws. For vicinity of USD or EUR 400 you can just buy a new one, then have yours cleaned up by yourself to go on shelf for emergency. i think more value would be there if the points are changed.

I think it may be the time to install the relay wiring, if the points are getting worn. It has been discussed and advised and is not particularly difficult to do. Perhaps hiding this wiring is more of a challenge so that it is not seen under the hood.

[gordon]

I'm not wishing to hijack this thread but can someone confirm that my throttle switch will be redundant on my now manual (from automatic transmission) 230 SL

[WRe]

Hi,
yes, only automatic transmissions need a throttle switch.
...WRe

[wwheeler]

I did install a relay for the trans solenoid to try to take the load off of the throttle switch. It worked for quite a while and then the relay started giving me trouble. I think the points in the switch are actually stronger than in the relays. Looking at both, the switch’s points are larger.

I have had issues over the years with the switch working and then slowly over time start to fail intermittently. Then you get harsh downshifts. I think it just works too hard given the switch’s design. Seems like there could be a better and longer lasting design. Someone had suggested using dielectic grease to reduce the amount of arcing on the points.