500 sel idle speed control unit location
 

Hi all.
I have a 1983/1984 500 sel which was imported in Australia and have high idle issues which i believe is a common thing.I have tried changing idle speed control valve,fuel pump relay and over voltage regulator but still no good ,next is will be idle speed control unit (electronic box) but it is not situated in the fuse box according to manuals i have .Can somebody tell me where its located.
contact me on
paulpic1@exemail.com.au

It's a big black box that is about 4 inch x 4 inch by 1/2 and sits on the firewall on a w126.

looked there but to no avail,i finally found it under the dash behind steering column and firewall (RHD) ,what a job to change it.
Thanks for reply anyway.

There are a number of posts on how it can be repaired. Often some of the solder joints fail, and can be renewed by heating with a soldering iron. Especially vulnerable are the large joints at the main plugs. A couple of mine had failed. Today I pick up my new idle control valve, which will, hopefully, mark the end of my car's idle problems!:DNed

after changing the unit it cured my idle problem so decided to pull the old one apart,i found a few hot spots on the circuit board which apears to be a failed diode and some sort fet,transistor or something.