Everything you need is on the zsmaster site. Search for it.

There are electrical troubleshooting capabilities you can load from there. I ran my Eds troubleshooting from that.

The w140 is a complex beast, but the diesels aren’t that bad when you get an e-FSM from eBay for like $10 and/or use zsmaster site.



The IP idle control plug is red IIRC. It’s a different length than the others that may be like it (temperature sensor?).

Here are some screenshots from harness and Eds testing:

https://www.peachparts.com/shopforum/diesel-discussion/415181-om603-971-eds-codes-diagnosis.html

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
2008 ML320 CDI (199k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)