I was going off the ETM But it's kind of vague. I'm just speculating since I have never seen a M/T 123, but what D911 said, makes sense to me on how it would be logical to arrange it. The main vehicle harness has a plug above the accelerator. A sub harness, used only for A/T, picks up from there, and goes to the NSS and kick down. For M/T a different sub harness would be used for the shifter reverse light switch, with the NSS jumped out in the plug.

If that is the case it ought to be plug and play if you have the proper M/T switch and harness.

I don't know for sure but given the other examples of the way these cars are wired it makes sense to me that it would be set up like this for ease of assembly.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech