C146 is the auto transmission NSS connector.

According to the ETM, there are 4 pins.
Pin 1 - blk/yel/red - +12 V from F14 for reverse light supply, this is double tapped at C146 with a blk/red to the kick down switch. Obviously you will not be needing this any more.

Pin 2 - gry/yel - to reverse bulbs, this goes through the big C104 under the dash that carries all the trunk wiring.

Pin 3 - vio/wht - from terminal 50 on key switch (pos III)

Pin 4 - two vio - thinner one to GP relay, thicker one to pilot terminal on starter.
Remember when you start you have to hit the starter solenoid as well as the GP relay.

How does a manual turn on its reverse lights? At the transmission or is it part of the shifter? The ETM shows a jumper on 3 and 4 for the start interlock and a switch for reverse lights but is vague on the details.

__________________
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