Don't know if I can help you much. From looking at my w124 and w126 cd.

30-Batt volt; hot at all time.
50-Starter motor control.
15R- Batt Volt; ignition/starter switch in "Accy"(pos.1), "Run" (pos.2) or "Start"
P30-Power feed for R and L standing lamps; Batt volt w/ ignition/starter switch in "off" or "Accy" position.
15-Batt Volt; ignition/starter switch in "Run" (pos.2) of "Start"
15X-Batt Volt; ignition/starter switch in "Run" (Pos.2).


30-R (Your RED)
50-VI/WT ( your purple w white stripe)
15R-PK/YL (your white w yellow stripe)
P30-GN/WT (your green w white stripe)
15-PK/RD (your white w red stripe)
15X-PK/GN (your green w white stripe)

PS,the scan quality on electrical diagram of my w124 cd is very poor. I can't make out the terminal numbers, so I have to look at the W126 cd (which is much better). I would use the VOM to check the voltage at each terminal( from the description of the terminals at the top)