I am trying to get a concensus on what you think is the function of the glow plug relay violet wire (1985 300D). I have a light bulb A connected from violet wire to ground and another bulb B connected from the glow plug output to ground so i can see what's going on without having to deal with volt meters.

When the key is on, bulb B is on (i.e. glow plug getting power), bulb A is off. As I turn the key to crank, bulb A goes on and bulb B stays on (bulb A and B dims due to additional drain from starter motor). When engine fires and I release the key, bulbs A and B go off.

From this observation:

1. Is it behaving correctly?

2. What is the function of the violet wire?

My take from this observation is the violet wire resets the glow plug relay and removes power to the glow plugs once engine starts. Agree, disagree? Other opinions?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked