Yes, another glow plug relay question. This one has pics!

I have a '72 w114 that has a '76 300d conversion which I did not do. This vehicle has the "old style" glow plug relay with the pencil style glow plugs which are wired in parallel. Someone extremely generous has sent me an '81-85 300d/300sd glow plug relay that will properly power my pencil style glow plugs.

Questions:

What wire goes to the "La" plug on the relay?
What does the violet wire do for this relay?
What does the black/green/blue wire do for this relay?

My understanding is:

30=red/black=power in
31=brown=ground
50=violet=?
15=black/green/blue=?
G1=glow plug 1
G2=glow plug 2
G3=glow plug 3
G4=glow plug 4
G5=glow plug 5

Thanks in advance for everyone's help. Yes I have spent hours searching. If I have missed an obvious link, please let me know.

Thanks,

Dave

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The violet wire connects to the ignition switch and turns off the glow relay when you release the key after cranking the engine. Otherwise the relay stays on for the full 30 seconds. If you still have the original ignition switch, you may not have that contact. An ignition switch from a later model 300D would give you the contacts you need. I don't know if such a switch will work with your existing lock cylinder; it would be nice not to have two keys.

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Nice, 1 question down and 2 to go.

I have the correct ignition switch for the '76 300d engine. The one that has the vacuum line fuel shut off.

Thanks

Starting to figure this out.

30=red/black=power in=same as old one
4=31=brown=ground=same as old one
3=La=preglow indicator lamp
2=50=violet=starter lockout=same as old one
1=15=black/green/blue=preglow time relay=same as old one


Current preglow indicator lamp has a black and a brown/green wire powering the unit. Since the new relay has an internal temperature sensor the schematic shows a black wire and the other one going to ground.

New question: Can I hook up the black wire (the one on my preglow indicator lamp) to La and ground out my brown/green?

Also, I am assuming that I need to disconnect the wire for the coolant circuit sensor. Is that correct?

FYI in the first pic #2 is the preglow indicator lamp and in the second pic #4 is the preglow indicator lamp. First pic shows the lamp with black and brown/green wires. Second pic shows the lamp with a black wire and other side grounded.

Thanks for reading

Dave

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