Pagoda SL Group

W113 Pagoda SL Group => Electrical and Instruments => Topic started by: LindesayOne on May 29, 2025, 04:49:30

Title: Red/Purple Wire?
Post by: LindesayOne on May 29, 2025, 04:49:30

Hello Folks,

On my ‘69 280SL, if anyone can tell me what terminal this wire needs to be connected to it would be very much appreciated.

John

Title: Re: Red/Purple Wire?
Post by: BobH on May 30, 2025, 08:17:24

Hello John, i can't find this wire on any of the schematics, so looks like it may have been added.  I wonder if it's a ballast bypass, from the starter?  Has your starter been replaced with one, i think a 59X starter, that has a separate output for a bypass wire?

You can check if you get 12V+ve on the wire when cranking.  If that's what it's for and you still need the bypass, then it's connected to the +ve terminal of the coil, but please make certain that's what it's for before you connect it

There was also a bypass relay option, which used a +ve from the standard starter, but that required a 12V relay, and the contacts were used to bridge the ballast, i assume you don't have any additional relays that you can't account for?

If you decide you don't need to connect it, make sure it's well insulated and safe or disconnected both ends if you can find the source

Title: Re: Red/Purple Wire?
Post by: LindesayOne on May 30, 2025, 14:56:45

Thanks for weighing in Bob.
I recently removed a wire protected with a 15 amp fuse connected to the + battery terminal. I believe it was associated with an automatic door lock system which I’m removing piece by piece. So I suppose this R/P could be part of that system.
Anyway you’ve given me confidence that I can start the engine and if there are any issues this wire is probably not the culprit.

John

Title: Re: Red/Purple Wire?
Post by: lpeterssen on May 31, 2025, 00:09:43

Dear friends

That wire RED/purple came on later w113 and goes directly on POSITIVE COIL TERMINAL without passing through the external coil resistance.

Check out to confirm this affirmation that it will be powered ONLY WHILE CRANKING engine.

Best regards

Leonardo Peterssen
Www.wiredoktor.com

Title: Re: Red/Purple Wire?
Post by: lpeterssen on May 31, 2025, 10:56:53

John:

Line RED/violet can also be connected on the output side of the external coil resistance obtaining exactly the same effect of boosting voltage to coil while cranking the engine.

Best regards
Leonardo Peterssen
Www.wiredoktor.com

Title: Re: Red/Purple Wire?
Post by: clunker on May 31, 2025, 13:32:27

As @lpeterssen pointed out, this likely the additional wire that bypasses the ballast resistor at cranking time to the give ignition an extra boost - see attached annotated diagram from the technical manual.

Title: Re: Red/Purple Wire?
Post by: LindesayOne on June 01, 2025, 15:47:07

Many thanks, guys, for your definitive response.

Great to know, not only where the wire is to be connected, but its purpose.

John