Author Topic: 1969 280sl Starter wiring  (Read 2283 times)

edwardburak@erols.com

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1969 280sl Starter wiring
« on: July 19, 2021, 16:36:26 »
I have a 1969 280SL US version. I am installing the wire harness to the motor and now am stuck on the starter.

As you can see in the photos, I have one thinner gauge gray wire (T50) and one thicker gauge red wire (T30). Along with the positive battery cable which is not in the photo.

I have my old starter out of the car so I am using it in the photos.

I know that the positive battery cable belongs on the large post on the starter solenoid, signaled by my red arrow in the photo.

I think that the thinner gauge gray wire goes on the small side screw on the solenoid, signaled by my gray arrow in the photo.

Based on the diagram I found on this site, the red wire belongs on the same large post on the starter solenoid as the positive battery cable. This makes sense to me as that red wire is connected to the alternator and is where the alternator sends its charge to the battery. That diagram is however for a 1970 and mine is a 1969 I assume that starter wiring would be the same, but I may be wrong.

However, the red wire eyelet connection is too small to fit over the large post on the starter solenoid.

I read on a forum chat that the gray wire is connected to the neutral safety switch. I checked mine with a continuity tester and it is correct.

the red wire eyelet is bigger than the gray wire eyelet one, so it would not make sense for those two to go on the same smaller side screw.

If necessary I will either drill out the red eyelet or crimp on a larger one, but I would like to know where it belongs first.

If anyone could could help me, it would be greatly appreciated.
thanks
 

WRe

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Re: 1969 280sl Starter wiring
« Reply #1 on: July 19, 2021, 18:12:57 »
Hi,
the red cable usualy comes from generator B+ to starter T30 same with black cable from battery.
...WRe

lpeterssen

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Re: 1969 280sl Starter wiring
« Reply #2 on: July 19, 2021, 19:19:33 »
Dear friend

Quite easy.

As already said by WRE T30 thin cable (coming from alternator) and BAT+ Cable coming from battery go to the same bigger post which should be market either as T30 or BAT+ in your starter. 

T50 cable which usually is gray or violet on some other mercedes is the signaling from the ignition switch to crank the engine.  In automatic cars this cable passes through the parking/neutral safety switch on the firewall next in the first half of the engine wide.

In some modern starters there is a third small cable post labeled T16 which is in parallel  with T30 when T50 is active in order to bring a stronger 12V signal to the ignition coil (+) terminal bypassing the coil external resistance only during the cranking.

Best regards
L.peterssen

edwardburak@erols.com

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Re: 1969 280sl Starter wiring
« Reply #3 on: July 19, 2021, 19:47:52 »
Thank you for your clarification, I will Make the corrections on my starter

edwardburak@erols.com

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Re: 1969 280sl Starter wiring
« Reply #4 on: July 19, 2021, 19:48:11 »
thanks for the help