Author Topic: Mystery Switch  (Read 4270 times)

rbrownie

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Mystery Switch
« on: February 06, 2008, 01:31:36 »
I have a 1970 280 SL.  I am trying to understand the various switches and electrical things that control the fuel and emmission control.

There is a screw-in plug in the side of the engine block just below plug #6. It has two wires which I think go to the cold start injector.  Half way down the block below plug #5 is another screw-in  switch with only one wire capability.  It has nothing connected to it.  What is it and what does it do?  What is it supposed to be connected to?

Thanks

Roy
« Last Edit: February 07, 2008, 22:37:17 by 280SL71 »

al_lieffring

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Re: Mystery Switch
« Reply #1 on: February 07, 2008, 19:21:48 »
The upper switch is called the Thermo Time switch. It engages the  injector solenoid on the intake manifold via the relay on the left fender well by the safty latch, when the starter is engaged. the colder the engine temp the longer the duration of the injection.
The lower temperature switch is for cold start ignition timing advance, When the engine is Below 17deg C. this switch connects to ground and signals the timing controll relays, the two black boxes on the left of the motor by the battery, to release the vaccuim retard, thus advancing the timing for improved fast idle speed when the motor is first started.

Al Lieffring
66 230SL
« Last Edit: February 07, 2008, 19:23:32 by al_lieffring »

Peter van Es

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Re: Mystery Switch
« Reply #2 on: February 12, 2008, 08:51:42 »
Check the Technical Manual: http://www.sl113.org/wiki/pmwiki.php?n=Engine.ThermoTimeSwitch

For how it all works, check this:

http://www.sl113.org/wiki/pmwiki.php?n=Main.Engine-starting-aid-tour

Peter

1970 280SL. Also known as 'admin@sl113.org' and organiser of the Technical Manual.
1970 280SL. System Admin of the site. Please do not mail or PM me questions on Pagoda's... I'm not likely to know the answer.  Please post on the forum instead!

Benz Dr.

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Re: Mystery Switch
« Reply #3 on: February 12, 2008, 18:40:45 »
Al kows his stuff.  Why, I bet he knows almost as much as me. ( lol )  

( I wonder if he's looking for a job..... )

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