Emission Control Wiring

[dwsfca]

I have the Haynes manual and a BBB but still have not been able to determine the exact circuit wiring for the Emission Control system on a 1970- 280 SL.

Much of what I have is through research of past posts, especially Jeff C. (thank you) and a few others who have had issues with this system.

Hopefully some of you can help me complete the diagram I am providing (SEE ATTACHED)

I have no information on specific connections to the Current relay.
I believe that the 2 way valve is connected to it but I do not know which terminal it connects to.

I also need help with the Relay Box connections.

Any help would be greatly appreciated.

Thanks,
Dan W.

[jeffc280sl]

Hi Dan,

I think this diagram is in both documents you have.  I cleaned up the noise around the top of the connector so that you can see the interconnectivity.  It's been a while since I looked at this stuff but I think my diagram is accurate.  Let me know if you have any questions.

[jeffc280sl]

Here is another wiring diagram of the emission system relays.  It should agree with what I sent you earlier.

[Peter van Es]

Also always check the Technical Manual: http://www.sl113.org/wiki/Electrical/WiringDiagram

[dwsfca]

Jeff thanks for the info, my Haynes manual is not very clear(hard to read the diagram).  The cleaned up version you sent has led me to diagnose a bad speed relay and bad 2 way valve. The 2 way valve can be made to engage with a jumper (you can hear it engage, but it does not shut off the vacuum to the retarder).

Is it repairable or are replacements available?

Peter, thanks for the tech manual info.  I did check my BBB but I own a 68-250 SL and my BBB does not have 280 SL info.I did not realize there were different manuals. I purchased the manual back in 1981 when I purchased the 250 SLfrom the original owner.

Thanks again to both of you and this group.

Dan W.

[jeffc280sl]

Dan,

I asummed you had a 1970 or 1971 280SL.  The wiring diagram and components you mentioned certainly led me in that direction.  But you say you have a 1968 250SL.  I wasn't aware they had any emissions control stuff on that car.  Attached you will find the emissions stuff for a 1968 280SL.  Your system should look more like this control system than the later 70/71 versions.  How did you come by having a 280SL 70/71 emission system installed on your 250SL?  There must be an interesting story there.

You can buy new 2 way valves.  I'm told that the speed relay can be repaired by Beckman Industries in Durham, NC

[dwsfca]

Jeff,

Sorry for the confusion.  I am working on a friends 1970-280 SL and that is what I needed the information for.  My car is a 1968-250SL and it has only what came on it in 1968.  As far as I can tell there is no emission control other than fuel cutoff when decelerating. Thanks for the 68 info , I will check over my system also.

No interesting story here.

Thanks again,
Dan W