Constant Idle Solenoid

[gcw206]

I have a problem that I cannot find listed anywhere in The Tech manual or in The Forum.  My CIS works on my 1969 280SL (w/o A/C), but it works in reverse:  It does not move the linkage when the car is put into gear, but does move when the when the car is put either "P" or "N".  This is backwards; it should engage when the car is put into gear, and then increase the idle speed to compensate for the increased loads, correct?  It idles smoothly at 750, but increases to about 1200 in "P" or "N" (also very smooth).  Is it possible that this device is wired incorrectly?  I checked the Site Wiring Diagram, but it states that is incomplete/incorrect as to "Idle Increase Solenoid" wiring.  Any ideas?

[220sebCoupe]

That's a strange one, the CCS relies on pressure from the transmission to earth out the circuit running to the CCS and make it operate, there should be power running to it all the time, but it wont function until the earth is completed by the pressure switches mounted either side of the trans. (one for reverse on the left, one for drive on the right - if memory serves). when the car is in P or N, can you push the CCS do-dad back and forth by hand? if it's functioning as you say you wouldnt be able to move this when in P or N??

[ctaylor738]

My understanding is that on 280s, the solenoid is only used to increase idle speed when the AC is turned on.  What you may be seeing is just the normal increase in idle speed when you shift into P or N. 

Can you actually see the little lever move when you shift into P or N?

[rwmastel]

CIS = Constant Idle Solenoid
CCS = Constant ? Solenoid
CSS = Constant Speed Solenoid

I think CSS is the most used term here, so when searching for help on this issue I would recommend using that term (either the acronym or fully spelled out).
http://www.sl113.org/wiki/Restricted/Linkage-tour#ConstantSpeedSolenoid