Auto Transmission Pressure Switches

[bpossel]

Are the 2 pressure switches (one on each side of the trans) tied together?  :oops:   I left the wire attached to the right pressure switch when I removed the engine/trans 7 months ago.  My marking on the tape on the other end is gone, wiped off after some "Simple Green" cleaning... woops!

Thanks!
Bob  :oops:

[glennard]

Bob, Tied into the throttle switch and the constant speed solenoid?

[merrill]

Bob,

I cannot remembe for sure, however I think you are correct
I do recall a line connecting the pressure switches.
If you need I can crawl under the car and verify the wire colors and where they go.

This link may help.

http://www.mercedesdismantlers.com/16BoltInstallationInstructions.html

[bpossel]

Hi Matt,

If possible, could you do that?  I would appreciate it!!!!
Thanks,
Bob  

quote:Originally posted by merrill

Bob,

I cannot remembe for sure, however I think you are correct
I do recall a line connecting the pressure switches.
If you need I can crawl under the car and verify the wire colors and where they go.

This link may help.

http://www.mercedesdismantlers.com/16BoltInstallationInstructions.html

[graphic66]

They just connect together and go to the fast idle solenoid on top of the intake manifold. When you put the car into gear, one switch for forward, one for reverse, they ground out and activate the solenoid which has an always hot positive wire going to it. So by the pressure in the transmission grounding out the wire your fast idle switch is activated.

[bpossel]

Thanks David!
Bob

quote:Originally posted by graphic66

They just connect together and go to the fast idle solenoid on top of the intake manifold. When you put the car into gear, one switch for forward, one for reverse, they ground out and activate the solenoid which has an always hot positive wire going to it. So by the pressure in the transmission grounding out the wire your fast idle switch is activated.

[merrill]

Bob
I have attached the photos.
you can see that the switches are hooked together with the same wire then the green/red goes to the switch.

figured it would help all memebers if i attched these here


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Download Attachment: drivers side 2.jpg
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Download Attachment: passenger side.jpg
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[glennard]

Could you guys post the complete wiring diagram?  The double acting solenoid, throttle position switch, constant speed solenoid, kick down switch, et al interact with the tranny and FIP.  Have yet to find a BBB(not that it isn't there) explanation and diagram of how this all works together.  Many past post topics have nibbled around the fringe of the stuff.

[wwheeler]

That would be very nice to have as a reference much like many of the other "tours" found here.

BTW, why are there two pressure switches?

[merrill]

follow the mercedes dismantlers link and you will find the wiring diagram and troubleshooting tips.

This is the same diagram that is in the owners manual.

[bpossel]

Hi Matt,

Thanks for taking and posting the pictures.
This helps!
Bob  

quote:Originally posted by merrill

Bob
I have attached the photos.
you can see that the switches are hooked together with the same wire then the green/red goes to the switch.

figured it would help all memebers if i attched these here


Download Attachment: drivers sdie 1.jpg
157.41 KB

Download Attachment: drivers side 2.jpg
162.99 KB

Download Attachment: passenger side.jpg
142.66 KB

[glennard]

The mercedesdismantlers is diagram is incomplete. The throttle switch has two wires, not one as shown.  Other wires, etc are not shown definitively.  No wonder stuff doesn't work!

[bpossel]

Hello Glennard,

Thanks for you reply.  If possible could you please fill in the missing pieces?  Maybe explain which wires are connected where.
That would help me :oops: , but also I am sure it would help others...
Thanks Glennard,
Bob  

quote:Originally posted by glennard

The mercedesdismantlers is diagram is incomplete. The throttle switch has two wires, not one as shown.  Other wires, etc are not shown definitively.  No wonder stuff doesn't work!

[ja17]

Hello,

One pressure switch is for reverse, the other is for the forward gears.

[merrill]

Bob,
Hi, not sure what your ? is referring to.

unfortunately the only wiring diagrams I can find for the auto tranny are the same as the one from the mercedes dismantelers.com site.

the schematic is the same as the one in the owners manual and service manual.  I even checked the color coded schematic that the sl group send out a while ago.  the tranny is not included in the 230 sl schematic.


The pressure switches are linked together then to the green / red stripe wire.

[graphic66]

The pressure switches are linked together and then go to the CSS on top of the manifold. The CSS is fed positive power through fuse #5 and when either of the pressure switches are activated it grounds the CSS through the transmission casing to activate it. You can just touch a ground wire to the wire lug on the transmission switch and watch the CSS activate, I don't know if the fuse #5 is switched with the ignition key. It would just take a test light to see for sure.
  I guess it must be part of the design and I am sure there are reasons. But I think the pressure switches could be eliminated and you could run the CSS from the switch on the firewall that is linked to the shifter via cable. It stops you from starting in gear and turns on your backup lights. I believe it could easily run the CSS. I would like a 3 position CSS, one for in gear, one for the air conditioning and then a not activated position for neutral. You can link the AC to it now via a relay to switch the ground on when the AC pump is on. This can help in nuetral with the AC on, but in gear the AC can still cause a lower idle.
  What is missing on the  16 bolt site schematic http://www.mercedesdismantlers.com/16BoltInstallationInstructions.html  is the positive feed for the idling switch [#3] from the fuse #3. The idling switch feeds power to the double acting solenoid along with the kick down switch which is also fed power from fuse #3. Thus the three positions of the double acting solenoid. No power, power from the idling switch, and power from the kick down switch. The double acting solenoid uses the positive wire to switch it on and the CSS uses the ground to switch it on.
  Don't get the CSS, constant speed solenoid mixed up with you CSV, cold start valve, sometimes referred to as the CSS, cold start solenoid. The CSV is located on the manifold also but it squirts fuel into the manifold for a cold start and the CSS is on top of the manifold and it's sole purpose is to raise the idle when the car is in gear.