1988 300SE

My problem is that the duty cycle on the lamda reading is a constant 20%. I posted a question asking what this fault code meant.

ctaylor738 was kind enough to reply: "Full load switch incorrectly connected or faulty."

Since I had no idea what this item was he was once again kind enought to explain: "It's on the front outside of the air sensor assembly just above the intake manifold. I think it is black plastic and it has wiring that runs to a connector just to the outside of the idle valve. It's function is to tell the brain whether the system is at full throttle or idle or something in between. I believe that its main function is so that the EHA can go to "full enrich" at full throttle."

Of course I still can't find the thing. But, I figured, since this could be my rich running problem, I'd buy a new one and install it. Since I'd have the new one in hand, I hoped finding the old one one the car would be easier.

My problem is, no one seems to know what it is I'm trying to order. Does this part have another name? A strange situation that I'm in, trying to spend money but can't find anyone to take it!

Thanks for any help,
Ron Brooks

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Thanks,
Ron Brooks

Ron
MercedesShop (Fastlane) seems to have the right part,
part number here is C7014-12167. Here is a paste from the online catalog:

1988 Mercedes Benz 300SE
Part: Throttle Microswitch
Thrust Cut-Off
For use without Acceleration Skid Control (ASR) in later version cars. Fits



Product Brand List Price Core Ships

C7014-12167 Throttle Microswitch $24.50 $22.79 In 2 days


(Sure looks like the right part Ron, you can email Phil if you have other questions)

Gilly

Thank you! I saw that listing but didn't think it was the correct one. Now I can place my order and see what happens when I replace it.

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Thanks,
Ron Brooks

The full load switch would be part of the throttle switch. Not a lot of fun to replace. As the wiring is easy to get to and a switch can only do a couple things wrong, I would make it look open and see if it is the problem. Since both open and closed are acceptable positions the fault would have to be from a closed full throttlesignal while the idle switch is also closed.

You can try this with a new switch but it sure would be easier to do at the easy to access three wire connector just forward of the air horn.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician