In pursuit of reducing the high idle speed my 1986 560SL had been experiencing, I determined that the Throttle Valve Switch (TVS) was bad. The test procedure is outlined in Service Manual document 07.3-152 "Checking, renewing throttle valve switch". The experience detailed below was guided by 07.3-230 "Removal, reinstallation of throttle assembly" and 07.3-225 "Removal, reinstallation of mixture control unit". Besides the new TVS, you will need a new Throttle Housing Gasket and perhaps a handful of new vacuum line rubber elbows. For additional cleanliness, buy a few cans of carburetor cleaner or your favorite degreaser. A shop vacuum would be practical as well.

For my preceding high-idle adventure, see the thread "Idle Speed Air/Control/Slide Valve Confidence Check" at http://www.peachparts.com/shopforum/showthread.php?t=243090.

In a nutshell, this job is not as bad as I thought it would be. In fact, I'll be doing it again soon, because of reasons mentioned below.

Break out the toolbox, 'cause here we go...