1992 500sl shift problems

[jmtaylor75]

My SL just started late shifting in all gears. To shift into high I have to let off the accelerator, it shifts, and as soon as I touch the pedal it down shifts. Is the shifting electronically controlled or vacuum controlled? It also has a limp mode problem. Could these be connected.Any help would be greatly apprieciated.

[tecqboy]

There is a fuse on the OVP relay ( Over Voltage Protection ) which may have blown and could be the cause of your problems. The OVP relay blows the fuse to prevent an over voltage spike from damaging other electronic components. The OVP relay is located under the hood on the US passenger side of the vehicle under the plastic cover just in front of the fire wall adjacent to the cabin air filter cover. There are 4 large philips screws holding the cover in place. The fuse is a blade type right on top of the large plug-in relay. Check the fuse. And then of course, your problem could be caused by something entirely different ( like ASR or ABS ). Good Luck. The transmission in this vintage car is mechanically controlled; vacuum and pressure.

[RadioTek]

You may have to spend some time looking for a vacuum leak. Check where a tube goes around a bend, where it may be near a heat source, or at a connector. If you have any of the hard plastic tubing, beware that it tends to shatter when looked at carefully.