Wendymomof2

Hello all! I've got a problem with my 1999 ML320. After returning from a 1400 mile trip I left my sunroof open and it rained a lot in my car.... Every since then it won't go over 30mph! I have been reading the forums and discovered this is called "limp home mode". My boyfriend has run the scan tool on it and the only fault codes that appear has to do with the O2 sensor. None related to the transmission. It won't shift into 3rd gear. It gets up to 30 mph and from there if I try to go faster the engine revs higher rpms but doesn't go into gear. What could this be? So far. We have changes the fluid. After some extensive research it seems like it could be the gear shift module? Or perhaps the auxiliary battery? What and where is the auxiliary battery? Any advise or data would be greatly appreciated. Thank you!

DrX

The rain caused a short circuit in your gearshift control module. The transmission was unable to determine what gear you had selected, so it defaulted to 2nd gear and refused to shift (limp-home mode).

Your boyfriend's scanner isn't high-powered enough to access the transmission codes. You need to visit an MB dealer or an indie mechanic who's good with Mercs (often advertise as Euro specialists).

To fix, thoroughly dry out your gearshift. Visit the workshop and have the codes cleared. If the problem recurs, replace the gearshift with a good 2nd-hand one from a wrecker's yard. Then you need the codes cleared again.

Welcome to the forum.

art_arev

The gearshift module is located in the console just to the rear of the shifter. The electrical contacts probably got wet. You have to open the console reach the module & dry it by any means asap. Otherwise you might need a new module

Wendymomof2

Thank you both very much for taking time out of your busy lives to post to my crisis. I will give this a try and post an update when I know more. I am so grateful that y'all offered your input. May God Bless you both. And I will post again soon. Have a Great Night!


Sincerely,
Wendy Hatfield

Wendymomof2

I took my car to the mb dealer and it cost me $190 to discover that the transmission control module and the actual shifter is bad... I was quoted a price of $2400! Can anyone help me? Can I change this myself?

art_arev

Have you dried your gearshift?
Dry it thoroughly first then have the codes cleared.
If it doesn't work you can replace it with a second hand unit.
You should have dried the gearshift before taking to the dealer & told them just to clear the codes. Of course they would like to make 2400 from you.....

DrX

Replace the shifter with a used one. They cost between $75 and $250.

Go to http://www.car-part.com, put in your year, model and in the Select Part section choose "Shifter Assembly (Floor)". It will come up with a selection of used parts and who has them.

Please note that you must replace it with one from a 1998 or 1999 ML. After that, the electronics were changed and won't be compatible with yours.

After you've replaced it, you need to visit a dealer or mechanic again to have the codes reset, to get out of limp mode.