slk320 transmission with not shift out of first gear going forward..reverse o/k

For the most part, automatic transmissions use what is called a "Vacuum modulator" in order to shift gears, but some luxury cars use an electrical switch (E-Gear, Tiptronic) which gets its information to change transmission gears up or down, based on sensor information fed to the ECU (Engine Control Unit). The ECU takes into consideration the RPM's of the engine (based on the distributor or timing sensor rpm's), the speed of the driveshaft (based on the cruise control sensor), and numerous other sensors to determine if a shift is required at the time. Take a look and see if you have a vacuum modulator or an electrical switch to shift gears and replace that first, since it is cheaper then my next thought. If there is a burnt smell from the transmission fluid or the fluid looks brown and not red you might need a new transmission.

You state it does the same thing in "manual" mode, so I'm thinking you should just get the cost of a rebuilt transmission and save yourself the time and hassle of replacing the switch.

Look for shift indicator on cluster to see if it changes while moving shifter with key on. If position is not showing then shifter ain't putting out a signal. Replace shifter. No programing required on a used one.

@fordtudor37 I have been having the same issues with my Mercedes 2001 SLK 230 My car gets stuck in dirt gear and will not shift to second so stays stuck in 40mph. I have taken it to the dealership and they are trying to charge me so much money for what seems is an easy fix for them. They told me I have a faulty speed sensor. I don’t know what to do or how to get this issue fixed. My father is dead set on just getting a new transmission from auction online to try to fix the issue. However I am not sure if that is the answer.

its a plug near the brake line in under hood drivers side near where the wheel wheel meets the dash fuse box area .....is ur abs and ESPN lite on.....if so text me

Yes it is