Everytime i press down the button to lower the window the door lock.

no info generic answer remove door panel and examine the latch and linkages

Try resetting one touch as outlined in the owners manual.

"Functionality may be lost under low battery power conditions.

To reset this function after restoring full battery power:

1. Pull the switch to the one-touch up position.
2. Hold the switch until the glass reaches the stall position and continue to hold for two seconds.
3. Press the switch down and operate the window to the full downposition. One-touch up will now be functional."

What's FX4 ? How many door's ? Do the other door switches have battery power ? Can you test this with a volt meter ?

Principles of Operation
The left front window switch may be used to raise or lower all windows, or each individual side window may be controlled by the control switch located on each door panel.
The instrument control module (ICM) controls power to the power window system by activating or deactivating the delayed accessory relay.
The one-touch down feature will completely lower the driver side window when the master control is fully depressed, then released. The one-touch down feature is integrated into the LF window control switch.
There are 2 modes of LF window down operation: manual mode and auto mode. The manual mode is selected by pressing the LF window control switch to the 1st (DOWN) position. In manual mode, the window will move downward only while the switch is depressed. When the LF window control switch is pressed to the 2nd DOWN position, it enters auto mode and the window will open completely with a momentary press of the switch.
When the one-touch down feature has been activated, it will stay on until one of the following conditions is met:

• The LF window control switch is pushed to the UP position.
• The LF window control switch is released (OFF position) and then moved to the DOWN position (1st detent) or ONE-TOUCH DOWN (OTD) position (2nd detent).
• 7 seconds have elapsed since OTD was initiated.

Window operation is enabled whenever the delayed accessory is active and the LF window control switch is pressed to the UP or DOWN position. The switch provides delayed accessory power to one side of the motor and ground to the other side. The one-touch down feature is not active when the LF window control switch is in the UP position.
Passenger windows may be raised or lowered using the LF window control switch or the appropriate passenger window control switch. Passenger window control switches receive power when the delayed accessory relay is active and the LF remote lock-out switch is in the UNLOCK position. When in the LOCK-OUT position, the passenger windows are deactivated.
The delayed accessory relay provides power for the operation of the power windows and the power roof opening panel. The delayed accessory relay is active whenever the ignition switch is in the RUN or the ACC position, or when the ignition switch is changed from RUN or ACC to the OFF/LOCK position and the LF and RF doors are closed.
The ICM will deactivate the delayed accessory feature when:

• The LF door is ajar and the ignition switch is in the OFF/LOCK or KEY-OUT position.
• The RF door is ajar and the ignition switch is in the OFF/LOCK or KEY-OUT position.
• 10 minutes have elapsed since the ignition switch was changed from ACC or RUN to the OFF/LOCK position.
• Symptom Chart Condition Possible Sources Action
  • All power windows are inoperative
  • Fuse(s).
  • Circuitry.
  • Instrument cluster module (ICM).
  • Accessory delay relay.
  • Driver window control switch.
  • Go To Pinpoint Test A .

Check the fuses in the fuse box.

Most likely needs to be re matched to the car.

Two bits of info off the net for you

C CLASS (1993-1997), E CLASS (1995-1997), SLK (1996-)
Procedure
1. Point the remote control at the receiver - this should be located in the driver's door handle or next to the boot lock button.
2. Press the lock/unlock button.
3. Within 30 seconds manually lock or unlock the vehicle using the passenger's door lock or the boot lock.
Alternative method
Procedure
1. Point the remote control at the receiver - this should be located in the driver's door handle or next to the boot lock button.
2. Press the lock/unlock button.
3. Within 30 seconds, switch the ignition ON.
Alternative method
Procedure
1. Point the remote control at the receiver - this should be located in the driver's door handle or next to the boot lock button.
2. Press the lock/unlock button.
3. Within 30 seconds, turn the ignition switch to position II.


and

1. Place key in ignition lock and turn to position 2 [all ignition lights on]
2: Turn key to off position and remove from ignition.
3. Within 10 seconds:
3a: press the Close [Lock] button and hold it down
3b: while the Close button is still depressed simultaneously press the Open [Unlock] button. Press and release the Open button 5 times [still holding the Close button down]
3c: Release both the Close and the Open buttons at the same time, and immediately push any of the two Open buttons once [i.e. either the Open doors or the Open Tailgate]

This information is for the resetting of a previously synchronised key to match the security system after batteries have been removed or replaced. This information does not work with new keys which it seems must be taken to a person with a key synchronisation device [or a super-ripoff-expensive MB dealer]

hope this helps

unlock with key and hold key over for 30 secs(windows may go down)then lock with key and hold over for 30 secs(windows may go up)then press remote unlock button and hold for 30 secs,you have just reset system...the closer you have to get to the car for the remote to work the lower the battery power.sensor on top of dash(little black dimple)rarely,if at all, goes wrong.....

reset the central locking system by locking car with key in drivers door and hold key over for 30 secs.then pressing and holding down unlock button on keypad OR unlock door with key and hold key over 30secs (windows may go down, thats okay,some cars are fitted with auto windows)then press and hold lock button on keypad.making sure that in both cases you know the keyfob battery is in good nick....should reset system

sequence for freelander lock unlock, to lock 1press = door lock , 2press = door dead lock , to unlock 1 press = driver door unlock, 2 press = passenger doors unlock, also rear window can be operated from fob to do so press and hold unlock button for 3 or more seconds and rear window will roll down.neat feature.hope this helps

sequence for freelander lock unlock, to lock 1press = door lock , 2press = door dead lock , to unlock 1 press = driver door unlock, 2 press = passenger doors unlock, also rear window can be operated from fob to do so press and hold unlock button for 3 or more seconds and rear window will roll down.neat feature.hope this helps

Could be a relay for that door..
Or it could be the auto lock motor for that door.