Fit door lock - 1990 Mercedes-Benz 300 Diesel

If you have a different key for the doors, try the door key.

Something broke inside door probably lock linkage rod inside door panel needs to be disassembled

Try spraying "lock ease" can get at parts house..spray and move key in and out.possible stuck tumbler..

factory fitted alarm/immobiliser,resetable with doorlock/key.not all fitted with interior sensors(different markets)to test lock (with drivers door window open)leave car for about a min then try opening door using inside door handle (pull lever).horn will sound intermitantly....to reset shut door and press lock button on remote.

some cars are fitted with autolock,car starts/car locks. some are fitted with driver masterlock button(above door switch panel)so the driver can lock all the doors/unlock for passengers to alight.but to stop you
locking the keys inside/you have them in your hand),car will not let you lock when in on position,keys in ignition/engine running etc.
so you do not have a problem.

the idea was to lock the car when moving(passenger safety,kids falling out etc),but it was too expensive to fit movement sensors,so,they fitted autolock,engine starts, car locks.simple......but sometimes a pain in the a???.

my 97 had the same problem. if the key fits the lock and will turn the lock but the lock wont open the door then your problem lies in the linkage between the door lock cylinder and the locking mechanism.

if the key fits the lock and the lock wont turn at all, this is what happened to me, then your lock is seized. Ive actually seen this on alot of 95-99 sentras it seems to be some sort of design flaw. what I had to do was to replace the lock cylinder and locate a new key. the locks from a dealer are a little pricy so i went around to salvage yards, every nissan sentra from said year range door locks were all seized, I even tried the 200sx as its the same car but a 2 door, same problem. luckily i found out that the 94 nissan altimas have the same door locks so I dismantled the inside door panel of said altima and snagged both front door lock cylinders. i also got lucky as the key was still in the ignition, replaced both locks and got a key for about 20 bucks. depending on your problem you might need new lock cylinders

lock may be seized!

ok easy first
unscrew all screws to the arm rests on the door
take off the surroundings
take out the clip for the window winder
till its just the door trim
then it will pop of
there will be a hard wire to the lock that unlocks it into a clip undo
and a clip to pull the lock out undo
then put new lock in same way put the clip o for the lock
then attach the hard wire
then reapply the door trim
and the rest