I can't lock the doors from my driver side door lock.

I have to walk over to the passenger side to lock the doors but I can unlock them from the driver side.

I have sprayed "liquid wrench" into the lock hoping to free it up with no luck.

Is there anything else I could try short of getting new locks/ignition?

__________________
1993 W124 300D
-297K on the clock as I type this.

Did it ever work before ?

To diagnose the problem you will need to completely remove the mechanism.
The same path you would take to replace it anyway.

So you will be halfway there. Disassemble it and study it.

I fixed mine this way.

__________________
80 300D 340K Owned 30 yrs
83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day
02 Z71 Suburban 117,000
15 Toyota Prius 2600 miles
00 Harley Sportster 24k
09 Yamaha R6
03 Ninja 250

When you say, "I can't lock the doors from my driver side door lock," do you mean

1) the key won't turn in the lock direction, or
2) the key turns but nothing happens.

If (1), it is probably the lock cylinder.
If (2), it is probably the switch or a wire.

Either way, you will have to remove the inner door skin and check out the mechanism. Broken wires as they pass from doors through the rubber boot into the pillar are common in this car. The "lock" wire in the driver's door is brown, the "unlock" wire is red/white, and the common wire is blue.

BTW, can you lock/unlock from the trunk?

Jeremy

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

The key won't turn in the lock direction.

Yes, I can lock the doors from the trunk.

__________________
1993 W124 300D
-297K on the clock as I type this.

OK, so it's probably the lock mechanism. Rhodes is right, you gotta take it out and take it apart to repair or replace it.

There's a slight possibility that the key is worn. However, that should cause problems in both directions and in the other locks. Just to confirm. do you have another key you can try?

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

No, but I was going to get one made to see if that was the problem.

__________________
1993 W124 300D
-297K on the clock as I type this.

I have a 1995 E320 Cabriolet and I have similar problem. I can unlock both doors from drivers side, but cant lock passengers using key in driver side.

TIA

Lou.

There are threads on rekeying. Pulling the cylinder will give the necessary information.

osprey you need to pull the part holding the barrel from the door , and file the tumblers down to the same level as they wrear the tumbler segments get higher in the barrel and wont turn . Open the door you will see rubber grommets you have to remove the one thats in line with the handle .Inside is an allen screw holding the lock part of the handle in there. Dont remove it right out or the screw will fall in the door .Only screw it about 4 turns .Then with the key in the lock turn it left to right till it comes out. I will see if i can find a diagram .

This is what you need to do once its out.

Attached Thumbnails

 

Maybe yes, maybe no. A more complete writeup on door lock cylinders:

Repairing Mercedes Door Locks

Different models will have somewhat different lock cylinderss, but the idea is always the same.

The bad news is that this condition can also be caused by a problem with the lock mechanism itself (the part that stays in the door after the cylinder is removed. If adjusting the cylinder doesn't work, the next step would be to pull the lock from the door to inspect/repair or replace, and that's not an easy job.

Without seeing the fault its hard to say .
I can only speak on the lock in my door and how i solved it .
Still works to-day .
A new barrel is the best way out if you can get one without wear in it Or a new one
And if there were a problem with the mechanisim in the door it would not open from the other side with the key. .All looks like the barrel to me.