[Floobydust]

My 2000 SL500 has recently developed an intermittent issue (now more often that not) where you can lock the car with the key fob but you can't unlock it. The lights flash when you press unlock so the key is transmitting and the IR receiver is receiving. And you can lock/unlock everything with the key in the door or the trunk, so it is not the vacuum pump module itself.

I think the issue may be a bad connection between the IR remote module and the lock/unlock line on the vacuum pump. Does anyone know where the remote module is located on a 2000 so I can inspect the connections?

Thanks!

 

[LewisMend]

Check the batteries before you dig too deep.

 

[Floobydust]

Check the batteries before you dig too deep.

Batteries are new. The problem is with both keys.

 

[sushipaste]

Same exact boat as you with my 01. For me It seems when the weather is really hot, then unlocking with the fob works, and so does the trunk release( I have to press down on the the trunk lid).

does your central locking button on the center console work for you?

 

[Floobydust]

I have the opposite issue - it fails when it is hot and sometimes works when it is cold.

Yes, the central locking buttons work as it should so there is nothing wrong with the locking system itself. It is definitely an issue with the interface between the locking system and the RCL module. I just have to find the damn module.

 

[Floobydust]

Well, I've been doing some deep diving on the net and found a couple of bits of somewhat depressing information. First, it appears that the IRCL module is hard coded to the engine ECU and so can't replaced with a used one and maybe not even a new one. Second, it appears the the R129 uses the same single line style vacuum pump at the W124 (which I also have) and that means that if the connection is flaky from the IRCL the locks would work completely or not at all. It also appears, but I have not verified, that the IRCL module is behind the driver's keen panel to the left of the steering wheel. Lastly, the trunk open feature does not work either.

So I conclude that either the IRCL module has failed or there is some sort of fault stored in the IRCL module that is preventing these two functions from working. Bummer.

Does anyone have any other thoughts?

Thanks!

 

[sushipaste]

Apparently this easy fix should could make the trunk release work, but only if the trunk releases when pressing down on lid while pressing the fob button

Trunk Pop Up FIX - 10 mins and no cost!

Hi everyone, Since owning the vehicle (3 months), the trunk button on the key remote and the trunk release button by the gear shift never did anything. Its supposed to unlock the trunk and raise it 2 inches. When pressing the buttons, I could hear the trunk trying to unlock, but it wouldn't...

www.benzworld.org

I will be attempting this

 

[Floobydust]

I bought the OBDII to 38 pin adapter for my iCarSoft for my MBII scanner and was able to access the remote controller and clear an error code which was "left door sensor open or shorted". I then went through the key re-sync procedure and it seems to work at this point. Who knows, just working for now or really fixed . . .

 

[sushipaste]

Keep us posted if functionality disappears again

 

[RDARoadstar]

Same exact boat as you with my 01. For me It seems when the weather is really hot, then unlocking with the fob works, and so does the trunk release( I have to press down on the the trunk lid).

does your central locking button on the center console work for you?

Mine is entirely different from both of yours dealing with temperature. Mine seems to work only when it’s dark outside, and in day light, I must be aiming from a shadowy place in order to get it to work.

 

[RKH]

That means your fob may have a weak battery or the IR lens (of the fob and receiver) may be dirty.

 

[Floobydust]

Update: The system worked for a while but has now become intermittent with unlocking again. Pressing the trunk button usually does nothing but when it does something, it locks just the passenger door! The behavior is the same with both keys and at all three IR sensors, and there are no additional codes, so I can only conclude that the IRCL module is failing. Bummer because replacement is a dealer-only affair involving huge quantities of Vaseline. Guess I will have to learn to use the key.

 

[Floobydust]

Just an FYI update, the IRCL for the R129 is NLA so if it stops working altogether I will have a very pretty brick in the driveway.

 

[sushipaste]

Just an FYI update, the IRCL for the R129 is NLA so if it stops working altogether I will have a very pretty brick in the driveway.

My door locks stopped working properly again lmao