Testing IR remotes
 

to test if any infrared remote control is working there is a very simple test you can do. most of us now days have either cell phone cameras or a digital camera, and theses units can be a useful tool to verify that all types of Ir remotes ranging from your television remote to the remote that unlocks the newer Mercedes cars.
what you do is power on the digital camera and look at the viewfinder, aim the remote at the camera and push all buttons individually, if the unit is working you will see a transmitted light, if you don't see the light from the remote output the unit is bad or the batteries are dead.
not sure why this works, but it does and has helped me many times to determine if a remote is actually functioning or not.

If the battery is charged and the RCL works, you can indeed unlock the doors by turning the trunk lock cylinder.

However, what if the RCL fails? For example, say that you left your car outside during a huge rainstorm and water filled the area below the back seat, shorting out the RCL. How are you to get into the car? The trunk cylinder is not going to open the doors in this case.

Sure enough I just tested this out with a TV remote and my little digicam and it works. I guess the digital camera is sensitive in the IR spectrum, good to know and it does prove you learn something new each and every day!

I still am not sure the remote on these cars work with IR or RF though...I know my smart key uses RF.

Good point...it is odd he didn't have a door lock cylinder at all - now I know why it is important to have one!

Recall a discussion with a MB salesman, this was on the subject of vacuum to control everything including door operation, I asked him why is MB still relying on vacuum despite never ending failures and everyone else has switched to electric, his response was that if you are in deep water and sinking,your vacuum based system will remain functional and will unlock the doors, with electric locks shorting you are locked inside the sinking car.

Vahe

I don't think that argument "holds water"...especially since all of the new cars use electric locks, at least our '04 does.

I attribute it to an innate love of things mechanical over electrical which is in the blood of the German engineers and their inability to change or admit their's is not the best way to do things. The strength of their designs were always in the steel not in the electrons. They have surrendered, finally, and accepted that electric locks are here to stay.

Having said that I prefer the almost silent operation of the vacuum system to the "clunk - clunk" of the electric locks.

Nope, it certainly doesn't "hold water."

Sure, there are vacuum lines to the doors. They come from the electric pump.

My Audi had vacuum operated central locking.

Personally I think its better because its nice and quiet. For a luxury car you don't want a "CHA-THACK" every time you open/close it.

i believe all use both IR and Radio, radio for distant activation and IR for close up activation.

The mystery continues.
Last week the remote stopped opening the doors, I was getting ready to take the car back to the dealer but then all of a sudden it is working again.
The only explanation that I have is that the problem was somehow related to the programming, I am assuming that as the key was inserted in the ignition it automatically re-programmed itself.

For now it is all ok and thanks for all your suggestions.

Vahe
240D/77
E320/97