[dreamhope]

I've been trying to fix the KG on my newly acquired 2005 S500.

Borrowing C6 from the local shop when I did the engine + trans mounts, I was able to verify that the keys are correctly assigned as KG tracks (one wasn't, and I rectified that).

Still, I only get "Key Not Recognized" when using the Start button.

I've also verified that the wiring to the module is correct (originally the black wire to the trunk antenna was disconnected, probably during a battery change).

I see several possibilities:

• One or more door antenna disconnected or missing (I guess the left rear door has been replaced, though I'm not sure)
• Some in-cabin wiring is not correctly connected (car interior has been refurbished, and the rear ac control and TV connectors had been wrongly connected to each other. I've rectified that issue)
• Keys are bad

So will KG work with a door antenna missing, at least somewhat?

As a side note, is there any version of Xentry Passthru that will work with this car?

Thanks

 

[Kammie]

Yes it should work, mind you; only time when I see that message (keyCARD not recognized) either my keycard is in the same pocket as my phone or the batteries are dying. I also remember one time someone got in my car while it was running and drove it away from me while I had the key/keycard in my pocket, he parked it and locked it with the door button. The car went in to some sort of anti theft mode, keyless didn't work, I had to start the car with the key in the ignition one time.

 

[dreamhope]

After more fiddling, I think either the keys are bad or the KG module is bad.

I saw in another thread where TiffanyTwisted wrote that when you push the Engine Start button there should be a quick succession of audible coil whine from the antennae. I tried a dozen times but can't hear anything. --> This could possibly mean that the KG module is bad. I guess a used one may fix that.

Then, the keys could be bad. One key I have is one of the original two (Track 1). I guess it's possible that its copper coil is desoldered / broken. The other key is a replacement. I think it's an original MB key, but I don't know if its KG or not. While it's unlikely that two keys have both had KG function died, it's possible that Key 1's KG died and Key 2 isn't KG to begin with. [edit: Key 2 is one of those "Gen 4" chrome keys, so virtually impossible to open.]

I'm getting a used C4 to test further (and to help with diagnosing the car when needed in the future).

 

[dreamhope]

Another update:

I ran more tests with DAS. This time, I heard the audible sound when using "localisation of keyless go key" (or similar). Unfortunately, no key was found by the car.

Does this mean that the two keys are both bad?

I know that the Overhead Control Panel has problem with the temperature. There's also a P0400 code for EGR.

 

[dreamhope]

One more update:

Bought a used KG module. Same symptoms. Returned.

Now I'm certain that the original black key is bad. The other, replacement key is the Gen 4 chrome variant that probably isn't compatible with the old KG system.

I'll see if there's a repair shop that'll look at the PCB.