justinmorrison

Good evening everyone,

My 550 is keyless go equipped, and on 3 of the four doors, I can unlock and lock the car with the key in my pocket by touching the appropriate place on the handle.

My rear driver's side door, however does not work. I'm assuming it's not a fuse, since 70, 71, 80, 81, 82, and 131 also apply to other systems (which work), and since 37 is the only fuse that is unique to keyless go, I think it's safe to assume that it doesn't apply to only one door.

I pulled the door handle to verify that the wiring harness was plugged in (it is), so I'm not sure where to go from there. I suppose I could pull the door panel and verify that the rest of the wire to the handle hasn't been pinched/severed.

So either a. the handle is defective (which seems odd), or b. there is a disconnect somewhere. Any suggestions on where to start?

wywywywy

The capacitive sensors on these handles die all the time unfortunately!

alx

Standing in front of the driver's door try to unlock the rear door. Success? It is the antenna for the rear driver side - short or dead altogether. Failure? It is the handle. You can also heat up a bit (just a little) the handle with a hair dryer. If it starts working it is the handle.

There is also an update for keyless go that addresses intermittent keyless go problems

justinmorrison

Thanks for the info Alx. I held the key up to the driver's door and tried to open the rear door with no response. Also tried opening the door while holding the key in the same hand, again, no go. So it sounds like the handle is dead. It's somewhat humorous that a part that was at one time 100% mechanical can be defective, despite still being fully operational (from a mechanical perspective).

Assuming I locate a compatible (and working!) handle, is it plug and play, or would I need coding as well?

Prash

How did you get on with this?
Did replacing the handles work and did it need coding?


Both my front door handles do not work, but both rear door handles work fine and open the car with the key in my pocket.

justinmorrison

I haven't had a chance to work on it. Since it's not the driver's door, it's pretty low on the priority list. I probably wont get to it until after September the way my work schedule is going...

xpl0sive

anyone know how to replace the keyless antenna modules? are they inside each door? 3 of mine are dead i figured out.

xpl0sive

Bump. Anyone know where the antennas are located? I ordered new modules just need to figure out where they go now lol

konigstiger

Rear door antennas (forward, top): http://www.ebay.com.au/itm/07-08-09-...-/291300386754
Panel removal: http://workshop-manuals.com/mercedes...nt/page_19932/ + next page

KG control module: http://workshop-manuals.com/mercedes...ns/page_19189/ + next pages

xpl0sive

Thanks for your reply. Does that mean there are no antennas in the front doors? I had a look as WIS and it seems to say that there are.

konigstiger

Post the doc, EPC capture previously posted is for MY07 s550 showing only rear door antennas.

xpl0sive

here's the keyless go components doc. Your docs are correct, sensors only in rear doors. There are also two sensors inside and one in the trunk

xpl0sive

I tried replacing the antennas in the doors, did not solve my issue. Also tried new batteries in the key, still no resolution. All door handles respond as they should. I can see the cluster light up when I touch the handle to unlock the car. It displays the message "Key not detected".
I checked error codes with STAR for keyless go. Got the following code:

"Component A2/12 (Rear window antenna amplifier module) or line to component has short circuit or open circuit."

From what I understand, that module is for radiot/nav/phone. Does it have anything to do with keyless go antennas?

xpl0sive

well looks like I've found the answer to my own question. Just had to keep looking in WIS Net
Here's the doc for the rear antenna module. Looks like it processes the keyless entry signal as well. It actually uses the rear window heater as one big antenna...