wlmteng

Hello,

I have been trying to find a post with similar problem with mine but no luck. Please advise. Thanks in advance.

My 2006 S350 (W220) keyless Go is not working, here are the symptoms (every day in the morning):
1. Touched the door handle (all 4 doors) to open the door but no luck. Screen said "Key Not Recognized"
2. Pressed the "Open" button from remote key (Radio Frequency) but no luck to open the door
3. Tried with "Infra red" option in remote key by pressing "Open" button and pointing the remote key to IR reception on Driver door handle, but no luck to open
4. I was able to open the door with mechanical key, this caused the alarm off. Immediately I inserted the key into the ignition and the alarm stopped and I was able to start the engine
5. I noticed when I opened the door (at point 4), the side mirrors (both side) only opened half way (I setup an automatic open/close side mirror)
6. From AC screen, I selected #24 to check the alternator. Before I started the engine I have 11.9v, after I started the engine I have 14.1v
7. After I am driving around, I am able to lock/unlock door with infra red option in remote key (very close distance), but Keyless Go and Radio Frequency features still not working

I have 2 Keyless Go remote keys and have the same result/behavior.
The Keyless Go start engine button does not work, too.
The trunk open/close button only works after point #4 (manual only, not from remote key)

tusabes

Weak car battery

wlmteng

Thanks, tusabes.

That's what I thought, too. I visited 2 MB dealerships, one of them said the common problem is the PSE pump but the dealer required me to run star diagnostic ($175) to get the exact problem.

Can I setup another battery (like jump start from another car) just to test (Keyless Go or RF feature) if the weak battery is the root cause?

ibeforreal

Be VERY CAREFUL when you try to jump start your car because it can cause all kind of problems to the electronics. You would be better off taking your battery/car to one of the local auto parts store that will check it for free.

tusabes

As stated , jump with another battery can cause more electrical problems . Take out your battery and put a good one in. There's no shortcut .

Testing at an auto parts store will not work on a w220. Batteries strong enough to test good may still be too weak . A w220 is very very sensitive and needs a strong battery , an older one that will still be strong enough to start a car may still be too weak for all the w220 systems to operate properly

wlmteng

Thanks everyone! The problem is solved. It was a weak battery.

I replaced the battery with Die Hard Advanced Gold group size 49. To save the car settings, I followed the guide at this link .

Now all the issues are gone.