2012 S550 Keyless Go
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Joined: Jan 2018
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S-550
2012 S550 Keyless Go
I have a 2012 S550 that will not recognize the Keyless Go. I have two Key fobs and had new batteries put in both to be sure. One day the unlock function and push button just stopped working. Pulled the button and used the fob to start the car , no problem. Fob also unlocks and locks doors manually no problem
Checked all the fuses under the hood and in side of dash on drivers side, all good. Battery under hood is 21.2 VDC
Any ideas?
Thnaks
Checked all the fuses under the hood and in side of dash on drivers side, all good. Battery under hood is 21.2 VDC
Any ideas?
Thnaks
Super Member
Joined: Feb 2007
Posts: 809
Likes: 74
From: Dallas, TX
2008 E63 wagon (1 of 62)
Are they both the original keys or have they been replaced? I'm assuming they both worked as keyless go previous to the issue. Also, assuming that is supposed to be 12.2 VDC for the battery under the hood. Once in a great while with the keyless go system, you may have to remove the Start/Stop button from the EIS and insert the key to start it. After that everything should work as normal again. Sometimes the vehicle may have an undervoltage issue with cold weather or after sitting for an extended period. If this happens, this basically teaches the key back into the vehicle system and everything should be okay.
Is the vehicle still not operating properly via keyless go to start or the keyless lock/unlock on the exterior door handle? If this is happening with both keys, then you may have an issue with one of the antennas around the car. Try from a passenger door or even the trunk lid and see if they work via keyless operation.
Is the vehicle still not operating properly via keyless go to start or the keyless lock/unlock on the exterior door handle? If this is happening with both keys, then you may have an issue with one of the antennas around the car. Try from a passenger door or even the trunk lid and see if they work via keyless operation.
Thread Starter
Newbie
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S-550
Thanks for fast response. Yes, both keys are original. I have removed the start button and been driving the car with the key in the ignition. I live in Florida so cold weather is not the issue. My kids said they heard the alarm squeak the night before it happened? I don't know if that is related or just dumb luck.
The GO function to unlock the doors doesn't work. The fob does unlock doors and trunk manually.
The GO function to unlock the doors doesn't work. The fob does unlock doors and trunk manually.
Super Member
Joined: Feb 2007
Posts: 809
Likes: 74
From: Dallas, TX
2008 E63 wagon (1 of 62)
But, have you tried unlocking the passenger side door with the key in your pocket using only your hand to unlock/lock with the button on the handle? There s more than one antenna for the keyless entry system and if one of those has failed, the rest should still be working. If nothing is working, except manual use of the key buttons, you may be looking at key replacement. Generally both keys don't go out at the same time unless you ran them both through the clothes washer at the same time. Before blaming it on keys though, find someone who can hook it up to a Star system and check actual values of the keyless go systems.
Thread Starter
Newbie
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S-550
I just tried the FOB in pocket in passenger side, no go.
Also, both FOBs totally function from far away and have new batteries. The spare FOB has been in the little baggy from the dealer since I got the car, its brand new. The day it happened I tried both FOBs and they both function in every way except hands free unlock and push button start. So I replaced the batteries in both, no change.
Also, both FOBs totally function from far away and have new batteries. The spare FOB has been in the little baggy from the dealer since I got the car, its brand new. The day it happened I tried both FOBs and they both function in every way except hands free unlock and push button start. So I replaced the batteries in both, no change.
Super Member
Joined: Feb 2007
Posts: 809
Likes: 74
From: Dallas, TX
2008 E63 wagon (1 of 62)
Well sad to say this, but you need to find someone to do further diagnosis or take it to a stealership you trust and let them know what you have already tried. Starting out with the basics like you have tried, can save you in most situations.
