Keyless Go on '04 S600 fails when car is cold
To sum up, all three of our key fobs "are not recognized" or just do nothing sporadically. Sometimes it works, sometimes it doesn't. We can't even use the valet key because it will set the alarm off. The only constant I can find is when the car is very cold (today was 25f deg), like when sitting in our driveway overnight, it just will not respond. All keys, all brought out one at a time (it reminds me of presenting offerings to the car begging it to like us). Today I waited for the sun to hit the car for awhile and bazinga! Car opens up. Car starts.
Thoughts? Help? Do any of you know what I can guide my mechanic to? Or should I just go somewhere else because I am feeling he is less a mechanic and more of a computer error responder. FWIW, the folks i use are Mercedes dealers.
The mechanics at the dealership, couldn't find the problem last winter, or the winter previously. However, they drove the car into the warm garage to inspect it each time. Its never been a problem in the warmth, so far. The mechanics haven't been particularly good on other problems either! So we having tried them this winter.
The battery is 6 years old, but has never failed us. But don't know if its a factor as it starts with the key.
Sorry that I'm no help, but if it I find something, I'll post an update.
There is a specialty Mercedes repair shop in our town. Good reputation. I'll try him and advise him what you found. Once we get the car back, I'll post the lastest news for you.
Taking 8 days to find the problem is scary. Thanks for the tip. It should shorten the time to check out the car.
There is a specialty Mercedes repair shop in our town. Good reputation. I'll try him and advise him what you found. Once we get the car back, I'll post the lastest news for you.
Taking 8 days to find the problem is scary. Thanks for the tip. It should shorten the time to check out the car.
I do appreciate you all responding with your stories.
Thirdly, I have the same problem too on my 2004 S600. I always check the battery in the keyfob with a voltmeter and never find a problem there. I have two suspects: if the car has low battery voltage then it switches off all devices that are not essentail. Keyless go may be one of these. The other thought is that one of the fob buttons was pressed accidentally in my pocket and was less powerful at that moment.
Neither theory is confirmed.
Can you check the following and report back to me? When you touch the door handle, please look a the key. Does the LED light up as if you had pressed a button on the key? If the LED lights up on mine then all is well.
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The temperature has warmed up somewhat. Last night it was approximately 5 – 10 F. I tried the key fob with the old battery, pressed the driver’s door button, and the red light on the key fob lit up! I decided to try to start the car by pressing the button on the shifter, and the car started! I was so surprised that I didn’t bother to try the key fob in the ignition.
I can’t even guess at what was originally going on with the key fob. The other key fob with the new battery was left in the house away from the car. I suppose that it’s possible that the car battery was low, but with the really cold temperatures that we had previously, I would have suspected that the car wouldn’t start with either of the key fobs. But the car battery is 7 years old!
I’ll continue to use the key fob with the old battery and report on what happens next.
Richard Arnold
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As I mentioned in an earlier posting, this problem used to be a winter issue that got worse each year. Its confusing to understand how the batteries could be an increasing problem each winter, but take so many years without the battery being completely 'dead'.
Richard Arnold



