Please Help! My SmartKey only works after car has recently been running
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Please Help! My SmartKey only works after car has recently been running
Last week my SmartKey stopped working. Not a big deal *I thought* - just went and got new batteries, put them in, thought that would be it.
Wrong.
So I have to use the mechanical key to open the door - and endure the embarrassment as the alarm goes off - and at least the Smartkey then works to start the car.
Here's the twist though....
If/when I turn the car off, the SmartKey works - lock, unlock, lock, unlock. And if I get out & lock the doors and am not gone lone, the SmartKey works when I come back and try using it to unlock the doors. But if the doors are locked for more than an hour (i.e. while I'm at work, overnight, etc.) , when I try to use the SmartKey to unlock the doors - nothing. Back to the mechanical key.
This is driving me crazy! I'm praying someone has had this happen to them and can help me out....
Desperate in Florida
Wrong.
So I have to use the mechanical key to open the door - and endure the embarrassment as the alarm goes off - and at least the Smartkey then works to start the car.
Here's the twist though....
If/when I turn the car off, the SmartKey works - lock, unlock, lock, unlock. And if I get out & lock the doors and am not gone lone, the SmartKey works when I come back and try using it to unlock the doors. But if the doors are locked for more than an hour (i.e. while I'm at work, overnight, etc.) , when I try to use the SmartKey to unlock the doors - nothing. Back to the mechanical key.
This is driving me crazy! I'm praying someone has had this happen to them and can help me out....
Desperate in Florida
Last edited by europe4fun; Jul 8, 2006 at 09:36 PM. Reason: typo
Member
Joined: Jun 2005
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From: Santo Domingo
CLS55
MB cars are equipped with two batteries. The larger one for the raido, ac, lights, etc... while the smaller one is for the alarm system.
Check to make sure your smaller battery is charged or needs replacing.
Check to make sure your smaller battery is charged or needs replacing.
Senior Member
Joined: Mar 2006
Posts: 302
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From: Dublin, OH
05 ML350, 85 300D
Originally Posted by Redbud
MB cars are equipped with two batteries. The larger one for the raido, ac, lights, etc... while the smaller one is for the alarm system.
Check to make sure your smaller battery is charged or needs replacing.
Check to make sure your smaller battery is charged or needs replacing.
A- not all MBs have 2 batteries- primarily, it is the SBC cars
B- The alarm has it's own battery built into it.
C- the second battery is there to ensure the SBC brakes always have enough voltage and are used for:
1- SLs (230)- to start the car only
2- E-class(211) and CLS (219)- to act as a helper battery if the main battery's voltage falls too low
(won't get into Maybach and SLR-it's not important)
Now, onto the problem with the key- sounds like the key works fine, but the Can isn't waking up when it gets the signal. If you don't let the car go to sleep, everything is fine. The RF antenna gets the signal and passes it to a control module, and that module is supposed to wake up and wake the rest of the car up. Without knowing the year/model we are talking about- it's hard to say what module this is- but that would be my first place to look. Let me know and I'll look it up for you.
MBWorld Fanatic!
Joined: Nov 2001
Posts: 4,260
Likes: 6
From: Philadelphia area
2010 ML550, 2010 E350 4M, 1966 Corvette Convt C2
Originally Posted by MBTech21
Not sure where you heard that- but it's not true.
A- not all MBs have 2 batteries- primarily, it is the SBC cars
B- The alarm has it's own battery built into it.
C- the second battery is there to ensure the SBC brakes always have enough voltage and are used for:
1- SLs (230)- to start the car only
2- E-class(211) and CLS (219)- to act as a helper battery if the main battery's voltage falls too low
(won't get into Maybach and SLR-it's not important)
Now, onto the problem with the key- sounds like the key works fine, but the Can isn't waking up when it gets the signal. If you don't let the car go to sleep, everything is fine. The RF antenna gets the signal and passes it to a control module, and that module is supposed to wake up and wake the rest of the car up. Without knowing the year/model we are talking about- it's hard to say what module this is- but that would be my first place to look. Let me know and I'll look it up for you.
A- not all MBs have 2 batteries- primarily, it is the SBC cars
B- The alarm has it's own battery built into it.
C- the second battery is there to ensure the SBC brakes always have enough voltage and are used for:
1- SLs (230)- to start the car only
2- E-class(211) and CLS (219)- to act as a helper battery if the main battery's voltage falls too low
(won't get into Maybach and SLR-it's not important)
Now, onto the problem with the key- sounds like the key works fine, but the Can isn't waking up when it gets the signal. If you don't let the car go to sleep, everything is fine. The RF antenna gets the signal and passes it to a control module, and that module is supposed to wake up and wake the rest of the car up. Without knowing the year/model we are talking about- it's hard to say what module this is- but that would be my first place to look. Let me know and I'll look it up for you.
MBWorld Fanatic!
Joined: May 2003
Posts: 4,005
Likes: 106
From: Houston, TX
2015 E250D
some of the newer cars also have 2 batteries without SBC. As for the control module, it is probably your door control module. These are known to go bad in early C class cars which i presume is what you have.
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MBTech21, I have a 2003 C320. I appreciate your insight. Any further help you can offer would be greatly appreciated. Thanks-
europe4fun
p.s. sunman, seems we drive the same model. I **love** the way you have yours decked out. Wish mine had all those features!
europe4fun
p.s. sunman, seems we drive the same model. I **love** the way you have yours decked out. Wish mine had all those features!
Last edited by europe4fun; Jul 10, 2006 at 12:18 AM.
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Senior Member
Joined: Mar 2006
Posts: 302
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From: Dublin, OH
05 ML350, 85 300D
Originally Posted by sosh
Re the 2 battery situation, if what you say is correct, and I do not doubt it, Why and for what purpose does my W164 have 2 batteries??? No SBC brakes as my W211 has which I know has 2 batteries also.
The second battery on a 164 (both X and W), and the 251, and the 221 is to make sure the car goes into park, if main battery power fails. All these cars are equipped with the electronic shifter.
FYI...if that does happen, it won't take it out of park, it's towing time!!
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Senior Member
Joined: Mar 2006
Posts: 302
Likes: 0
From: Dublin, OH
05 ML350, 85 300D
Originally Posted by europe4fun
MBTech21, I have a 2003 C320. I appreciate your insight. Any further help you can offer would be greatly appreciated. Thanks-
europe4fun
p.s. sunman, seems we drive the same model. I **love** the way you have yours decked out. Wish mine had all those features!
europe4fun
p.s. sunman, seems we drive the same model. I **love** the way you have yours decked out. Wish mine had all those features!
I assume you are not using the IR reciever in the door (in which case it is wired to the door module), but the RF antenna in the rear glass, which is wired to the rear sam. Seems odd that one of these wouldn't wake up the car (have you tryed both ways?-I just can't see both failing at once)
