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  #1  
Old 05-04-2012, 08:04 PM
Ken Ken is offline
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Remote Key Fob Battery Warning - How Does It Work?

The Owner's Manual for my 2010 Cobalt says that a warning notice will appear on my dashboard if the battery in my remote key fob is near the need for replacement. I would like to know how that is done.

Is the strength of the signal emitted by the key fob sensed in some way and a low signal triggers the warning?
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  #2  
Old 05-04-2012, 08:13 PM
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Never heard of that, but if that did exist it would not be very smart as it would result in more battery use to send that signal, resulting in that almost dead battery to get drained even faster.

I would imagine the remote has a driver chip that checks the voltage and if it does not meet a certain threshold, it will send the signal to the car to let you know. However, I'm just speculating.
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Old 05-04-2012, 09:05 PM
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Every time you press a button on your key FOB, your remote sends 3 signals. First is a burst to wake-up your car, actually it will wake-up all GMs around your car. Second it sends a car ID pulse train. Thirdly it sends it's command ex: "Door Unlock". Okay remember the first one the burst. Well this is produced by a VCO which stands for Voltage Controlled Oscillator. The higher the voltage the higher the frequency and vice versa. What the car BCM measures is not the voltage per say but the frequency sent by the remote. When the frequency gets below a set threshole the BCM sets an alarm.

Any questions?
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Old 05-04-2012, 09:26 PM
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Originally Posted by Coby7 View Post
Every time you press a button on your key FOB, your remote sends 3 signals. First is a burst to wake-up your car, actually it will wake-up all GMs around your car. Second it sends a car ID pulse train. Thirdly it sends it's command ex: "Door Unlock". Okay remember the first one the burst. Well this is produced by a VCO which stands for Voltage Controlled Oscillator. The higher the voltage the higher the frequency and vice versa. What the car BCM measures is not the voltage per say but the frequency sent by the remote. When the frequency gets below a set threshole the BCM sets an alarm.

Any questions?
yea i have one...how do you know so much about cobalts?!?!?!?! i wish i had all this knowledge i would feel so cool all the time

also this is not sarcasm incase you were taking it that way 100% serious
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Old 05-04-2012, 09:26 PM
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Question:

So the low battery low signal is only sent when you lock/unlock your car?
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Old 05-04-2012, 09:28 PM
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Quote:
Originally Posted by johnccc View Post
Question:

So the low battery low signal is only sent when you lock/unlock your car?
sounds like anytime you hit a button on the fob
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Old 05-04-2012, 09:30 PM
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Question:

So the low battery low signal is only sent when you lock/unlock your car?
i thought it was sending the battery strength signal everytime you hit a button and when its finally low enough it triggers the alert or whatever on the DIC
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Old 05-04-2012, 09:37 PM
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It doesn't send a low battery signal. It's the BCM that deduces the battery is low because of the burst frequency. And yes any button that is pressed sends burst,IDcode and command.

---------- Post added at 12:37 AM ---------- Previous post was at 12:34 AM ----------

Quote:
Originally Posted by Rriggs92 View Post
yea i have one...how do you know so much about cobalts?!?!?!?! i wish i had all this knowledge i would feel so cool all the time

also this is not sarcasm incase you were taking it that way 100% serious
LOL, I'm not that sensitive. And I forgot more than I remember, go figure. You should see the questions asked on the Mitsubishi and Husqvarna forums.

Plus I like to read rather than watch TV.
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Old 05-04-2012, 09:46 PM
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Originally Posted by Coby7 View Post
It doesn't send a low battery signal. It's the BCM that deduces the battery is low because of the burst frequency. And yes any button that is pressed sends burst,IDcode and command.

---------- Post added at 12:37 AM ---------- Previous post was at 12:34 AM ----------



LOL, I'm not that sensitive. And I forgot more than I remember, go figure. You should see the questions asked on the Mitsubishi and Husqvarna forums.

Plus I like to read rather than watch TV.

Makes Perfect sense to me, as an additional battery sensor would just use more of whats left, kinda like when you charge a cell phone and it stays illuminated the whole time, cant help in charging time.

But still, even though it would take a long time, it would reduce the life of the battery, just a little bit, but at the same time it would alert you at the same time, cons and pros are probably going to break even.
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  #10  
Old 05-04-2012, 09:52 PM
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By doing it this way it meant they didn't have to change de design of the actual remote. Work with what you got type of deal.
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