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  #1  
Old 07-04-2021, 11:58 AM
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Code A2CD

I have this code A2CD means Undervoltage.

My Alternator shows 14.4V

My battery is 4 years old.

Should I replace the battery?

Let me know what you guys think the problem is.
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  #2  
Old 07-04-2021, 12:51 PM
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You need to monitor the voltage over time. A spot test from the alternator doesn't mean much.

Usually when you get an under voltage situation it's just when you lift throttle to coast to a stop.
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Old 07-06-2021, 01:23 PM
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what are the circumstances?

One code you just found?


Shows up every day, even after resetting...and even when driving 50+ miles a day with a fully charged battery??
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Old 07-06-2021, 03:10 PM
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what are the circumstances?

One code you just found?


Shows up every day, even after resetting...and even when driving 50+ miles a day with a fully charged battery??
Well, I have this issue where my key fobs flip flop between working and not working the next day, and then 4 -5 days a week later they work again.

Kind of pissed me off very much. I've been researching high and low for this unique issue, so I did a deep scan and that is what I found which I can not reset. I checked test #9 and got about 11.9V reading for the battery.

So, I wonder because my battery is no longer take charge to the max and because it is reading 11.9V the software thinks it should cut off its limps so the heart can survive and that is why my key fobs are intermittent working.

What do you think? Thanks for your interest.
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Old 07-06-2021, 04:21 PM
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Low main battery can cause you to lose sync on the fob. Usually however intermittent working means bad solder joints in the fob.


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Old 07-06-2021, 06:04 PM
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Low main battery can cause you to lose sync on the fob. Usually however intermittent working means bad solder joints in the fob.


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What chance do both key fobs go out and back in at the same time for 4-5 iterations now due to cold solder joint?

No chance, but thank you though.
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Old 07-06-2021, 06:38 PM
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Code A2CD

Both mine did. I reflowed and fixed them both. That said they were older. The thing is if they lose sync from low main battery they won't re-sync on their own so I'm thinking maybe an antenna receiving problem. (since if I'm reading you correctly they work on and off).

When mine (both) had bad solder joints they would usually work immediately after locking the car or after open/close the hatch as if at that time the car raises the gain on the receiving antenna.

I can't remember as It was five years ago but I think if I locked the car with the key blade I could unlock with the fob for a minute or so but if I went to the house and back five minutes later no go. Then I would unlock with the key blade and for a minute again I could lock/unlock with the fob as much as I wanted for the next minute or two.

Symptoms sound familiar? That's why I mentioned. From reading many dozens of threads of keyfob not behaving but sometimes working 5% battery 90% solder joints 5% something else.
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Old 07-06-2021, 06:44 PM
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Both mine did. I reflowed and fixed them both. That said they were older. The thing is if they lose sync from low main battery they won't re-sync on their own so I'm thinking maybe an antenna receiving problem. (since if I'm reading you correctly they work on and off).

When mine (both) had bad solder joints they would usually work immediately after locking the car or after open/close the hatch as if at that time the car raises the gain on the receiving antenna.

I can't remember as It was five years ago but I think if I locked the car with the key blade I could unlock with the fob for a minute or so but if I went to the house and back five minutes later no go. Then I would unlock with the key blade and for a minute again I could lock/unlock with the fob as much as I wanted for the next minute or two.

Symptoms sound familiar? That's why I mentioned. From reading many dozens of threads of keyfob not behaving but sometimes working 5% battery 90% solder joints 5% something else.
Both my keyfobs will work for a day or two then not for a few days up to a week. Then started to work again.
I replaced the main battery and one key fob battery don't make any difference.
I hate to go change the antennae without confirmation though.
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Old 07-06-2021, 10:05 PM
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I would hope if antenna related it's a bad connector or damaged wire. Common fault with e53 is the rear hatch wiring loom will have a wire break. It can re-connect when it wants and that would exhibit the symptoms you describe.
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