michael_ghost32
Lexus ES Battery Alarm
Summary of the thread
A 2020 Lexus ES is experiencing a battery alarm issue, with the alarm system not functioning. The likely cause is a discharged auxiliary battery, which can affect the alarm system when the voltage drops too low. Checking the battery with a multimeter for a voltage below 12.6V can confirm the issue. Replacing the battery and clearing error codes resolved the problem, restoring the alarm system's functionality.
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4 comment(s)
michael_ghost32 (community.author)
I don't think it has ever been replaced. Where exactly is the auxiliary battery located in the ES? And what voltage am I looking for on the multimeter?
willibaumann40
On your ES, the auxiliary battery is usually near the main battery. You're looking for a voltage reading below 12.6V. A weakened battery will trigger the alarm system failure. It's probably best to get it checked by a shop, since you'll need to recode the system, too.
michael_ghost32 (community.author)
Thanks a ton for the help! Turns out the battery was knackered after all. Ended up costing me 330€ to have a shop replace it and clear the error codes, but at least the car alarm is working again!
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LEXUS
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ES
willibaumann40
Sounds like a discharged auxiliary battery is the most likely suspect, especially given the age of the car. Has the battery ever been replaced? These Lexus systems can be finicky when the voltage drops too low. A multimeter check could confirm your suspicions.