LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400

Keyless entry stopped working after dead battery

Old 10-10-13, 09:42 PM
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rosegold
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I've searched and searched and can't find anything that is relevant to what happened to me.

So I was at school and I went to open my car with the remote and nothing happened. I thought my remote battery died but the light blinked every time I pressed the button. But the car would not respond. I opened the trunk manually and put my backpack inside. Then I went to open the driver door manually. When I got inside the car I noticed there was No power. The overhead light was extremely dim. I got a jump start from my friend and realized my hazard lights were on, which obviously caused my battery to die. I got home and turned off the car and went to lock the car using the remote and nothing. Held the panic button down and nothing. I held the trunk button down and nothing.

Basically my question is would the battery dying and my opening the trunk manually then the driver door manually affect the remote from communicating with the car?

The car is a 1999 ls400.

I also noticed that whenever I would lock the car with the remote the security light would blink. Now that I lock the car from the inside since the remote won't work the security light is just steadily on and doesn't blink.

Last edited by rosegold; 10-10-13 at 09:47 PM.
Old 10-11-13, 01:22 AM
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LScowboyLS
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the remote unlock system will not work correctly without a good battery at proper voltage, please take a voltmeter and test across your battery with car off, you should have at lest 12.5 volts DC (VDC or DCV on meter)

if the reading is less than 12.5V, then you need to recharge battery (remove battery from car first) or else buy a new battery

if the battery is 4 or more years old, just replace it, it is worn out!

with the new or charged battery installed, take another measurement and make sure you have at least these voltages or higher:

12.5 with car off
13.6 with car at idle
14.0 with car running at 2000 rpm

if either of those last two is low, you may also need an alternator
Old 10-11-13, 02:28 AM
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Yamae
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A fully discharged car battery increases the internal resistance and the remaining life is extremely shortened. As LScowboyLS wrore, if the battery is 4 or more years old, just replace it.

You didn't write how long the hazard lights were on nor how many miles you drove the car from your school to your home, there's a fact that you couldn't lock the car using the remote after arriving home. This simply means that the battery was not charged but the engine was running. Judging from the situation, the highest possibility is the dead battery..
Old 10-11-13, 10:31 AM
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rosegold
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Originally Posted by Yamae
A fully discharged car battery increases the internal resistance and the remaining life is extremely shortened. As LScowboyLS wrore, if the battery is 4 or more years old, just replace it.

You didn't write how long the hazard lights were on nor how many miles you drove the car from your school to your home, there's a fact that you couldn't lock the car using the remote after arriving home. This simply means that the battery was not charged but the engine was running. Judging from the situation, the highest possibility is the dead battery..
I'm definitely replacing the battery as I am sure it is note than four years old. I hope it resolves my issue.

To address how the latter part of your response the lights were on for about 9 hours while I was in class. I also drove the car about 20 minutes.

Now this morning I tried again to unlock the car via remote and No success. I opened the car manually and the car started right up with No hesitations. And I drove to school which is another 20 minutes. But still No luck. The battery should have charged to some extent. But as LScowboyLS stated the voltages must be very low.
Old 10-11-13, 10:39 AM
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LScowboyLS
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did you also replace the battery in the remote itself, and did you make sure to use the CORRECT battery size? - and did you get this coin type battery from a high turnover source such as Wal-Mart so it will be fresh? - some of the remotes even require two batteries stacked.
Old 10-11-13, 11:54 AM
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deanshark
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Originally Posted by Yamae
A fully discharged car battery increases the internal resistance and the remaining life is extremely shortened. As LScowboyLS wrore, if the battery is 4 or more years old, just replace it.
I must be one lucky guy. The battery in my car was purchased by previous owner in 2006 and when my alternator wasn't working a few years back I used to drive on just the battery. When it went dead and the car shut off, I just changed the battery with a good one, and did it all over again. I would charge one battery at night inside. I drove like that, switching batteries, for about 3 months till I changed the alt. (I was just lazy at that time) The battery I have in it now (7 year old Duralast) must have been fully drained at least 60-70 times.

Change a 4 year old battery???......Not me. Only when I need to. Like I said, I'm one of the lucky ones.
Old 10-11-13, 12:24 PM
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Originally Posted by deanshark
Change a 4 year old battery???......Not me. Only when I need to. Like I said, I'm one of the lucky ones.
Automobile 12V lead-acid batteries have a typical reliable lifespan of 4 years, and yes, they sometimes can last longer, but since you know it could go out anytime after that 4 years, and you are going to have to get one anyway, why not be proactive?

Batteries can often fail at the most inopportune place or time. What if you just happen to be in the wrong neighborhood when it fails? - What if you ended up missing the wedding, the funeral, the hot date, the anniversary dinner, the important job interview, or the non-refundable flight? - what about an emergency? - How much is a small amount of savings really worth?

I am more frugal than most people, but driving around on an ancient battery is just dumb, there is no way to sugar-coat it!
Old 10-11-13, 12:39 PM
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Dean you must have a well made quality battery. Some of the past ones were quite robust to handle deep discharges. The ones I've bought for the Lex go south in the 4-5 year mark and some at 3 years. The best I had was an Exide "Nascar", about 20+ years ago. Lasted 7 years and had two really deep discharge cycles on it.

As for the OP's remote issue, that baffles me. The security system shouldn't drop the stored codes on a dead battery. When I disconnect the battery whe storing the car while away, hooking it back up is a non-event. Other than losing the radio, seat and trip mileage memories.

As Cowboy mentioned, a fresh battery into the remote.
Old 10-11-13, 05:47 PM
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deanshark
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Originally Posted by LScowboyLS
Automobile 12V lead-acid batteries have a typical reliable lifespan of 4 years, and yes, they sometimes can last longer, but since you know it could go out anytime after that 4 years, and you are going to have to get one anyway, why not be proactive?

Batteries can often fail at the most inopportune place or time. What if you just happen to be in the wrong neighborhood when it fails? - What if you ended up missing the wedding, the funeral, the hot date, the anniversary dinner, the important job interview, or the non-refundable flight? - what about an emergency? - How much is a small amount of savings really worth?

I am more frugal than most people, but driving around on an ancient battery is just dumb, there is no way to sugar-coat it!
I understand exactly what you're saying, ya never know. But, other then my tools and jack, I keep a fully charged battery in the trunk. I charge that one every few months just to make sure. Out of the 35 years I've been driving I have only bought 2 new and 2 used batteries. I have had some damn good luck with batteries. (No doubt) But yes, I know that is very unusual.
Old 10-13-13, 03:54 PM
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rosegold
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Just to update, the keyless entry system randomly started working again. My assumption is that the battery finally reached a level of charge to finally get the system to work again. Regardless, I will be changing the battery just as a precaution. As Cowboy stated the last things you want is the battery to die at the most inopportune moment and be S.O.L.

Thanks for the input guys.
Old 10-13-13, 05:45 PM
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LScowboyLS
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well I hope you replace both the battery in the car, and the battery in the remote fob!
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