LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400
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Key fob not working after dead battery... 98 LS400

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Old 04-25-14, 05:20 PM
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ma61
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Default Key fob not working after dead battery... 98 LS400

Took my 98 LS400 out of storage the other day. Apparently I forgot to disconnect the battery so it was flat when I went to get it.

Jumped it, and it started fine.

But, now the key fob will not lock or unlock.

I searched but couldn't seem to find any answers, does anyone know what the reason for this is and what I have to do?

The LED on the fob still lights so I don't see how it would be a dead battery in the key.
Old 04-25-14, 05:48 PM
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sha4000
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Easy way to find out is to just put a new battery in it.
Old 04-25-14, 06:50 PM
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check keyfob battery
then
check all fuses.
Old 06-03-14, 07:40 AM
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billydpowe
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PD need some help.. my 99 fob will lock every time, will not unlock EXCEPT maybe once out of 30 times. new battery installed, no change, went to reprogram the fob and lock/unlock button on the door is the same way... it always locks the doors, but rarely will unlock them.. AND then all of a sudden the inside switch works and the fob worked ONE TIME. also when the fob is not working, it will not open the trunk either..
any suggestions??
Old 06-03-14, 10:21 AM
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RA40
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Worn out? I've acquired a couple over the years from that auction site that arrived with dead buttons/functions.
Old 06-03-14, 10:26 AM
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billydpowe
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Originally Posted by RA40
Worn out? I've acquired a couple over the years from that auction site that arrived with dead buttons/functions.
dead buttons? yes, maybe but why my door lock switch working in unison with FOB. ??
Old 06-05-14, 09:41 AM
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ma61
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Originally Posted by ma61
Took my 98 LS400 out of storage the other day. Apparently I forgot to disconnect the battery so it was flat when I went to get it.

Jumped it, and it started fine.

But, now the key fob will not lock or unlock.

I searched but couldn't seem to find any answers, does anyone know what the reason for this is and what I have to do?

The LED on the fob still lights so I don't see how it would be a dead battery in the key.
Originally Posted by sha4000
Easy way to find out is to just put a new battery in it.
Originally Posted by PureDrifter
check keyfob battery
then
check all fuses.

Forgot to update the thread, it was the fob battery... derp.
Old 06-05-14, 12:22 PM
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RA40
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Originally Posted by billydpowe
dead buttons? yes, maybe but why my door lock switch working in unison with FOB. ??
That may be a question to direct towards Yamae.
Old 06-05-14, 02:03 PM
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Dubbayoo
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My Mazda 626 had a programming sequence.

Open driver's door and leave open.
Insert the key into the switch and turn to ON and OFF position three times. Note: turn to the ON and not the ACC position!
Take key out of the ignition.
Press the driver's door ajar push-button three times. This button is located on the center pillar between the driver's door and the rear door. It is on the bottom part of the pillar and is pointing out.
Press any button on the first remote. After several seconds, the dashboard buzzer will beep.
Repeat step #5 for all the other remotes.
When you are done, shut the door. The car will beep several times.

Does Lexus have anything like this?
Old 06-05-14, 04:31 PM
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Yamae
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Originally Posted by RA40
That may be a question to direct towards Yamae.
The problem only happens at non-lock button may be caused by the increased resistance or the chattering of the contacts. Aged contacts tend to have this type of problem. It can be confirmed obseving the resistance or the waveform but this needs to open the plastic box and this will loose the airtightness.
Old 06-05-14, 05:14 PM
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RA40
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I suppose that is to be expected on these aging-used items. I take for granted "solid state" electronics though over time they do degrade from spec. On top of this we have mechanical switches that trigger the remote functions and those will wear.

Can something like this be related to the multiplex communication system or does it remain within the door-security ECU system?
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