SC- 1st Gen (1992-2000)

Has the well known "battery drainage" on the SC been discovered?

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Old 07-01-13, 12:38 PM
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SC400slide
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Default Has the well known "battery drainage" on the SC been discovered?

Most SC owners are aware that if they leave their SC parked for 2-3 weeks, maybe even 1 week, the battery drains and the car will not have enough cranking amps to start the engine. Has this issue ever been solved once and for all? Ali was looking for the cause awhile back and figured out that
1.Might be the monster power seat motors (that you can move without the key in the ignition) just like the Mercedes sedans
2.It's not the trunk CD changer light (that would take a while anyways. Ali recorded with his phone and put it inside the trunk to confirm that the CD changer light does go off.)

If anyone has any ideas, maybe we can figure this thing out.

I know this is random, but I was wondering if it could be the way the diode pack was made in the alternator. Just FYI,
it's function is to allow electrical current to flow in one direction only, a symptom of a bad diode tree will be a battery that drains while parked, as the alternator is connected to live power at all times a bad diode will allow power to reverse direction to ground, thus dead battery
Just a wild guess, and to fix, would take redoing them.

Ali also suggested that if you're tired of coming to the SC and there is no power, you might consider getting a 12 volt circuit breaker. When the SC is in storage, just flip the switch and save your battery. That is a redneck fix though, sort of like putting seat covers on ripped leather seats. (which bother me crazy in a Lexus BTW)

Would love to hear from personal experience.
Old 07-01-13, 12:48 PM
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chiken
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I found that my trunk leaks just a little on my CD changer and amp just below. The amp has corrosion and my parasitic draw leaves when I unplug just the amp. I'll let you know if that was for sure my problem once I track down a decently priced amp.
Old 07-01-13, 01:49 PM
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Ali SC3
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Mine only seems to drain in the winter... when its warm out I have no draining issues at all.
most amps will cause some drain I had all my issues with no amps in but we could all have different issues there is a lot of old electronics in our cars. I'm hoping I have more time next winter to track it down finally.
Old 07-01-13, 01:52 PM
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Originally Posted by SC400slide
Most SC owners are aware that if they leave their SC parked for 2-3 weeks, maybe even 1 week, the battery drains and the car will not have enough cranking amps to start the engine. Has this issue ever been solved once and for all?
It says very clearly in your owners manual why the battery drains. Look under the security section. I don't remember the wording or I'd say.
Old 07-01-13, 03:07 PM
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^^ more info on this please??? i thought it was just me and my damn car was cursed after my swap. this is very dumb, if i have an alarm system, whats the point if i have to disconnect my battery to keep it from draining??

i don't have any amps or stock seats and this still happens.
Old 07-01-13, 03:41 PM
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Originally Posted by O. L. T.
It says very clearly in your owners manual why the battery drains. Look under the security section. I don't remember the wording or I'd say.
Security system drains the battery? The manual doesn't explain that, at least from what I read. http://drivers.lexus.com/t3Portal/do...5U/pdf/1-7.pdf
Old 07-01-13, 03:55 PM
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Booty, effing booty!!!!
Old 07-01-13, 04:36 PM
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O. L. T.
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Originally Posted by SC400slide
Security system drains the battery? The manual doesn't explain that, at least from what I read. http://drivers.lexus.com/t3Portal/do...5U/pdf/1-7.pdf
Yeah it's related to the keyless switch under the dash. I forget how. Been YEARS since I saw it. Says specifically if you plan on leaving your Lexus parked for more than a few days hook it to a battery tender because "insert dialog here".
Old 07-01-13, 05:22 PM
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That switch is off on mine and mine still drains, though, it is part of the drain for others.
Old 07-01-13, 05:37 PM
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Teal Sc400
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Originally Posted by O. L. T.
Yeah it's related to the keyless switch under the dash. I forget how. Been YEARS since I saw it. Says specifically if you plan on leaving your Lexus parked for more than a few days hook it to a battery tender because "insert dialog here".
Your statement Is correct and can be found in the older Sc owners manual. I have a '92 owners manual and on page 11 it has a picture of the main switch on the dashboard (to the right side of the trunk lid opener) along with a notice of turning the main switch to OFF to prevent draining of the battery, when vechile is not used for long period of time.
The problem is the main switch button is not offered on the later model Sc's at least not on my '95.
Old 07-01-13, 05:39 PM
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Too many computers in our cars.
Old 07-01-13, 05:45 PM
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Originally Posted by Luxor
Too many computers in our cars.
Or a Gremlin
Old 07-01-13, 06:46 PM
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so do any other modern or old, aftermarket or oem car alarm system drain the battery??
Old 07-01-13, 08:57 PM
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I have a battery tender on my sc300.
Old 07-01-13, 10:24 PM
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I have a '96, and the owners manual does reference a possible dead battery if you leave the headlight switch in the auto position. It suggests if the car is to be parked for longer then like a week, to turn the switch to the off position.

It might be worth it to measure voltage draw, and then start pulling fuses till the circuit is isolated, might be a relay stuck on.


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