Hi Club Lexus,
I Have been facing issues with my 2008 LS460 and unable to resolve this parasitic battery drain.
Initially I hadn't started my car for about a week and resulted in a dead battery. Assuming age of the battery had it replaced. In about a months time, started getting ABS Indicators and one fine day vehicle doesn't unlock and dashboard doesn't light up. Possibly battery dead. Jump started the car and mechanic stated faulty display causing battery drain. Replaced the display. Battery replaced under warranty. Mechanic stated while handing the car that there is possible weak ABS issue as well. 3 days down, same issue, battery drained to the point that car doesn't unlock and dashboard doesn't light up. Towed the car to the mechanics and ABS replaced. Car checked and no issues of battery drain. This was 3 days back. Today, car unlocks, dashboard lights up but doesn't take ignition. Possibly the battery still has limited power available. Indicators show the following - Battery Low, Parking brake not available, check SRS Airbag system.
Im a complete rookie with such things an would like to understand what could be the possible issues?

 

https://www.clublexus.com/forums/ls-...nius-10-a.html

 

I think several of us are facing the same root cause. I initially thought I had a bad battery, but like you, after replacing it the problem has continued. Your mechanic likely stated there's an ABS issue because the control unit monitors voltage and charges its own backup power supply for the brake-by-wire system. This throws code C1241; I've had it on my own car when the problem is at its worst. I appreciate that jdanielca's solution addresses the issue of not starting, but I'd like to figure out what's actually causing the voltage drain.

In my case, I've noticed that the headlights have been staying on indefinitely after locking the car. I don't mean the normal delayed auto-off function; I've even tried disabling that feature completely via Techstream and they still remain on. Unfortunately, the FSM doesn't provide much detail on troubleshooting this issue. It provides exactly one possible cause under the symptoms table: main body ECU. This is the control unit attached to the fuse block by the driver's feet. Also unfortunately, there's no troubleshooting process provided.

I also wonder if it might be caused by excessive CAN chatter or modules not "sleeping". Under normal conditions, the various control modules throughout the car should enter low-power states after the car is switched off and/or locked. I might try monitoring the network while locking the car, but I don't know if the LS freaks out with a device attached to the OBD port while locked. I know newer BMW cars specifically have an issue with this.

 

Maybe some help here for headlights staying on:
https://www.clublexus.com/forums/ls-...mb-switch.html

 

Much thanks; I completely missed this! Has Lexus ever acknowledged this by way of a SB, or is this detective work by yourself?

 

Glad you found the information useful. And thanks for the acknowledgment.

We have discussed the doorjamb switch issue extensively in this forum. Be sure to read all of this thread if you are having problems with your headlights staying on: https://www.clublexus.com/forums/ls-...rning-off.html

As far as I know Lexus has never provided any help for this problem. Probably not enough money in it to get dealership interest - they like to replace batteries.

Other than an occasional acknowledgment I don't get anything other than the pleasure of helping people. Thanks to ClubLexus.com for providing the site for these discussions.

Merry Christmas, everybody.

 

So I read on a certain solution on a couple of threads here and again on Reddit. Said to switch off your car for about 20mins to ensure powering down of the car to normal minimal voltage use. Connect a multimeter and check your power usage to identify a drop in voltage while removing out fuses from the fuse box one after other. For my specific car, I found a specific bad relay that could have been causing the drain. However, previous drain issue popped up after 4 to 5 days of normal car usage. Today is the 3rd day of use. Insha Allah, I hope the root of the problem is the one that is found and should not repeat. Will post and update after I'm sure of this resolving the issue.

 

👍yes, that's basically the process to measure standby voltage. Turn the car off, then turn it on without starting the hybrid system, turn the lights on briefly, then turn it all off again and wait 20 minutes. The idea is to eliminate the "surface charge" phenomenon. Hopefully you've nailed your cause!

 

I have issue with battery draining. I went to replace it with new battery but I was advised my battery was fine. My headlamps are normally on when the ignition is on, but recently the lights are not coming on (which is a first). It was at the same time my battery drained. Both bulbs have been replaced a few months ago. From what I hear it could be a number of reasons. I heard many cases of either drivers or passenger lights goes, which happened to me once. I replaced the 2 and that solved the problem. Now I have a new issue to deal with...

Any feedback would be great.

 

I have the same issue with my 2009 but it's the high beam that are acting up whenever I start the car everything is fine but if I turn on the high beam (or even only the DRL) they turn off almost imediately (about 10 seconds) today with a friend I tested the battery, starter and alternator with a tester and everything was fine but after I turned off the the engine to scan the codes but the voltage dropped from 13V to 6V in less than a minute. That is an insanely quick drainage

 

I had a battery drain issue with mine. Luckily for me I have the knowledge how to test circuits and was able to determine the parasitic drain. The cause was the lamp in the inside of the trunk lid. I removed the bulb and battery drain issue went away. Easy way to test is to lower the trunk pass-through. Open and close the trunk then go inside the car and look into the trunk to see if the lamp is still on after it closes.

 

Either your battery has failed or something in your car is on fire

 

When I first bought my car, the Lexus maintainence website showed that the battery was replaced several time. I had an issue with brake error lights where the abs module and accumulator were replaced without a fix. I finally took it to another Lexus dealer about 200 miles away that diagnosd it to a control box on the drivers side engine compartment with integrated relays. The issue was fixed after it was replaced, and no dead or batteries replaced since then. The relays are under the fuses and potted in a clear material.