fuddyduddy

I have now had the dead battery twice in the last four months. It's at the dealer now, I'll keep you posted about the solution.

bclexus

If the problem is not just pure bad luck with two defective batteries in four month's time it sounds like you may have a parasitic drain on the car's battery. This is what the problem was with a number of Lexus vehicles 5-6 years ago. It's my understanding the problem could raise its head at any time, including many years after the vehicle was first put into service. Also, the problem could go away and cease being a problem. The problem was difficult to confirm because a typical parasitic drain test would not always find it. From what I recall hearing there is one particular ECU computer unit that had a component (resistor, capacitor, diode, etc.) or a solder land on its printed circuit board that could have a tendency to cause a parasitic drain condition, which can discharge a vehicle's battery. Maybe it was affected by heat or humidity, but there was little certainty in most cases of being sure what the culprit was. I think at one point Lexus issued a bulletin and started replacing the ECU units more often.

Good luck with it. Let us know what the dealer finds...

fuddyduddy

Thanks, they are running the parasitic drain test and am waiting to hear back results. Preliminarily they said that they found some parasitic drain but had not yet located the culprit.

bclexus

Therein lies the problem that so many owners (and Lexus) had when this problem raised its ugly head years ago. It seemed the parasitic drain test was not always (rarely was) conclusive in determining exactly where the parasitic drain was located. Then, it was as-if the parasitic drain would magically heal itself for extended periods of time, where the dealer could not find a problem and would charge the customer's [drained] battery and send them on their way - all to have the same customer return a few days, or weeks or months later with the same problem.

You have one thing in your favor to hopefully have a positive outcome - they have at least acknowledged that they've found a parasitic drain. With their 'process of elimination' troubleshooting method they should be able to locate the culprit down to either a single load remaining On, or a single circuit drawing current due to say a high-resistance leak to ground, or inside one of the many computer units (e.g. PCM, ECM, ECU, TCM, TCU, etc.). I suspect they'll likely determine that the parasitic drain is caused by a current drain from within one of the computer units and replace it with a new unit. That would be what I would hope for.

fuddyduddy

They ended up replacing the gateway ECU. Not a horribly expensive part at the dealer - only $125 for the part plus labor. They waived the labor in lieu of the parasitic draw test labor. Now hopefully this works, only time will tell.

bclexus

Excellent! Thanks for letting us know what they found, and what they did...along with the price.

They aren't going to replace a part just on a hunch, so I'd say that was the culprit and should take care of the problem.

charley95

My original battery died saturday on my 14 RX in the garage. I didn't even mess with it and went to Toyota and replaced it. 15 minutes and $110 and done. It fits well and was a breeze to remove/replace. Glad it died at home.

PoopsMcGee

SOLVED (for me). I have a 2007 GS350 and about two weeks ago I found the car in the middle of the night with the low beeping noise and dead battery for no apparent reason. For me, it did turn out to be the key fob being left to close to (AND) outside of the car “while locked”. I usually leave the keys in the car with the windows down and the doors unlocked which is why (I) never had this issue before (or since). That’s actually the “key” (no pun intended) to my issue. The Lexus GS350 has a proximity sensor which turns on the lights under the side view mirror(s) and interior overhead lights so that their is some illumination when approaching and entering the vehicle in the evening. This feature does not engage if the doors are unlocked and/or the keys are still in the car. The car also has sensors letting it know if the fob is still inside the vehicle so that you don’t accidentally lock the fob in the car. This has come in handy more times than I care to admit. That said, I suspect that the fob and proximity sensor were engaging the active lighting feature on and off for several hours and ultimately depleted the battery. Since this happened, I have returned to parking the Lexus in the garage. windows down, doors unlocked, and keys in cup holder and I’ve had no further issue.

If this is not your issue, then as posted on here previously, I would test the amps being generated by your alternator. Clean your battery terminals. Replace the battery if alternator is “consistently” putting out the correct amps. Keep in mind that alternators usually fail over a period of time so it’s possible to get a sufficient amperage indicating that it’s working as it should at the time you test it. I suggest letting it run for ten minutes or more, turn on as many electrical components that can safely be engaged (AC or heat, high beams, radio, hazards, etc.(NOT wipers - they may scratch the windshield). I would also test it a few times to ensure amperage is steady. Low battery in the fob can also trigger the alarm intermittently and cause battery to drain. One other thing to check is if you have a parasitic energy draw. Check any non-factory electrical accessories that may have been installed (I.e. hardwired radar detector, amplifier remote wire, additional lighting, etc.) and confirm that they are not drawing power from the battery while car is off.

I hope this helps at least one person. Good luck everyone.

Ed in Orange, CT.