yumcax

First, I apologize profusely for rehashing this topic again. I've read through as many threads as I can find and still haven't quite get found answer a definitive answer.

My RX400H has the dreaded no-start with Hybrid System and VSC warnings problem. The codes were actually first thrown while driving the vehicle and as soon as it was parked, it wouldn't start again. I can start it in the typical fashion of disconnecting the battery negative for a minute or two and reconnecting. Driving the car, however, fairly quickly triggers all the warning lights/codes again and the no-start problem occurs after the ignition is turned off.

Today I checked voltage on the accessory battery and it read right around 12v. Since I had the car at home this time, I tried jumping the 12v battery. Jump starting didn't help in starting the car, but disconnecting/reconnecting battery did. After starting the car via the battery disconnect trick, I let it idle/stay in ready mode for 15 minutes. Voltage check on the battery showed something like 12.8v but was dropping fairly quickly. I was able to start the car and drive it for longer than before without the ECU throwing codes.

My question(s) is/are: would it be worth throwing a new 12v battery in or does it seem like the charging system for the 12v (or something else?) might somehow be malfunctioning? I thought it was strange that the car wouldn't start with a jump, but perhaps that's due to the warning codes that were initially thrown because of low battery voltage.

Edit: I understand that voltage alone says basically nothing about the condition of the battery. I only thought it worthwhile to mention in case low voltage is what triggers the ECU to prevent starting the hybrid system.

smassey321

Take your 12v battery out and have it tested at an auto parts store. If it tests good, scan for codes with a scanner capable of reading Toyota hybrid codes. Your answer probably will be there.

Your 12v batter is not just a accessory battery. It boots up the hybrid systems which "starts" the car. The 12v battery is then charged by the hybrid system. If the 12v battery is bad or has bad connections, I could see odd things like this happening.

And monitor voltage while driving. See if the voltage dips at the point when the warning lights trigger.

yumcax

Thanks for the reply. I had the battery tested today and it checked out as "good", but it was at a Napa store so I'm not sure if the tester they used was as thorough as it could be. I cleaned the terminals and connectors and reinstalled the battery.

The car keeps reverting to a no-start condition with the VSC and Hybrid System warnings, usually after short periods of driving. I did notice that the battery voltage was down close to 12 after the warnings came up again, whereas minutes earlier it had been up above 12.5.

One other thing I noticed is that I can hear what sounds like the traction battery fans running on startup. I don't recall this happening before. They run for perhaps ten seconds and then shut off. Typically the codes/warnings come up again after 1-5 minutes of driving after reconnecting the battery negative.

Weighit

If you have a charger, pull the battery and charge it for a few hours then reinstall. See if any change in your problem.

vscalais

iTrader: (1)

12.8 volts is too low. Should be around 14 volts from alternator. I would immediately replace the battery.

yumcax

My goal now is to get a fully charged battery into the car to see if the symptoms resolve. I don't have an OBD scanner and the nearest dealer is 120 miles away, so my next action will probably be to simply have it towed to the dealer and cross my fingers. I'm just not sure if it's worth paying a local shop (I live in a small town and I'm almost certain none of the shops here are hybrid-certified) to pull the codes, only to end up still not having a solution. I've considered getting a scan tool but with my (admittedly low) level of knowledge about these cars, I'm not sure it would help me troubleshoot the issue unless clearing the codes simply made the problem go away.

I'll update this further if anything else comes to light.

vscalais: The RX400h doesn't charge via an alternator.

thomas1

The hybrid doesn't have an alternator, it gets it charge from the hybrid battery.

yumcax

I went ahead and charged the battery for a few hours, reconnected it and turned ignition on. The battery shows a steady 14.3v while the ICE is running and around 13.8v when the ICE shuts off. The codes/warnings still popped up pretty quickly with no apparent change in voltage, but I thought I noticed an uptick in idle rpm when it happened. On shutoff, the battery was still holding 12.4v fairly steadily.

When the ICE shuts off but the ignition remains on, there's a distinct whining sound from under the hood somewhere that I can't easily trace. I have no idea, obviously, if this is related or not.

At this point it seems that I don't have much choice but to get it to the dealer and just see what they find.

Would it be at all worth it to have someone scan and clear the codes just to see if that works? I'm still not clear on just what gets erased when the battery is disconnected or if the codes are wiped from the ECU at that point. I suppose I'm reluctant to pay someone to merely read/clear the codes if they can't do relevant repair work.

Thanks again for the replies. I'll update this with any relevant information.

smassey321

This is what I use to scan for codes. http://www.ebay.com/itm/Mini-VCI-Dia...-/272486156179

The Toyota codes can be very specific and will point you in the right direction. Dealers are only going to want to swap new expensive parts. Used parts are super cheap for hybrids because they rarely go bad. Hopefully your issue is something simple like a loose connection somewhere.

Have you checked your rear floors for water? Some leaks can get the hybrid batteries wet and odd things happen. Search around.

yumcax

Do those mini VCI cables actually arrive with the necessary techstream software or is that something I have to 'find' elsewhere?

Water was/is certainly a consideration. The problem started shortly after the temperatures warmed up after 40 days below freezing. It may just be a coincidence, however, as initially there was only the tiniest bit of moisture on top of the carpets (probably from small amounts of snow from boots, etc) and by now even that is gone. I'm guessing there would have to be standing water in the battery compartment? How hard is it to get to the traction battery for a visual assessment of this? I'm assuming that reading codes is the next logical step before attempting any other unnecessary and/or harmful DIY interventions.

smassey321

I ordered mine many years ago. Back then you had to "find" the software. It is pretty easy to get setup compared to other cars I have done this with. I have removed my rear seats to vacuum under there. It was not that difficult and I could see the external case of the battery when the seats were out. You may be able to pull the carpet back on the edges and get a hand in there.

jooksing82

I think mine came with the software.

I came across this article a while back..They say if the drain hole gets clogged then some water may accumulate around the traction battery.

http://artsautomotive.com/water-leak- causes-p0aa6-inf- 526-612- lexus-rx400h/

yumcax

I wanted to post a follow-up to this thread now that we finally got the car towed to the dealer (90 miles away, so had to update AAA before towing, etc.). The fact that the problem occurred as soon as the weather warmed above freezing for the first time in over a month was significant: the service dept. found .5" of standing water in the pan below the traction battery. The drain for the pan is apparently working properly, although given the temperatures around here I wouldn't be surprised if it was previously frozen. The relay for the traction battery also happens to be located in said pan, so the water had shorted it out. I believe if I'd been able to scan for codes, the relevant code for the Hybrid System would've been related to an 'isolation fault' from the shorting out of the traction battery relay. So far, they haven't been able to determine the entry point for the water, which is worrisome.

The only silver lining is that pulling the traction battery to replace the pan and relay will likely run less than $2000. Other battery related issues yield a much higher price tag and we were sort of preparing for the worst. I know that it's possible to DIY hybrid system repairs, but lack of an appropriate work space and the non-zero chance of fatally electrocuting myself made the stealership a more viable option.

Thanks for the replies and information and hopefully this thread will help someone else when the dreaded warning lights flash.

thomas1

Thank you for coming back on and describing the resolution, little do you know how this will help someone else down the road. Sorry it cost so much, (seems outrageous to me) but best of luck.

yumcax

The dealerships are always outrageous, but I was expecting worse this time. As for posting resolutions on forum topics: of course! I daily drive a 1990 VW Fox (the Lexus belongs to my GF) and do all the work on it myself. The Fox is probably the weirdest VW to own at this point aside from the Thing, so the Fox forum on VW Vortex is one of the most supportive, online forums for DIYers I've seen. It's nice to see that there's a similar place for Lexus owners! Without these forums, we'd always be going to the 'pros' with wheelbarrows full of money. Cheers!