When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hybrid TechnologyUnique topics related to the 2004 -2009 RX400H model hybrid drivetrain and other features/options found only on the RX400H. Please use the main forum for discussion about shared components with other second generation RX models.
I had this vehicle since 2012. I has similar concerns at first. Best not to look or worry about the charging and discharging of the batteries. You do not need to, just drive it like a regular car. I parked and idled the car for 2+ hours before. The car runs the engine when its needs to, will try to maximize fuel efficiency by running things off the traction battery when it can and turn the engine onnas needed to "charge it back up" I used to worry about seeing the indicator drop to the 1-2 bar zone while idle as well as in driving. In short. The screen is meaningless and more for show so owners can see how fancy the system is. I had my share of bad 12v batteries where it failed in 1 yr. Optima batteries are not worth the price tag. Costco/Walmart has easy swaps if it fails early. I still expect 5 years lifespan on them.
There was a recall/update on the inverter/pm module. Make sure that was done.
Maybe my inverter is an issue if that is also affected by a leak in the evaporator. My evaporator had a small leak that was fixed with stop leak and held for a long time. Then a year later the 12v needed changed again so I did that and three yrs later (now) had to replace the 12v (just out of warranty) again. After scanning I did not get any codes like I did prior to changing the battery but I did get live data and 3 evaporator messages that I'm guessing means the leak that was fixed could be leaking again. I just don't know how it would relate to the engine coolant running hot even though the dashboard never shows hot. The highest is halfway between C and H. That's when the VSC comes on again. Here are the pictures with notes: Ignition on no warning lights. Warning light came on midway through this display while driving down my street. Could a leak in the evaporator system cause high temperature in coolant?
It was an A/C Automotive business that did that procedure after finding the leak in the evaporator. They cleaned and cleared the system and told me they could point to the area that was leaking in that part.
I have heard not to do that type of fix yourself.
And it did last for years although the 12v battery went twice in the 4 years after it.
The evaporator part maybe 100 - 200 dollars but it's getting to it and removing the dashboard that takes time and is considerably costly.
If it is the same small leak I'll have to replace the evaporator or the car isn't drivable. sigh*
I know that is part of the problem my last 12v battery upgrade was the yellow top Optima that lasted 3 and 1/2 yr.s which was outside the warranty. I got a near-equivalent gel/ deep cel Diahard this time already and the car recalibrated when I changed it out. So the battery is fine and the Nexas scanner did not find any codes after replacement (recently posted pics).
However, there is something that is causing the VSC lights to come on, and seems to be hot (not with the engine) near the front engine area above where the evaporator is.
I start it each day but can only drive down my street and back to my driveway before the VSC lights come on and the car would not continue to drive.
It's also possible that something is clogged and needs cleaned again....like a sensor. Or there is a connection/wire or hose, that went bad the last time the old battery was going bad.
I'm not giving up. I may try a certified mobile mechanic to diagnose. But after buying new tires in Aug. and then the new battery, my budget is not ready yet.
I don't feel comfortable having it towed to a shop until I can find a decent qualified mechanic. I started my membership here years ago with a post when I had my first experience with the battery and then what ended up being a small leak in the evaporator.
The first shop I was towed to was a total textbook scam. I ended up having it towed back to my house. Got a ride to the Auto parts store to pick up the new 12v battery and changed it myself following the instructions from a member on this board. Then it drove w/o using the A/C and I went to the garage back then that was recommended to me. They found the leak .... you can go to the beginning to read about it if you're curious.
I've learned so much about my car and the year-make 'known' issues in design etc. So I'm glad I joined the board. Even the simple fix of turning the gas cap to click properly made a difference for me to drive to the shop back when I changed the 12 v battery.
And yes, the hybrid shows full even though I'm driving a short distance in that mode. It's fine until it's not. The difference this time is that I can't continue to drive with the VSC light when it comes on.
Is there a separate O2 sensor in the front of the engine or fuel injector that I could clean myself? This all recently happened after having a nasty heavy thunderstorm with lightning that my area is known for seasonally. This particular storm was heavy and windy. I'm still having to vacuum out small tree leaves under the wiper area under the hood.
Do you know if the brake accumulator was replaced under Lexus “extended” warranty program? I started getting error codes after I did an alignment on my 2006 RX400h which should NOT have had anything to do with brake accumulator but $1800 later the codes disappeared. I bought the part from Toyota and had a local shop install it for $800 less than Lexus was charging only to find out Lexus would have done it for free if I had waited a couple of months under the extended warranty. In any case Lexus reimbursed me what I paid EXCEPT for the diagnostics that they did. I saved Lexus $800 but they were too cheap to reimburse me $145 for reading the codes which I gave them before they even hooked up their scanner! Go figure…
Do you know if the brake accumulator was replaced under Lexus “extended” warranty program? I started getting error codes after I did an alignment on my 2006 RX400h which should NOT have had anything to do with brake accumulator but $1800 later the codes disappeared. I bought the part from Toyota and had a local shop install it for $800 less than Lexus was charging only to find out Lexus would have done it for free if I had waited a couple of months under the extended warranty. In any case Lexus reimbursed me what I paid EXCEPT for the diagnostics that they did. I saved Lexus $800 but they were too cheap to reimburse me $145 for reading the codes which I gave them before they even hooked up their scanner! Go figure…
No, I don't know, and thank you for the information.
I'll call and see if they have a record of it being replaced under the previous extended warranty. I'm the second owner of this car and got it right when the extended warranty expired.
It won't hurt to ask.
Do you know if the brake accumulator was replaced under Lexus “extended” warranty program? I started getting error codes after I did an alignment on my 2006 RX400h which should NOT have had anything to do with brake accumulator but $1800 later the codes disappeared. I bought the part from Toyota and had a local shop install it for $800 less than Lexus was charging only to find out Lexus would have done it for free if I had waited a couple of months under the extended warranty. In any case Lexus reimbursed me what I paid EXCEPT for the diagnostics that they did. I saved Lexus $800 but they were too cheap to reimburse me $145 for reading the codes which I gave them before they even hooked up their scanner! Go figure…
Update to this inquiry: I called Lexus and asked about any recalls and service for the same on my car. I also asked specifically about what you mentioned regarding the brake accumulator. The rep stated that there were no recalls on parts for my vehicle and no other service issues on any parts that were done in their system.
I had a mechanic nearby drive and test with his code reader (AUTEL) just before calling Lexus. The car would drive in engine mode and didn't flag any codes, but it wasn't cycling to hybrid. The engine was kinda rough (imo) while we drove about 4 miles. He was more confident and drove faster than I would, but not recklessly. I'm thinking... it got dirty when the fuel was low.
When we got back to his shop he continued to search his reader on the hybrid side and had a code that related to 'HV/EV control system regenerative malfunction' C1259.
Then P3013,P3030 are pending with a description disconnection between batter and ECU then battery block 3 weak. both pending....
I drove it home less than a mile. Then realized not once was the 12v disconnected for a few minutes then reconnected so he could see how the car recalibrates.
I did it and sure enough it started and cycled to Hybrid mode. I drove it down my street and back and watched in the display on the dashboard how it was powering the car or charging etc.
Also, sure as usual the VSC light came back on.
The next day I rechecked the fuses in the engine area and switched one of the ECU 7.5 with the extra from the lid. It hasn't been 'stuck in engine' mode since.
Although I only drove today to fill from 1/4 tank to full. I plan on adding a fuel cleaner tomorrow. Even though I'm sure something else is draining the 12v and or not connecting properly for that VSC and occasional Eng light to turn on.
The point in taking it to this mechanic btw was due to the last codes that recommended checking spark plugs and coil 'performance poor'.
He checked visually along with his scanner and said it seemed fine.
I'm educating myself on the fuse area under the glove compartment next. It can't hurt right?
Good job Patricia. It is important to check performance after 12V battery isolation. Quite often with the 400 you can resolve yourself – it is a relatively un-complex vehicle by today's standards.
I do recommend a trickle charger to keep the 12V in good shape – especially if you are a short journeyer or live in cold clime. The 12V parasitic drain on the 400 takes up a lot of forum space. It is quite bizarre in many cases. Again I recommend the trickle charger Cheap V slow feed charger
As far as fuses are concerned – you know when one has blown – you can see the break and you should get a code/dash warning.
I have a 2005 400. I run my AC all the time as it acts also as a cabin dryer – not much call for cooling in the UK (I had a very serious water leak problem that got to the hybrid battery – so keeping dry has been key for me)
x12 vlt battery was discharging and needing to be jumped if an accessory was used , emergency flashers used etc, 2 weeks later , 400 , while driving made thumping noise , slowed down , pulled over and CHECK HYBRID SYSTEM......check engine light, CSV /AWD and tracking indicator lights on , Warning red triangle exclamation has been on and i was told tracking issue do not woryy car drove in electric motor mode to mechanic's 2 blocks; he no longer work on hybrids, used to work at Lexus .,He dint know why the engine will start to turnover but will not , Code pulled up by OBD and Torque Pro software ,P0351: , Coil, wiring harness, ECM no default codes , ...P2241 , P2238Positive Current Control Circuit Low 02 CENSOR CODES . IT IS NOT THE ACTRUAL CENSORS THAT ARE BAD , says cousin who works on his own cars Is it the Hybrid battery at 50 percent . Cell # 12 dead , 13 also i think per Dr.Prius .com software
11-28-23, 04:06 PM
50 % hybrid battery and what it is effecting