Hello,

I have HS250h and drive it for about 3 years already with no big issues so far.
Last Feb I had to jump start since battery was low. Not sure how related it is to the issue, just mentioning it.
Since this summer (4-5 months after the jump start) my Navi started resetting randomly but very rarely. Went to the dealer, they could not find issue, removed the Navigation unit and checked it. They saw that one solder on the motherboard looks strange and that was the excuse warranty does not cover the repair (another topic anyway). Offered me to buy second hand Navi (not cheap..., not sure this is the problem anyway) since no new ones are available for such old model. I wonder whether the issue is in the Navi at all so I look for similar experiences and advices.
The story so far:
- I checked the 12V battery at a car accessories store, 50% charge left, 12.45V. No need for immediate change.
- I checked the fuses related to the radio/navigation (both engine compartment and next to driver box). No issues there.
- When the dealer checked the navi, they took it out completely for a few weeks. Issue remained so it is not loose connector.

- Random resets, had them in summer, have them now winter, freezing mountain so i think it is not temperature related;
- have it regardless of mode, stopped vehicle or moving on highway;
- With the reset I see the clock is also blinking, but, no effect on Front lights, AC, panel, top lights. It is localized to the Navi unit more or less. When reset, i often hear a click noise, I found out it is from one of the speakers (as if the power was cut off suddenly);
- If I don't touch the car for 1-2 weeks, I can have 2-3 hours drive with no issues at all (navi used, loud music). Then a reset comes. With everyday use resets get more often until the moment I have constant resets with black screen. From time to time I will still have the starting screen, probably a few min normal operation.
- since 1-2 weeks I see my DVD is not working also;

Any ideas/advices are most welcome!

 

From the sounds of it, the symptoms are of a 12 volt battery that is has failing internal cells. You reported to have jump started the vehicle several months ago, did you replace the 12 volt battery since? If not, I would replace the 12 volt battery before doing further troubleshooting.

 

Thank you for the answer! Bad battery was my initial thought. I had it checked by the dealer during my 6 month check just a month after the jumpstart before any issues with Navi. They didn't say it is bad but recommended to change. A few weeks ago I went for 1 year check, report says battery is in perfect condition (never changed it though). In the last 1-2 weeks I had a little time to play with the car myself and clarified the symptoms in the first post. Battery/power supply sounds as the main issue although I am not sure how the whole electrical system is connected. This made me check the battery again with another place (autoparts dealer, not the Toyota/Lexus one). Just to clarify, if you have experience/knowledge about it:
- wouldn't the hybrid battery power the navigation system in ready mode? this was my first thought and I expected to localize the issue to low hybrid battery/different driving mode when the system will switch from hybrid to 12V (switched between normal and eco). No change though. It is not very clear from the multiple explanations I found. Basically, it says hybrid will do all, 12V is just to start the hybrid battery and for some electronics. Interesting is, I don't see problem with anything else which makes me think infotainment is hooked up only to 12V and the whole circuit relies on hybrid battery charging the 12V, which provides power for the infotainment system. Is this correct?
- I am not sure how bad battery affects the car and you mention the symptoms are for such case. Are my assumptions correct? When I don't drive the car probably the bad cell/s are able to accumulate some energy that would allow me to drive with no issue for 2 hours. Then we just have bad cell. With this cell we do not get enough current to supply the infotainment so it would randomly drop/start depending on the collected charge? Is the not working DVD also a symptom?

Than you very much for the first answer to give a direction!

 

My 12 Volt battery was checked by the dealer three weeks ago and given a clean bill of health. On Friday my wife complained the seat was moving slowly. Later in evening the the car was posting messages claiming the key was not detected. When my wife tried to go to work the next day, the car wouldn't start and the seat wouldn't move. Only half of the warning lights were illuminated on the dashboard. When I checked the 12 volt battery it was down to 9 volts. Needless to say, a new battery from the Toyota Dealer cleared things up. On the HS250h, very strange things can happen when your 12 volt battery is failing. I didn't head the signs and wife got stranded in the garage.

 

As posted by others low voltage due to a failing 12 volt battery can cause all kiinds of seemingly random problems. The simple and best possible solution and test is to just get a new 12 volt battery. If you have the original you need one and it will help narrow down the reboot issue if it continues. You cannot test anything with low voltage as all of the sensors etc are very voltage sensitive. Also cold weather makes batteries weaker and is the season when most batteries fail.
Your best bet is to get an OEM battery from a dealer as there are few aftermarket batteries available.

The good part is you will probably never need another 12 volt battery for the rest of the car's life. My original 12 volt battery lasted 9 years! That is close to normal for a hybrid.

 

I am sorry for the delay. Some update on the case. I changed the battery with a new one.
Started the car and still had the resets. There was definitely some improvement as follows:
- when I start the car i would have few resets in the first few minutes, then no problem for hours (only navi is on, from time to time low sound radio, AC)

few days later, loud music and AC for a few minutes and constant resets again (cannot see the screen at all). After I stop the musc, AC, it would tak some time until system comes back to normal.

From here my ideas are that:
- it is either audio problem (strong audio probably leads to some heating? I am not sure it is battery since it is brand new)
- or, as I saw in some threads when i researched the issue, probably some moisture from the AC

I will continue checking....

 

Check your A/C drain line to be sure it is not clogged. Go under the car and shove some weed eater line up the hose to check it and maybe clear it. Or look for water under the car when the A/C is running. The hose should be in the front under the area between where the driver and passenger feet are placed.
Have you checked for stored codes? Some auto parts stores will do this for you.

 

Thank you for the interesting advice and I think you will be right at the end! I need a few days to test it and I will share the result. Is this the AC drain line on the picture below? Found so many videos and pics for different models and cars, not for HS...
My HS is with right wheel (JP version 2010). Picture is taken behind front wheel, passenger side. Looks about right considering where the indoor AC filter is and judging by the tube size. I am more concerned it is not straight pipe and that it may be a mistake to test it...