Saw the same issue when my Avalon 12v battery went low. Jump started it with a battery jump pack and it was fine afterwards.

The electric parking brake motors must use a good amount of current.

 

Sounds like a low battery to me also. Especially since you said you were loading the car up for a trip, that's when you leave the doors open and as you said use the liftgate a lot. Charge the battery for a couple of hours and it should be good to go.

 

Car did start after being charged for an hour. Thanks for your help. Still charging at 10 amps. But that is plugged into the house.
I'll leave it plugged into the house until I have to leave. I suspect it will get me there. But it makes me wonder. We carry around a pretty big battery. Is there a way to force that big battery to charge the little battery?
I think there is a catch 22. Can't use the big battery to charge the little battery. Until the car is "ready. ' The car is not ready until the little battery is ready. The little battery controls everything

 

Toyota hybrids are very careful to maintain a "medium" state of charge on the traction (big) battery. The only way the vehicle can recharge the 12V battery is by drawing from the traction battery. If the traction battery is allowed to excessively discharge it will be unable to "turn over" the engine. Now you are stranded until the vehicle can be brought in to a dealer to replenish the roughly 300V traction battery. It is better for the 12V battery to go dead than to deplete the traction battery.

1. The hybrid 12V battery does not have much reserve capacity. It can be depleted much sooner than a traditional "starter" battery.

2. A hybrid requires little current from the 12V battery to start the vehicle but does expect a solid 12 volts.

3. Because of #2 it is possible to "jump" a hybrid 12V battery using a pair of light gauge alligator clips and a fully charged lawn tractor, motorcycle, trolling motor, etc. 12V battery.

4. Best practice (assuming adequate ventilation) when drawing frequently from the 12V battery over a short period of time is to leave the vehicle in the "Ready" condition so the engine will start as/if needed to replenish the 12V battery. Caveat: Don't forget to turn the vehicle off when done!

Is there a way to force that big battery to charge the little battery?

See #4

The little battery controls everything.

Most certainly true.

 

You want to charge the 12v battery as much as possible. But if you expect to be using all of the accessories for a long period of time such as loading, leave it on a charger.

 

The OP stated that he was going on a long trip (sorry for the loss of your father BTW) so if the battery is in good health then the hybrid drive system will have time to fully recharge the battery. The parking brake malfunction was just a symptom of the low battery. Simply put the big battery can't start the car because the vehicles electronics (including all the computers and relays) are 12V based. With a dead or weak 12V battery the computers can't come online and without the computers the car can't operate. The big battery is just to power the electric drive motors, start the engine and recharge the 12V battery.

My guess would be the frequent opening and closing of the lift gate while loading up drained the 12V battery.

 

Mine starts. But the brakes are super sensitive. So much that I can’t back it out of the garage. Could this be from a low battery too?

 

I am having the same issue with my RaV4 Hybrid 2024. Just went out to start it and got the same message. Cant start it.

 

The solution is above... charge your 12V battery in the back of the car. Hybrids only need for the 12V battery to power the various electronics on the car; the "big battery" (traction battery) is used to start the engine.

It sounds like it's not hard to kill the 12V battery by using any accessories (lights, radio) too long when the car is not in on/ready mode.

 

mine did that on 21 hybrid platnum - jumped it and running fine, but now check engine light on? should i be concerned? any way to get that code checked without going to dealer or reset the check engine light?

 

Same issue with my 2023 siena hybrid. Worst part is I can't even open trunk to jump the battery in rear. Please help.

 

Welcome to the forum @joshisandi !



There is more than one way to jump a Hybrid 12 volt battery.
It can be done from the engine compartment.

Since this is the Highlander Hybrid forum, I don't have a Sienna to look at but I suspect the engine compartments are very similar.
Open the hood and remove the cover from the fuse block that is right above the driver's side front wheel. There is a red safety cover (circled in green, see below). Lift this cover and you should find a 12 volt battery positive (+) jumper clamp connection point. Find a good ground point on the engine block for a negative (-) jumper connection. You don't need much of a jumper battery to "boot up" a Toyota Hybrid. A decent lawn mower or motorcycle battery would probably work.

 

Don’t open the driver door. Opening the driver door tells the brake line to prime and it tweaks. So you have to climb in and out the passenger to jump start it. Ridiculous. This happens occasionally to my 2021 Siena. I get dismissed every time I bring it in for this problem so I haven’t found a solution. They refused to replace the 12V but I’m pretty sure this is the problem. I am woman so they give me a lot of dismissive tone.

Otherwise if you jump it after entering the driver side it will jump it and lights will come inn but not turn completely on the ignition.

 

If you're convinced the 12V battery is the problem, replace it. Then you can stop crawling in the passenger side.

 

I'm 90% sure Toyota does not keep the 12V battery properly charged..

As near as I tell the fancy computer in my car does not provide enough voltage to keep the 12V battery fully charged.

What can I do to fix that?

 

Just curious, what evidence/data do you have to back this up? Is the voltage constantly measured at the battery terminals?
Charging voltage should be about 14 vdc.

 

I had the very same failed 12v problem on my 21 Platinum a few months ago and discovered a couple of things. First I had little or no luck using the under hood fuse block jumper method. I think part of the problem was my Li-ion portable jumper and how it measures voltage before applying jump current. Using the under hood method also triggered a check engine light which I was able to reset by unplugging the big red wire you see on the left side of the fuse box where the jumper blade is located. Once plugged back in the check engine light was out. I ended up jumping the 12v directly but this was a hassle because you can't open the tailgate without 12v power. Very frustrating you have to crawl back there if you need to jump the 12v battery directly. I trickle charged the 12v to recover it enough for a normal start the next day. In the end the dealership agreed the 12v battery was failing and they replaced it under warranty. Of note they replaced the original AGM battery with a Toyota brand traditional flooded lead acid battery.

 

In the end the dealership agreed the 12v battery was failing and they replaced it under warranty. Of note they replaced the original AGM battery with a Toyota brand traditional flooded lead acid battery.

Seriously? I don't own a hybrid (conventional ICE Highlander here) but the hybrid 12V battery is mounted in the passenger compartment, right? That would seem to be very dangerous..... an AGM is sealed but a conventional flooded battery is not and will vent hydrogen and oxygen during charging. Hydrogen + oxygen + ignition source (like the brushes in a motor) = kaBOOM!

Paul

 

I also am having this issue. I’m dead in the water in my driveway… I left my RAV4 Prime plugged in while the car ran for about 15min or less. I’m getting the no parking brake error and the car won’t start, even though it was running whole charging… I don’t have anything to charge the 12v battery with… or to check it…

 

I had this for a very brief moment when I took apart center console between the seats in order to upgrade USB ports to USB-C and had to disconnect the parking break button next to the shifter. The car worked fine after about 2 minutes.

 

European cars have had the 12V battery in the trunk for decades, this is nothing new. Actually, keeping it out of the hot engine compartment is better for battery life.

 

The flooded battery is designed for internal use with a vent tube port.

The flooded battery is designed for internal use with a vent tube port.

Confirmed, not a risk, as have visually observed the battery is vented to the outside of the vehicle.

 

I have a 2023 High Hybrid Platinum & got stuck in a Costco parking lot as it would not start panel message "parking brake unavailable" No ignition, couldn't open rear to jump battery. so tow driver jumpstarted it from engine compartment area. Towed it to Toyota & got was told battery had 2 dead cells so all electronics went kaput. Service advisor said it's a known issue & the new HH's will get a better battery. My battery was changed from a 345 cca to a 540 cca Interstate battery. Important to note I haven't driven the car in a week...I read in the HH manual the battery can discharge when not driven. I have trickled charged (solar) my 2006 4Runner for years w/ no problems & wanna put a solar panel inside the rear bed next to the battery. I know the solar panel won't generate optimal output, but you don't need much when trickle charging. Anyone else trickle charge their Highlander w/ a solar panel?