Brakes in Hybrid

[ACJ]

2026 4Runner iForce-Max Hybrid. Ever since I bought my 4Runner, last January, the brakes have felt a little off. Sometimes this is very noticeable while backing out of a parking space. This became dangerous the other day. While backing someone stepped behind me at the same time my brake pedal went from stiff to soft.
I took it to the dealer and left more worried than when I arrived. They told me they found nothing and gave me a bunch of lame explanations. I got my drivers license in 1970 and have enough mechanical experience to have replaced head gaskets, lifters, bake discs ect; their explanations made no sense to me. I called Toyota Brand Engagement. They recommended a second opinion and they contacted a second dealer. The second dealer's initial assessment was nothing wrong so they wanted to keep it for a day.
During that day I did some research. I did not know brake-by-wire systems existed in cars; a little scary. A sensor in the pedal tells a computer how far the pedal is depressed and how fast it is depressed then the computer controls your brakes. You do not feel actual braking in the pedal. A Stroke Simulator gives you fake brake pedal pressure. The Car Care Nut has a good short video on YouTube.
AllData now has the 2026 4Runner Hybrid Shop Manual on-line. I did a search for brakes and did not find anything but now realizing the brakes and the brake pedal are kind of two separate entities I did a pedal search. In that search I found my exact backing from a parking space problem.
When you open the driver's door you can hear a sound coming from under the hood. That is the Stroke Simulator Accumulator charging up. It will also charge when you start the engine. But if you get into the car and sit for a “long time” without starting the engine like i do all the time, the Accumulator will drain. Then start the car and start driving before the Accumulator charges, the brakes pedal will not function properly till charged. Toyota says this is normal.
I went to pick up my 4Runner from the second dealer. They said they found nothing. I handed them a printout from the Toyota 2026 4Runner Hybrid Shop Manual. Told them because it was there it was a known condition and left with my 4Runner.

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[HVLA]

Weird. Havent experienced any issues here. I am curious though. Why would you sit in your vehicle for long periods of time with the vehicle off? I have sat in various vehicles for long periods of time for one reason or another, usually waiting for someone, and have always have the vehicle on so I can run a/c, heater, radio, etc..

 

[ACJ]

I go to Starbucks, go inside, Get my coffee, go back to my 4runner, place. My tablet on the steering column read and write emails, do work. I might work there for over an hour.

 

[HVLA]

I go to Starbucks, go inside, Get my coffee, go back to my 4runner, place. My tablet on the steering column read and write emails, do work. I might work there for over an hour.

I guess if you live in a super mild climate and dont like music it makes no sense to turn the vehicle on.

 

[Dead Horse]

I guess if you live in a super mild climate and dont like music it makes no sense to turn the vehicle on.

Right?

If I did that here, I'd pass out in the first three minutes LOL

 

[Hodgeman]

I've experienced that in my 2025. I wrote it off as a once off, thanks for the explanation.

I knew the brakes and the brake pedal are a disconnected system...heck, the computer applies the brakes more than I do but didn't know how the feedback worked.

 

[GAPx]

Thanks for the detailed and fascinating write-up. And BTW, not sure why your excellent thread turned into a treatise on your personal habits! Thanks, still a good read.

 

[lrettura]

2026 4Runner iForce-Max Hybrid. Ever since I bought my 4Runner, last January, the brakes have felt a little off. Sometimes this is very noticeable while backing out of a parking space. This became dangerous the other day. While backing someone stepped behind me at the same time my brake pedal went from stiff to soft.
I took it to the dealer and left more worried than when I arrived. They told me they found nothing and gave me a bunch of lame explanations. I got my drivers license in 1970 and have enough mechanical experience to have replaced head gaskets, lifters, bake discs ect; their explanations made no sense to me. I called Toyota Brand Engagement. They recommended a second opinion and they contacted a second dealer. The second dealer's initial assessment was nothing wrong so they wanted to keep it for a day.
During that day I did some research. I did not know brake-by-wire systems existed in cars; a little scary. A sensor in the pedal tells a computer how far the pedal is depressed and how fast it is depressed then the computer controls your brakes. You do not feel actual braking in the pedal. A Stroke Simulator gives you fake brake pedal pressure. The Car Care Nut has a good short video on YouTube.
AllData now has the 2026 4Runner Hybrid Shop Manual on-line. I did a search for brakes and did not find anything but now realizing the brakes and the brake pedal are kind of two separate entities I did a pedal search. In that search I found my exact backing from a parking space problem.
When you open the driver's door you can hear a sound coming from under the hood. That is the Stroke Simulator Accumulator charging up. It will also charge when you start the engine. But if you get into the car and sit for a “long time” without starting the engine like i do all the time, the Accumulator will drain. Then start the car and start driving before the Accumulator charges, the brakes pedal will not function properly till charged. Toyota says this is normal.
I went to pick up my 4Runner from the second dealer. They said they found nothing. I handed them a printout from the Toyota 2026 4Runner Hybrid Shop Manual. Told them because it was there it was a known condition and left with my 4Runner.

Great information, thank you for taking the time to chase it down. Do you know about how long it takes the accumulator to fully charge? That would be helpful. Thanks again.

 

[ACJ]

Great information, thank you for taking the time to chase it down. Do you know about how long it takes the accumulator to fully charge? That would be helpful. Thanks again.

I can hear it when I open the driver's door and it stops about the time I am seated. Maybe 5 seconds. Today, after sitting in starbuck's parking lot for about 45 mins, I pressed down the brake one time before starting the engine. I heard the pump run for a few seconds and the brakes worked normally. I had told the dealerships, before studying the brake system, that I had no problems if I pumped the brakes before backing . They said that would do nothing.

 

[bakutheleo]

Interesting, I always wondered what that sound was! "Fill function in here" by wire is very common. Likely backups are in place, plus very reliable in the first place. Navy vessels and fighter jets have been using this for a long time...if good enough for them it is probably good enough for our cars.

Good to know though. It ony takes a few moments for that sound to stop though--I would never start the vehicle and put it in gear that fast anyway--good to give it at least a few seconds to start up.

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