Lunging type action when braking.

[umpkey]

Hello,

2024 Lariat Hybrid. I am having an issue and not sure I will explain this correctly. When stopping/braking as I get down to lower speeds i am feeling like the truck is lunging forward. Braking is not affected so I don't feel it is a brake system issue. It is almost like while braking the accelerator is quickly pressed for a brief second then let off. I don't know if this is an issue with the regenerative braking system or maybe a transmission issue. Bottom line I am going to the dealer on Monday to make an appointment to have it looked at. I was looking to see if anyone else has experienced this and can tell me about it so I have a little more information when I go talk to the service advisors. I also apologize in advance if this has already been discussed, but I couldn't find anything.

Thanks everyone in advance.

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[HeyBales]

You should get the EV Coach view so you can see what is happening.

It'll show if you are actually in regen until slower speeds, at which point the pads start getting pressure.
Abouts 8 mph.
But you could be going into the pads earlier because of going past regen - or back and forth.

EV Coach will show that.

 

[umpkey]

You should get the EV Coach view so you can see what is happening.

It'll show if you are actually in regen until slower speeds, at which point the pads start getting pressure.
Abouts 8 mph.
But you could be going into the pads earlier because of going past regen - or back and forth.

EV Coach will show that.

I will keep an eye on that. Thanks

 

[Ranko Kohime]

I am experiencing the same in my ‘25, and the EV coach does not show it, it acts like nothing has happened, but because I run a ScanGauge, I can tell it is dumping the regen, and rather abruptly.

My Prius used to do the same if something required it, high SoC, battery temperature, etc, but this seems to happen any time it’s cold out, regardless of the battery temperature, or the SoC.

Bad programming by Ford.

 

[HeyBales]

I am experiencing the same in my ‘25, and the EV coach does not show it, it acts like nothing has happened, but because I run a ScanGauge, I can tell it is dumping the regen, and rather abruptly.

My Prius used to do the same if something required it, high SoC, battery temperature, etc, but this seems to happen any time it’s cold out, regardless of the battery temperature, or the SoC.

Bad programming by Ford.

Well - it does "dump" the regen when you get slow, and abruptly, as the pads are only used.

And if the HVB SOC is 70% is stops sending traction motor elec to the battery and sends it to the generator motor to spin the engine for air braking to waste it.
That's at higher speeds but it can happen at 10 mph if the situation is right.
That ICE braking is different rate than regen braking so it could feel abrupt, if it happens right.

The EV coach or power meter in 25MY is needed to see if totally in regen, and sorta gives clue if up at the 70%.

 

[Jose A]

My ‘24 XLT Hybrid “lurches” sometimes when in Drive with my foot on the brake. Brakes sometimes grab when slowing down. Doesn’t do it all the time so I haven’t taken it to the dealership. Anyone else have this problem?

 

[CarWal16]

I'm sure I've sensed that while braking, but more noticeable is on rare occasion at a stop, while pressing on the brake, I can sense the engine/transmission "pulsating" every second or so. Usually only happens once at the beginning of a drive, then disappears.

 

[Kenv24]

Remember guys....the 'bouncing' while stopping AND the pulsing while stopped on a cold truck have both been discussed in several previous posts. Use the search or look at the bottom of other braking related posts.

 

[Glen Baker LLC]

I'm sure I've sensed that while braking, but more noticeable is on rare occasion at a stop, while pressing on the brake, I can sense the engine/transmission "pulsating" every second or so. Usually only happens once at the beginning of a drive, then disappears.

Check out this thread. Great explanation by @Mavster Mechanic
post #106 & #110
https://www.mavericktruckclub.com/forum/threads/surging-when-stopped-anyone-else.23160/

 

[Ranko Kohime]

Well - it does "dump" the regen when you get slow, and abruptly, as the pads are only used.

And if the HVB SOC is 70% is stops sending traction motor elec to the battery and sends it to the generator motor to spin the engine for air braking to waste it.
That's at higher speeds but it can happen at 10 mph if the situation is right.
That ICE braking is different rate than regen braking so it could feel abrupt, if it happens right.

The EV coach or power meter in 25MY is needed to see if totally in regen, and sorta gives clue if up at the 70%.

No, this is different than the transition from regen to brakes, it doesn't even transition to brakes because the pedal is too lightly pressed, and it happens at higher speeds.

In addition, the EV coach shows nothing of this, whereas at 70% SoC it does. At 70% SoC, or before, normally it will ramp down the amperage gently, in the case described, it slams it off like a circuit breaker is tripping.

 

[Ranko Kohime]

Ahh, so I added Hybrid Batt Volts to my ScanGauge readout, and every time it does this, the battery is rapidly climbing to 250V, at which point the “circuit breaker” trips.

When it does this, I also experience a super narrow electric window on the EV coach, as if it doesn’t think the battery can provide significant amperage. I suspect a bad connection to or inside the pack, I am going to speak to a dealer about it.

 

[Ranko Kohime]

An update, the truck finally threw a code, P0B24 “hybrid battery A voltage unstable“, got it to the dealership with 99,188 miles, and the battery is being replaced under warranty.

I haven’t talked with the mechanic yet, but I suspect it is not the entire battery pack, but rather just the contactor, as the behavior seemed to come and go randomly.

 

[HeyBales]

Very true - unless they got someone specialized in it - easier to replace the whole battery even if just a connector inside.

Glad it got figured out, sorry it had to hit so many times before it was trackable.

Will be interesting to see that workorder notes - if they include how much they figured out, or reached out to Ford tech to assist with.

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