Bizarre regen/brakes issue!

[RikiTiki]

interesting..

I like the detail about how you held your foot on the break after the car was off for around 5 minutes.
This sounds like doing this *Could* have caused the breaks to reset to this new start position once the car
is turned back on if its held during the entire EV (off) then back to (on) time period.
(Not the most natural event since most people dont hold breaks down when parked *after the car is off*
but worth looking into for those that live on steep hills which might have this happen a bit more then flat land dwellers.) -_^

Hope this helps,
RikiTiki

 

[IBELEAF]

Brought it back from service... As expected nothing showed up in the log and obviously reproducing issue is out of question. I don't think I was imagining things because my wife was present and can attest this was indeed a bizarre issue. I am still thinking there is some sequence of steps that needs to be done that would trigger that somehow...

 

[aqn]

Earlier today my Leaf got "stuck" from the start in some sort of brake/regen mode and brakes were much harder to push. Basically, if I let go of accelerator on the flat surface my car immediately would start braking with 4 regen bars. I drove like that for couple of miles then stopped and powered the car off thinking that would go away. Suddenly another issue, I could not turn the car back on because it kept asking me to push brakes. After several tries I finally got it turned on by pushing brakes as hard as I could and the earlier issue went away... So, got me a little worried and I was trying again to reproduce this issue again, but no luck so far. [...]

Seriously though, sounds like there is an issue with the brake booster so it was kicking in more regen as a safety method to slow you down.

Yeah, the increased brake pedal does point to brake boost failure. It could be the brake pedal stroke sensor (which may also explain your starting problem) or the master cylinder pressure sensor. It can also be a bug in the Brake Control Module (BCM), which would appear to be more worrisome. I gather there was no warning light(s)? I would take it to the dealer and see if there were any DTC's stored.

 

[abasile]

I don't know if it's related or not, but I've sometimes noticed the brakes are inexplicably significantly more grabby than usual. This has happened to me several times and I've been unable to figure out a pattern...

This happened to me for the first time today. After driving for 15+ minutes through damp, 37° (!) fog, we descended Kuffel Cyn. toward Lake Arrowhead. For the first minute or two of this descent, which involves continuous regenerative braking, the brakes seemed especially sensitive and jerky feeling. Every time I used the brake pedal, the amount of regen indicated on the Energy Info screen spiked. This behavior did not last long, though.

 

[DaveinOlyWA]

Btw, just to add another observation, I did hear one clunk as I was driving...

probably already mentioned but do you use the parking brakes at all?

 

[adric22]

You know, I just thought I'd mention something. May be totally unrelated but it took me by surprise a few times. I typically drive my leaf in Eco mode. Well, there is a big hill to go down when leaving my house. I've noticed that when the I just unplug the car and it has a full charge, regenerative braking does not work at all. So then I have to press the brake pedal a lot harder than usual to engage the friction brakes. The first few times this happened, it felt really odd. Since I've driven a Prius for many years, I'm quite accustomed to the feel of regen and since the Prius pretty much never lets its battery get full this is not something I was used to.

 

[aqn]

You know, I just thought I'd mention something. May be totally unrelated but it took me by surprise a few times. I typically drive my leaf in Eco mode. Well, there is a big hill to go down when leaving my house. I've noticed that when the I just unplug the car and it has a full charge, regenerative braking does not work at all.

Same here: my commute to work includes a downhill, something like 288 feet drop over 2500 feet (12% grade). No-regen-on-full-charge has been commonly reported on here.

So then I have to press the brake pedal a lot harder than usual to engage the friction brakes.

Hmmm, I have not noticed that... Certainly, the brake pedal effort, going down this hill with a full charge and no regen, has not been noticeably different than when with an not-full charge and with regen.

 

[IBELEAF]

probably already mentioned but do you use the parking brakes at all?

No, I would not dare to drive with parking brake, especially at freeway speeds when this happened. The thought, however, crossed my mind to try it later just to see if this was the case. On the other hand regular brakes required more pressure then normal, so that's basically removes any doubt that I could possibly had parking brake on. Also, I did not touch the parking brake when I restarted the car.

 

[abasile]

I've noticed that when the I just unplug the car and it has a full charge, regenerative braking does not work at all. So then I have to press the brake pedal a lot harder than usual to engage the friction brakes.

I don't think you're observing anything abnormal. Normally the car applies regenerative braking when you take your foot off the accelerator, providing deceleration similar to "engine braking", more so in ECO mode. (In ECO mode I don't need to use the brake pedal much because of this.) But with the battery full and that regenerative braking absent, the car will simply coast. As a result, it could be necessary to use the brake pedal more than you would otherwise have to.

 

[Ingineer]

Btw, just to add another observation, I did hear one clunk as I was driving...

That was the small child you hit while watching the eco display. =)

 

[gascant]

When I leave the house in the morning with a full charge, it's probably the only time that the friction brakes kick in fully at any appreciable speed. I wonder if brake dust or road stuff could cause the grabbing until it wears away. Commuting in ECO mode, I can see it's going to be a long time before I need to replace brake pads. Has anyone noticed how big the rotors are?

 

[aqn]

When I leave the house in the morning with a full charge, it's probably the only time that the friction brakes kick in fully at any appreciable speed. I wonder if brake dust or road stuff could cause the grabbing until it wears away. Commuting in ECO mode, I can see it's going to be a long time before I need to replace brake pads. Has anyone noticed how big the rotors are?

And that the rear rotors are larger in diameter!

 

[GeekEV]

Anyone seen this thread: http://www.mynissanleaf.com/viewtopic.php?f=30&t=4467 ? It sounds like a similar variation...