ICE on off on off on off on off

I don't believe this explanation. Is it anything more than speculation by a few owners?

I've had this happen to me a few times, and it stops if I power off the car and then restart it. If the rapid start/stop cycling were due to the reason you describe, my shutting the car off once and then powering it up it should not have made any difference. The cycling should have continued once the car was powered up again.

I've also had this happen with less than the full number of bars.

 

I know what this member is talking about He's right My story I was coming down my steep driveway when I had to stop in the middle to wait for my cat to move as I waited the ICE went crazy on off on off every 2 seconds I reached my parking area on level ground and it continued . Bars were at blue waited 15 min to see if it would stop not until I shut the Prius down .Its not the spinning down the charge I know what that is it happens in the winter all the time.

 

The reason I let it keep going that long is to see if it would stop on its own In that time the battery went down some but not much. I took it to Toyota and guess what they said We cant see any problem. The prius never has done it again. So if this never happened to you I don't think you can comment what was happing to my Prius

 

Is it possible this situation happens only when the battery is highly charged and the motor is undertemp? This is a obviously little different that the descriptions I have heard so far, but is it possible the charge on the battery is causing the engine to shut down (to avoid further charging), and the under temp motor is asking the engine to start back up?

 

Someone told me about on off cycling on their car It happened in the summer and in a flat area so no way it needed to dump battery charge. They were sitting in a traffic jam.

My car has never done this so far.

I have seen battery equalizing that seemed pretty strange till I learned what it was. Maybe this was another form of battery cell equalizing than what my car did?

Or could it have to do with a cannister purge cycle? I don't know how that works yet.

 

The engine isn't actually cycling on & off as y'all led me to believe.

I hunted out a hill in the suburbs that would allow me to glide the entire way down and was long enough to generate a substantial electricity reserve . And by an amazing stroke of luck, I actually did. Every light in the series was green. The one at the bottom was red. The moment I reached it, the eighth bar illuminated in green. Stopped there waiting for traffic to open up, I felt (for the first time ever, despite almost 105,000 miles of Prius driving) that "discharge scenario" begin. It was most definitely doing that to protect the battery-pack.

But it wasn't utilizing any fuel, hence no "on" (start).

The engine motion was far too smooth for that. It didn't take long to figure out what it was really doing. The small motor was spinning up the engine to full RPM for starting, then allowing it to slow down almost completely... repeating the process over and over again, draining a little bit more of the electricity supply each time.

There is no actually starting & stopping of the engine. It only spins via electricity.

 

suppose a prius-tech-in-training's opinion won't convince everyone here... but last night as we were checking out this thread DH told me that you guys had come up with the answer, that it's just the bleeding off of electricity from the battery and any shop will tell you there's nothing wrong with the car.

take it or leave it, just adding my 2 cents.

 

uh.

see my last post- right before yours.

 

No. no, no. Her DH is the tech. Galaxee is a pharmacology Ph.D. student.

 

my husband is an ASE-certified (should hear about that master cert in a week or so), toyota tech. he's in training to be a prius tech. well, you could say he's apprenticing with a certified prius tech but he works pretty independently on prii daily now and has had ZERO prius comebacks in the 6 months he's been working on them. all the prius techs go to him for basic operating knowledge that they don't have because they don't drive prii themselves.

we have an 05 black since march, he drives it regularly but not as often as i do.

now that you've got his credentials... and he's had time to mull over the problem a bit and check out the thread in very good detail instead of glancing over it... here's his 'final answer'

yes, it's normal. nothing is wrong with the car. it's trying to maintain the optimum engine temp to keep fuel efficiency high and emissions low. it's more economical to have it start and stop rather than just stay on.

as some pointed out here, it may also be related to high soc on the battery, IF the battery was green when it happened. what john saw was because he was coasting downhill and the battery was being charged too much, so it was spinning up the motor and not actually starting it, to bleed off energy.

also, it's not related to canister purge cycles (only done when the ice first starts) might be done sporadically as the motor starts and stops, but wouldn't cause the on/off/on/off cycle like that.

[editorial note: i'm just typing what he's telling me. i have no personal knowledge of this stuff]

a more detailed explanation of what happened would be good too, some in-depth details. how long was the engine on and off for? how long was the car on? how long was the light? how many bars on the battery? etc.

either way though, the car's fine.

 

Thanks, Evan, for your forthrightness and research. My car has cycled, in both warm and chilly weather, based on SOC. From the sound, I always thought the ICE was coming on; thanks for your confirmation. And thank you, Wayne Brown.

It is disconcerting when this very smart car starts turning on and off, seemingly for no reason. Now we know some reasons.