I'm looking if anyone's has had this issue. Specifically, when on regenerative braking from highway speed, having the car act like the transmission is about to drop out until you get to low speeds. Doesn't happen on acceleration .. and not very consistently. It had thrown a code about the O2 sensor going out of range, but that cleared after 3 restarts. This is a 2012 Prius (classic) model 3 with 190,000 miles on it.
I don't know, would seem to be more consistent and not throw an error code if it were the CV joints. I'll see if they're leaking
Be careful what you assume. The vanishing error code may NOT be associated with the other behavior at all; I think it probably isn't. Is this a noise or vibration......or both ? Does it do it when "coasting" or only when you lightly apply the brake ? Does it change if you brake fairly hard right at the beginning of decel ?? With 190K miles, it could be a lot of different things. Could even be badly worn brake pads or warped rotors. I think they start lightly applying even when the bulk of the decel is from regen. Edit: Could it be that the ABS is kicking in ? That makes a TERRIBLE noise.
This is when coasting // brakes not being applied. I just had front and rear brake pads changed and rotors resurfaced (190k miles on original -- yay). Makes a sound, but not exactly a vibration when its going kerchunk as if struggling. The problem went away when the check engine light went on, (with the light and code going away after a few power cycles). At 190k, I just wonder if its time to get another one. My first Prius lasted 245,000 miles before the engine oil burn got to much.
ABS on mine seems almost silent when it kicks in ... what I notice, if anything, is likely to be the tire-to-slidey-surface sounds. It doesn't sound anything like what I remember from the earliest ABS cars I encountered.
If it happens when coasting, then it doesn't sound like a brake issue. "Kerchunk" makes me wonder about slop somewhere in the drivetrain. But I would expect the to be felt as well as heard. (Head scratching emoticon here.) One thing I'm surprised none of us thought of is to ask how you obtained that O2 error code. Obviously, you're pretty familiar with the Prius, but we should not just assume that you know that most code readers are not Prius literate and will give bogus readings.
ODB2 bluetooth reader .. I know the values have to be interpreted differently than most cars because 'rpm drops to zero' isn't normal for most cars .. but I wouldn't think the actual scan codes would be that different. If I need to go get a CANBUS reader than I can.. On felt but not heard .. it made a sound, I just wouldn't call it a vibration.
My 2013 v 240,000 does something similar but never a code + I have Techstream.... and I have a new (70,000) mile trani in my garage.
Generic code readers do not have the proprietary Prius codes. Hybrids generate codes that non-hybrid-capable readers never dreamed of. LOTS of them.
The main thing is usually that the Prius has a bunch more computers in it than most scan tools even imagine asking for codes, and the usual result is people posting on PriusChat that they have warning lights on the dash and no relevant codes retrieved by their scanner. I agree that it's harder to explain retrieving codes that are bogus; it should not be that hard for any scan tool to decode a letter and four hex digits correctly when it receives them, whether or not it has any idea what the code means. And so that usually isn't what we're talking about when scan tool compatibility comes up, but I can't say never ... there really have been threads here where somebody will post a string of goofy-looking DTCs said by no Prius ever, and we sort of skip over trying to explain it (buggy scanner getting the message framing wrong, and decoding the wrong bits? who knows?) and go right to "try Techstream, it probably won't do that", because we figure getting the car fixed is the topic of greatest interest. If somebody wanted to send me a goofy-code-reading scan tool and a protocol analyzer, and clear my calendar and pay me to figure it out, probably I could eventually, but I haven't been finding any offers like that in my inbox.
During the life of the car, has the transaxle ever been serviced? The way you describe the noise, it sounds like you may have some problems in the drive gear system in the motor speed reduction section ( planetary ring and pinion). Perhaps a side bearing that has thrust against it on deceleration. If you have no history of the transmission being serviced I would suggest that you have it drained so that the oil can be inspected for metal particles.
Mine lurches once every morning in colder weather on cold soak start up. Parking brakes keeps it from really pulling forward from lurch.
