My guess is that that hybrid battery became so drained that the ECU decided to not use it anymore. This can happen suddenly and will feel like the car loses power. It really doesn't lose all power, just the power from the electric motor. You should still be able to make it up any reasonable hill on just the ICE, just not as fast.

I think the reason your battery was so drained was due to A/C usage in a very warm climate. My battery drains very quickly when I first start out on a hot day while the A/C goes to MAX. After a while, the battery charges up and all is well. In my case, I think the only thing that happens is my mileage goes down in that time period.

Does this sound like it might be what happened?

 

This could be the problem, in which case it is really not a problem. The hesitation is a "lurching" sort of feel, in other words it happens several times in quick succession. I am going to try that same route tonight with a careful eye on guages an screen. Thanks for the reply. I will have to take the car to the dealership (which is an hour and a half away) if I can't figure this out!

tom

 

All Prius (including classic) have Traction control to protect the PSD, so I suspect that's your problem. What some vehicles don't have and what you are probably thinking of is Vehicle Stability control (VSC). The former prevents the wheels from slipping and losing traction when trying to apply power to the ground, the latter prevents you from fishtailing by appropriately applying brake power to individual wheels, and possibly control steering.

The former and the latter will be indicated by a flashing car with squiggly line under it, but VSC will also sound a buzzer (or chime/beep). If TC is brief enough, you might not get to see an indicator.

OEM tires are prone to trigger TC. I often get this with sandy or gravel surfaces, or uneven surfaces, such as transitioning to a recently paved surface from an older paved surface while accelerating.

 

Thanks Dan. You are right about the traction control, and that is what it feels like. I have replaced the tires with Comfortreads, however. It has done this before on wet roads going uphill, but never on dry roads. It does feel the same, though, now that you mention it.

Thanks,

Tom

 

My bet is it is not the TC problem.
I believe it is caused by low battery level and initial warming up period.
During the initial warming up period, ICE power is not used and it is just in EV mode.
Do you know why the battery level is so low?

Ken@Japan

 

Our 05 with 15,000 miles has had a very strange thing happen a few times. When we leave our house by acertain route, we go up a fairly steep incline at low speed. Recently, the car has hesitated like it was losing all power. Road conditions are dry, we don't have traction control (we have package 5).

Actually, all NHW20 Prius have traction control standard. You might be confusing it with the VSC option. (NHW11 Prius have a simulated traction control.)

If the road is a bit slippery (wet/icy, loose dirt or gravel under the wheels, wet grass/leaves, etc.), you will get a hesitation as the traction control reduces power to the wheels until all the wheels are going the same speed again. most commonly seen when accelerating from a stop onto a busy road (usually on a turn), or when going up a snowy/wet incline.

 

Do you know why the battery level is so low?

Arizona is a pretty warm climate. I frequently drop 3 to 5 bars from my initial state while sitting at the first stop light leaving work on warm afternoons. And I live in northern California, which is not nearly as hot on average. The A/C seems to use it up very quickly when it is in max mode.

 

The A/C seems to use it up very quickly when it is in max mode.

I understand.
Do you think my assumption, low battery level and initial warming up period, is the right cause?

If yes, try following.
Press START, switch to Energy screen, watch the energy flow and listen the engine noise.
After exact 56 seconds later form the engine start, you'll see the energy flow stopping and the engine noise changing.
If the battery level is one or two bars, try following.
Apply your parking brake, press and hold your foot brake, put in D then press accelerator pedal carefully.
The engine starts for charging, then keep accelerator pedal until battery level becomes three or four.

Ken@Japan

 

I think that the problem is probably caused by a low state of charge. We live in very mountainous terrain, and around town trips are generally very short. Our weather has been hot and dry lately, and the ac has been in constant use. My wife did note only one bar when this happened. I have tried the same route with 3 or 4 bars showing, and no problem.
Thanks for all the input. I feel better now.

Tom