I was in Seattle, WA over the weekend going to the Dead Sea Scrolls exhibit. When I was done, I left to hop back on the freeway. Traffic on the surface streets was heavy and I took a street (I think Denny way) that led up to the freeway. Right before the entrance, I climbed a fairly steep hill and due to traffic, I was stopped halfway up.

When the traffic started moving again, I let my foot off the brake and quickly stepped on the gas due to the minor rollback and the fact that the jerk behind me stopped rather close to me. That was when it happened. My TCH went just a little forward, felt like 2 inches or so and then rocked backward the same distance and continued to rock forward and backward. The ICE was on and I could see the electric motor assisting, but I wasn't moving forward! I kept pushing farther and further down the accelrator and nothing was happening.. still rocking back and forth. It wasn't until I was literally "pedal to the metal" when the TCH finally starting moving forward. It didn't "peel out" or lunged forward, it just moved as if accelerating normally.

After moving about 5-10feet, traffic came to stop again and I was still on an incline. I "hung" for a little bit for fear of it happening again, but resorted to the brakes when there was no immediate signs of traffic moving. When traffic moved again, I did the same process, but this time the car acted as any normal car would and moved forward.

It only happened that one instance, but it did freak me out.

 

I had something similar happen to me this morning at a stop sign going up a fairly steep hill. There were a lot of leaves underneath my tires, so I thought maybe there was a lack of traction. I don't know if I went forward and back, but I definitely had a hard time getting started. After I pressed harder on the accelerator (maybe 3/4 of the way down) the car proceeded normally. I've stopped at the same place maybe 50 times and never had it happen before.

 

I had a BMW that would do this on snow or ice or slick rain surface. It was in the traction control and you could floor board it and the traction control would tell the computer to retard the timing drastically and floorboarded it barely moved until traction improved. I would bet this has a similuar system. Another guess would be they may use an angle sensor telling the conputer you are on a steep hill, my understanding the TCH is not supposed to roll backwards on hill with foot off the brake.

 

It might be in the programing of the fly-by-wire system, and the sudden imput is being read as an anomoly. Slower more deliberate moments of the acclerator pedel might prevent this from happening.

 

could it be the transmission starving for oil?

 

Nope. Doesn't have that kind of transmission eg. NO torque converter but more like a differential in reverse. Sort of. It's a PSD (Power Split Device) and actually can't "slip".
I vote for the steep incline "confusing" the VSC system somehow.
On a side note my Prius (and current gen Priuses but have not tried it with my TCH) can exhibit a similar behavior on a steep incline with loose gravel. If the front wheels begin to slip the VSC reduces power to the wheels. If the wheels continue to slip it reduces power more. Right down to ZERO power to the front wheels and even with the "pedal to the metal" you go nowhere and the wheels won't turn.

 

Geckoboy,

Was the VDIM/TCS light on or blinking while this was happening? It is near/under the fuel gauge....

 

I dont believe it turned on/blinked. I was looking at the dash when it was happening to see if any errors or warnings showed up but there were none.

This only happened once on the hill.

 

Ok, so this weekend I went to downtown Seattle to check out the olympic sculpture park. On the way home, I drove up a steep hill (either Seneca or Spring) to hop on the 5 southbound. I came to a complete stop in the middle of the hill. The ICE was off. When it was time to move forward, I put my foot off the brake and stepped on the gas/accelerator. The ICE kicked on, my the car started to rock again! By rocking I mean it moved forward about an inch or 2, then moved backward the same distance, over and over again. It was like if the car attempted to move forward, then gave up (which resulted in going backwards), then tried moving forward again, then giving up.. etc..

The VDIM/traction light did not turn on. Streets were dry, weather was beautiful.

All I did to move forward again was to release the gas pedal and step it on firmly again. There was someone behind me so the time between when I fully released the gas pedal and when I stepped on it again was a second or slightly shorter.

On the next hill on which I was stopped in the middle again, the ICE stayed on and it did not happen again.

 

Strange! Thanks for the report, I will keep an eye out for this.