Hill Start Assist & Shifter Problem

I tend to have a heavy foot on the brake when stopped which activaes the Hill Start Assist.

This morning during my normal commute I notice the HSA doesn't engage every time the brake pedal is pushed to the floor, perahps 1/3 to 1/2 the time it doesn't engage.

At 8:00 the car is parked in Ready mode with the doors locked manually and the fob in my pocket. Everything appears normal until I fully depress the brake & try to shift into reverse. The shift knob won't move as if locked in place. B, D, R, N makes no difference.

Over the next 30 minutes or so I try powering down & restarting several times. Again, everything looks normal. No extra idiot lights or unusual beeps. After about the fifth or sixth time the brake pedal acts differently. First, spongy as if there wasn't any brake fluid and it goes to floor very easily. I let up on the pedal and the next stroke is very hard like applying power brakes without power and with some resistance to the shift knob I get into Reverse. I back out of the space and can drive normally and have standard braking ability. I call Cherry Hill Toyota to tell them I'm on my way in.

Over the 35+ mile ride the car handles like nothing happened. Most of the times stopped at traffic lights the HSA engages. Some times it did not. Once in Burlington City and most notably at the 2 traffic lights just before the dealer and again on their lot in front of the garage door.

My ScanGauge II did not find any codes. OAT was high 30's F, about what we experienced the last few weeks, and it was foggy.

After having the car for ~ an hour I go on a test drive with the Tech so he can demonstrate that nothing is wrong. (During the ride the car performed normally.) I asked if he pulled any codes from the Brake ECU. His reply was there are 23 computers in the car and there weren't any codes in any of them. He said he'd contact Toyota & do some research as he hasn't heard of this situation before.

Any insight is greatly appreciated & will be shared with the dealer as I want to resolve this ASAP. Getting stuck by the office on a workday is one thing. Getting stuck elsewhere could be worse.

I put 1000-1100 miles on the car since I bought it a month ago.

Thanks for your help.

Jim.

 

Understood & no offense taken. I know why one has to ask: Is it plugged in? Is it turned on?

I would be thrilled to death if this is just an ID10T problem and would leave it at that if this was the 1st day or trip. I'm not claiming to be a G3 expert but it seems that if this is just "technique" it should have happened sooner. "Brake firmly engaged" is a tough habit to break overnight.

Unfamiliarity with the car was an issue on "day 0". Not knowing about HSA during the test drive I remarked about the VSC icon while at a dead stop. Salesman couldn't explain it. Another explanation was that some very small amount of wheel slippage was detected which tripped the light. My reply was, "NOT at a dead stop. If wheel slippage is detected then something's wrong." I realized it was the HSA reading the 2010 "problem" thread.

(Cherry Hill Toyota is owned by Holman which owns many dealerships. Three of them are/were Saturn lots. I got the impression that the displaced Saturn employees transferred to the Toyota lot.)

 

I'm the only driver so if something fell into the shifter it would have happened in the first 100+ miles while in the dealer's inventory. He did ask if anything went down the shifter. At this point I don't believe I want an exploratory just to see what's in there. If the thing fell into an empty space where it won't cause anymore problems is that good enough for me?

"So you come to a stop and then keep applying heavy pressure and the pedal goes to the floor or does it seem to be limp under your foot and go to the floor after a little while on its own?"

The "limp" & "stiff" pedal happened only once--when stuck in the lot just before I was able to shift. As I recall, the pedal went limp. I released the pedal and the next stroke was "stiff". I'm not sure I even pushed the pedal all the way to the floor. Normal feel after that. I don't ever remember hearing or feeling a click when HSA engages. I will pay more attention tomorrow.

When the brakes were lightly applied (just holding the car stopped) the Gen2 drew current from the traction battery which didn't happen when the pedal was pressed harder.

"Did the tech check the fluids and pressures (and sensors) in the braking system?" Apparantly he did not as it is not noted in the on-line service record. Since I have his e-mail address I'll ask.

Here's the latest update from the Shop Foreman:

"I called my engineer group in regards the shifter issue in your Prius. They have no issues where the shifter would not move.
I mentioned about the Scan Gauge that you have installed, they stated it could possibly be a problem but not likely.
They asked to have you monitor the issue as to temperature, brake on or off, ready light, check engine light and or triangle with exclamation point.
Please keep me informed."

 

Yes, HSA is Hill Start Assist and the pedal has to be pushed almost to the floor to engage. It is standard so every II-V has it.

 

Thanks for the info & reassurance. I'll try to lighten up.

 

I was told the brake fluid, pressure & sensors were not checked as they would have thrown a code.

I needed to secure the slack in my ScanGauge cable so while I was down there with the car OFF I played around with the brake. Travel felt "normal" and I did hear it pump once about every stroke.