GreenHybrid - Hybrid Cars - View Single Post - Prius FAQ: Snow and Ice vs Traction Control

Tideland Prius · #6 (**permalink**) 04-07-2008, 11:17 AM

I seem to be the only person that had experiences with both TRAC setups on the same car.

Here's the background info in case you haven't been following me on PriusChat:

2005 Prius bought in Oct 04.

The first winter, I got stuck pulling out of the curb. We had a good 10-15cm of snow. I decided to test the Prius' TRAC since it's the first winter and snow events around here (esp. with 10+cm) are few and far between (they usually melt within days). As expected (at the time), the wheels spun and the TRAC cut all power. No amount of prodding on the acccelerator would produce any forward movement at all (can't imagine rolling on momentum if the power was cut while making a left turn).

Anyway.. that was my one and only time with the TRAC cutting all power. Next year (winter 05/06), there was that ECU update. My Prius tech fried my engine ECU so my poor car was at the dealership for a week and a bit.

I found out the TRAC changed its behaviour by accident actually. I was backing into the garage (we're on a slope) and I noticed this weird sound... it was like the engine was revving up and down. I thought it was weird but figured it was the TRAC doing its thing. Then I noticed the blinking Slip Indicator. Ok, so it was TRAC. I had regained grip by then so I ignored it. I knew it was a bit icy in the alley. So I continued to back up and then it happened again. It was then it strucked me. The tyres were spinning! I stopped the car then intentionally tried to get the wheels to spin and it did. The engine was just revving up and down as the power was fed in pulses by the TRAC in an attempt to regain traction.

I posted my findings online and we couldn't figure out why I had the old "cut all power" TRAC behaviour before and now it was exhibiting the "slip and grip" behaviour. I thought it might have something to do with the ECU update but a wife of a Prius tech said her DH wasn't aware of any changes done to the TRAC.

I hope you can delve deep into this issue and maybe find out how I managed to get it changed and help those that have the old TRAC setup, update to the new one.