ok so after driving around tonight in the snow when I'd brake hard I notice the brake pedal popping back at me... is that normal?

~wC

 

The xB is even more sophisticated we think , here's an excerpt covering the Safety Systems from the the 2005 product intro:

VII. SAFETY SYSTEMS

A. Brakes, mechanical
1. 10.0’’ (255 mm) ventilated front rotors with 2-piston calipers
a. carbon fiber pads
b. rotors are 0.9’’ (22 mm) thick vs. 0.8’’ (20 mm) thick for ist, bB, and Echo
c. rotor side thickness = 8 mm vs. 6 mm
1) longer rotor life
2) dissipates more heat from long high-speed stops
2. 8’’ (200 mm) drum brakes at the rear

B. Brake Control Systems
1. xA has standard 4-wheel ABS; ABS ECU integrated with actuator
2. xB standard w/ ABS and VSC+TRAC
3. new ABS or VSC+TRAC actuators with integrated ECU
a. made by new supplier ADVICS;
1) joint venture formed by TMC, Denso, Aisin and Sumitomo Electric 2) 90% of sales to Toyota; 10% to other OEMs
4. Standard Brake Control Functions
5. Anti-lock Brake System
a. maintains steering capability
b. during braking at the threshold of traction

C. Electronic Brake-force Distribution (EBD)
1. dynamic adjustment of braking force at each wheel
2. transfers braking front-to-rear or side-to-side
3. works by measuring minute amounts of wheel slip under braking to balance individual wheel cylinder pressures to available traction
4. eliminates mechanical F-R proportioning valve (P-valve)

D. Brake Assist
1. on xB model only
2. via ABS/VSC actuator
a. pressure sensor on master cylinder detects “panic” brake application by signature rise rate.
b. if driver does not continue to apply sufficient pedal pressure for panic stop, additional pressure provided to calipers and wheel cylinders by VSC pump

E. VSC + TRAC
1. std on xB
2. TRAC limits wheelspin when accelerating on slippery surfaces
a. to preserve steering control
b. 2-way communication between the Skid Control ECU and the ECM
1) individual cylinders, up to 3 cylinders, are shut off to
reduce engine output to match available traction
2) brakes of individual wheels applied to reduce slip:
transfers torque across to the other driven wheel
3. VSC detects and counters early onset oversteer or understeer
a. by cutting off fuel to 1 to 3 cylinders and
b. applying brakes at individual wheels to counter yaw moment
4. wheelspin is detected by individual wheel speed sensors
5. incipient understeer or oversteer detected by central yawrate sensor
6. New design ABS/VSC actuator
a. Rotary gear pump rather than 2-piston pump
b. Quieter, smoother operation

 

The pedal "pop" or "pulsing" is the anti-lock brake system automaticly "pumping the brakes" for you to prevent the wheels from locking up.
Now all you gotta do is "stomp & steer"

 

Thanks for the great info!
Can you *please* post the links for the source
and do they have data for the 2004?

Thanks!
:D

 

the specs should be the same....

~wC

 

In fact that was from the 2004 Product Introduction, I didn't notice that initially. I tried to find the web site again where it was posted but I am unable to pull it up in Google. It was an Toyota press release site for the media. Luckily I downloaded the document when I found it, it's a 32 page pdf file covering the xA & xB in greater detail then I've seen anywhere. PM me with your email address and I'll send it to you.

 

I had the opportunity to drive '05 xB in some snow this weekend. Lost Canyon Camp @ Williams, AZ had about 5-6 inches of snow. (with a little ice underneath).

With stock suspension, engine, factory alloy wheels and tires, I had absolutely no problems. It was very sure footed. Funny to see a big Yukon fishtaling while the little xBox just moved forward.

That's the 2nd big SUV in a week that I've seen with 2WD. Why anyone would buy a behemoth SUV with only 2WD is beyond my ability to comprehend. They pay a premium for the vehicle itself, pay another premium at the gas pump due to poor gas mileage, and then at the time they could REALLY use an SUV, they can't because it is only rear 2WD.

 

its really good. ive been stuck maybe like 2 times in over a foot of snow. for a max of 5 mins. im not worried when i drive my car in the snow, only thing i am worried about it someone else losing control