Can someone explain how the TRAC traction control system works?

[snipepod]

I've asked many Toyota salesmen, and this question always seems to be over their heads.

I am considering purchasing a Matrix or Xd Scion. I live a steep driveway and live in snow country. My other cars are front wheel drive with open diffs (spider gears). When the driveway is slippery, the cars stall out, and one wheel (the one without traction) just spins, while the other does nothing.

Does the TRAC system have the brains to apply braking forces to the spinning wheel, and transfer torque to the other wheel (like a limited slip differiental)?

Or is the Trac system just a system where in drops engine rpm to prevent the one wheel from spinning. (Which is useless in my situation)?

[toyotechwv]

Originally Posted by snipepod

Does the TRAC system have the brains to apply braking forces to the spinning wheel, and transfer torque to the other wheel (like a limited slip differiental)?

Or is the Trac system just a system where in drops engine rpm to prevent the one wheel from spinning. (Which is useless in my situation)?

It actually does both depending on the severity of the detected wheel spin.

[snipepod]

Thanks for the reply.

How can the TRAC system build hydraulic brake pressure at the spinning wheel if the driver does not have their foot on the brake pedal? Is there some type of electric servo and separate hydraulic circuit that is separate from the brake petal that has this ability?

[toyotechwv]

Originally Posted by snipepod

Thanks for the reply.

How can the TRAC system build hydraulic brake pressure at the spinning wheel if the driver does not have their foot on the brake pedal? Is there some type of electric servo and separate hydraulic circuit that is separate from the brake petal that has this ability?

It uses the ABS actuator.

[snipepod]

Could you go a little deeper into how the ABS actuator works? How does it build hydraulic pressure? I understand how the ABS uses either an optical or hall effect pickup at each wheel to detect wheel RPM and feeds it into the ECU (computer). What I don't get is how the hydraulic pressure is created to apply braking pressure to the low traction wheel.

[toyotechwv]

Originally Posted by snipepod

Could you go a little deeper into how the ABS actuator works? How does it build hydraulic pressure? I understand how the ABS uses either an optical or hall effect pickup at each wheel to detect wheel RPM and feeds it into the ECU (computer). What I don't get is how the hydraulic pressure is created to apply braking pressure to the low traction wheel.

If you have Adobe Reader I can try to email you a diagram and full description.

[jet2757]

I would love to see the diagram.

[toyotechwv]

Originally Posted by jet2757

I would love to see the diagram.

I can email it to you.