can you disable the tration controll?

Fair enough.

Tom

 

I've always heard that disabling the TC will endanger the transaxle, but I'm still not sure why.

So far the only convincing argument I've heard is that if the car was allowed to rev high during a slip event, then suddenly caught traction, the final drive chain in the transaxle could fail.

For those that don't know, there is a chain which couples the output of MG2 and the PSD to the differential. Supposedly if you were spinning the wheels, MG2 would of course be at high RPM. It's rotor has significant mass, along with the other components in the PSD, so supposedly a sudden grip when you find a dry spot could result in high dynamic loading of this chain and thus failure.

It makes sense, but since I don't have the numbers on these components, there is no way to do calculations to determine what kind of stresses they are talking about. I'd also have to know the capability and/or maximum loading capability of the chain without failure.

The other issue, even if this proved to be a non-issue would be how to disable the thing without affecting the other systems that the braking ECU controls. You'll lose regen right off the bat. Inspection mode leaves the engine running. The compromises would not be worth it.

 

Other possible conjectures include MG1 over-speed and high dv/dt in the motor coils.

Tom

 

This is over-RPM. The HV ECU controls both MG's tightly and will not allow this. It has highly accurate Sine/Cosine resolvers that not only know the instantaneous RPM but also the angle of the MG shafts.

If you kept the MG's below safe limits, you could still spin the wheels at say 30mph without any over RPM risk.

 

Exactly, which is how controlled slip traction control works with diesel locomotives.

The question with the Prius is the transient response of the control system. Even with perfect resolvers, is the control system able to compensate for an infinite step function change in traction, and can it do it without damage?

Tom

 

40% incline??? I wouldn't even take a dedicated 4 x 4 on that much incline.

Dbcassidy

 

Does anyone know if this procedure will work on a 2012 ?

 

This procedure is not working on my 2012. It will not go
into Neutral. Does anyone know anything about this ??

 

This is a GenII thread. I think someone posted different instructions for the newer cars, but you will need to search the GenIII forums.

 

You need to press the brake pedal in order to shift into neutral. I figured this out by watching a youtube video of someone demonstrating the procedure on a Camry Hybrid.

I just tested this on my 2007 Prius and it works.

My edit is a little awkward, but 4th step should read something like:
*Press and hold brake pedal, select "N", release brake pedal, fully depress the gas pedal two times.

Here's an emended procedure:

== Disabling Traction Control ==
'''WARNING: The shop manual apparently states in no uncertain terms that this procedure must NOT be used to drive the car as damage to the transmission could occur due to traction control being defeated.'''
* Follow the sequence below (quickly - within 60 seconds)
* Set Ign switch to ON, not READY (Power button twice, no brake)
* While still in "P" fully depress the gas pedal two times.
* Press and hold brake pedal, select "N", release brake pedal, fully depress the gas pedal two times.
* Select "P" fully depress the gas pedal two times.
(LCD display will indicate a !Car! in upper left corner of screen)
* Turn key directly to "start" to start the engine (brake+start button)

 

Thanks for this info

 

This is old info, 2nd gen. In your Owner's Manual:

 

Having a button on the dash infers it's ok for use when driving. With the older gen's, with the disable process only in the Service Manual, with a stern warning against driving in that state, I wouldn't do it.

 

Are you sure that that is from a Gen 2 manual? The copy of mine has no such entry, and neither is my car fitted with that button.

 

No, 4th Gen info. I was responding to a 4th Gen owner.

My wording was confusing though, sorry.

 

It is for this very reason that people should post in the correct forum. I didn't even notice on this occasion.

I don't know why it is happening, but it seems every Gen 2 post is jumped on by Gen 4 people.