Activating KDSS

[jreiter]

After playing at the dunes this weekend I'm wondering about KDSS. Specifically, how do you activate it? More precisely, how do you free up the swaybars for off-roading? I've been checking through the manual and digging around on this site, but I haven't found anything conclusive yet. I know what KDSS does, but I just don't know how you *control* it. (If you even control it at all.)

I ask because while I was at the dunes I was initially using the Multi-Terrain Select (MTS) in sand mode. I had always assumed that activating MTS also activated KDSS and freed up the swaybars, since you only use MTS for off-roading/snow/mud/etc, and you generally don't want swaybars in those situations.

After messing with all the features throughout the day, I found that I had a whole lot more fun running around in the sand with all the gadgets turned off, including TRAC, VSC, and MTS. However, with all those features turned off, does KDSS have the swaybars freed up or not? There is no separate KDSS control, so I'm guessing either MTS controls it, or the computer is somehow always watching things and controls KDSS independently.

Can anyone help me with my conundrum?

 

[SeattleMike]

After playing at the dunes this weekend I'm wondering about KDSS. Specifically, how do you activate it? More precisely, how do you free up the swaybars for off-roading? I've been checking through the manual and digging around on this site, but I haven't found anything conclusive yet. I know what KDSS does, but I just don't know how you *control* it. (If you even control it at all.)

Can anyone help me with my conundrum?

It's completely passive. When one wheel goes up enough, and the other goes down enough as determined by the hydraulic sensors, the system simply disengages the sway bar. You have no control over it other than deciding where to drive.

 

[4RBob]

It's completely passive. When one wheel goes up enough, and the other goes down enough as determined by the hydraulic sensors, the system simply disengages the sway bar. You have no control over it other than deciding where to drive.

it's not speed sensitive?

 

[jreiter]

It's completely passive. When one wheel goes up enough, and the other goes down enough as determined by the hydraulic sensors, the system simply disengages the sway bar. You have no control over it other than deciding where to drive.

Okay, that's what I figured was happening. That's actually good, since I find that running around on the sand with all the traction control goodies disabled is a lot more fun. I just wanted to make sure I wasn't forcing the swaybars to be active the whole time by turning off Multi-Terrain Select.

 

[SeattleMike]

it's not speed sensitive?

Not that I am aware of... however, if you have that much wheel articulation at high speeds KDSS will be the least of your concerns.

 

[cucumber pie]

Try watching this video it should help explain how it works
The vehicle in the video is a landcruiser prado with KDSS
YouTube - Toyota Land Cruiser 150 - KDSS (Kinetic Dynamic Suspension System)

Hope the link works I sent it with my IPhone

 

[jreiter]

That is a great video you linked. It clearly shows how KDSS can work as a passive system with no computer or electronics involved. Thanks!

 

[lowrange44]

it's not speed sensitive?

I believe it is speed sensitive. According to the service manual, the KDSS system is tied into the vehicle speed sensor, wheel speed sensors, steering position sensor and if memory serves me, VSC and maybe something else...

I'll have to look up the page number in the service manual, but I was surprised to see how many systems KDSS ties into.

I'm pretty sure KDSS uses input from all those systems as well as hydraulic pressure sensors to determine how much sway bar flex to allow.

Somebody also mentioned that KDSS really restricts sway bar movement over 45mph. I don't have any proof on that though.

 

[Quentin]

That is a great video you linked. It clearly shows how KDSS can work as a passive system with no computer or electronics involved. Thanks!

There actually is an ECU for the KDDS. :lol:

 

[jreiter]

There actually is an ECU for the KDDS. :lol:

Doh, so much for it being a passive hydraulic system. I don't really mind as long as it is works regardless of the Multi-Terrain Select and TRAC/VSC settings.

 

[4RBob]

Doh, so much for it being a passive hydraulic system. I don't really mind as long as it is works regardless of the Multi-Terrain Select and TRAC/VSC settings.

XREAS is more of a simple hydraulic system.

 

[bluebaron]

I just came back from a two day trip down the Mojave Road in California. The car really leaned over on uneven trails. It appeared to me that KDSS really wasn't releasing the sway bars (hydraulic pressure). I have the Toytec ultimate lift and this was my first trip after installing.

Is there any sort of test I could perform?

 

[MrGrimm]

Does the KDSS light come on in the dash when it engages? I see it every time I turn on the vehicle but I haven't seen it turn on when I am on the trails.

 

[bluebaron]

Does the KDSS light come on in the dash when it engages? I see it every time I turn on the vehicle but I haven't seen it turn on when I am on the trails.

I believe it only comes on if there is a fault.

 

[SeattleMike]

I just came back from a two day trip down the Mojave Road in California. The car really leaned over on uneven trails. It appeared to me that KDSS really wasn't releasing the sway bars (hydraulic pressure). I have the Toytec ultimate lift and this was my first trip after installing.

Is there any sort of test I could perform?

Find a ramp, see if the swaybars disconnect?

 

[Ryan_S]

Find a ramp, see if the swaybars disconnect?

The sway bars do not "disconnect" as such. The hydraulic cylinder replaces one of the sway bar mounts to the frame, by changing the pressure there it changes the stiffness of the bar. You would be able to see the cylinder extend of you put the right side of the vehicle up.

 

[bluebaron]

The sway bars do not "disconnect" as such. The hydraulic cylinder replaces one of the sway bar mounts to the frame, by changing the pressure there it changes the stiffness of the bar. You would be able to see the cylinder extend of you put the right side of the vehicle up.

Would I have to have the engine running?

 

[bluebaron]

OK....been doing a lot of testing and here's where I am. I zeroed KDSS and also released the KDSS accumulator just to be sure there was nothing wrong. No error codes.

Went out on a test drive on some rough ground and found the rear KDSS works perfectly. The front piston never compresses effectively leaving the sway bar at it's stiffest setting at all times. Could I have damaged this in the lift? I had to jack the sway bar back in place.

Any ideas?

 

[jreiter]

Went out on a test drive on some rough ground and found the rear KDSS works perfectly. The front piston never compresses effectively leaving the sway bar at it's stiffest setting at all times. Could I have damaged this in the lift? I had to jack the sway bar back in place.
Any ideas?

This is interesting. Have you tried driving one front wheel up onto a ramp? If KDSS is working, that one wheel should go up the ramp while leave the other wheel on the ground, and you should see the piston compress. If it's not doing that, then it's possible something is wrong. Definitely keep us updated if you find anything out.

 

[iDRiVaT4R]

I used a floor jack to compress my front KDSS piston when I did my lift install, and it still performed ok off road.

If you have 2 car ramps, decent height ones, stick one under the front drivers wheel, and one at the rear passenger wheel and drive up onto them. the front piston should compress, and the rear should extend.