KDSS existing or new owners BEWARE!

Ignorant Post

 

That Aisin thing is the control unit / pressure sensor for the KDSS system.

My 78,000 km, 2010 4Runner Trail started displaying the KDSS warning light last week.

Turns out that the electrical connection from the harness to the Aisin thing had corroded and a few female pins from the harness side Those pins are are now permanent features of the connector on the Aisin.

The rest of the KDSS system is fine. No leaks, very little corrosion.

The "fix" requires - at minimum - a new accumulator assembly (incl. the pressure sensor).
And the system lines, a recharge and a calibration.

While it is possible to remove and replace the Aisin controller (IF it is separately available), there is no way to isolate or lock-out the pressurized side of the system from the Aisin bit.

Dealer quote to repair: $6000 Canadian (or thereabouts)

For what is essentially a corroded connector.

 

That sensor doesn't control anything. It just monitors the system for problems. The system operates by hydraulic pressure.

 

Great system, but bad design for sure. I wash mine out 1x year and spray it with fluid film. I’ll let you know in 10 years if this helps.

 

So no repair needed? The only issue is the warning light?

 

In the KDSS (Kinetic Dynamic Suspension System), a cylinder is installed to each of the front and rear stabilizer bars. The front and rear cylinder upper chambers and the front and rear lower chambers are each connected by a pipe. The hydraulic circuit is filled with high-pressure suspension fluid.

The stabilizer control ECU controls the stabilizer control solenoid valves according to input signals from sensor.

 

The relevant bits from the Service Manual:

http://www.to4runner.net/system_description-1160.html

 

My understanding is that KDSS is a completely passive system and the electronic part is just a sensor. I guess you could check to see if it's functioning properly and make your own decision from there.

I understand what KDSS is. I'm usually the one explaining it.

What I'm apparently not 100% sure on is what the accumulator actually does.

My understanding was that it allows the fluid to somehow flow freely so that the stabilizer bars can move independently as the vehicle goes over bumps in regular high speed driving.

Other than that, the hydraulic lines and pistons do their job passively.

 

The Service Manual implies otherwise.

DESCRIPTION
The stabilizer control ECU receives information from the steering angle sensor, skid control ECU (speed signal) and yaw rate and acceleration sensor via CAN communication. Based on this information, the stabilizer control ECU turns the stabilizer control solenoid valve (built into the stabilizer control with accumulator housing assembly) on or off.

DESCRIPTION
The stabilizer control ECU receives the speed signal from the skid control ECU via CAN communication.

DESCRIPTION
The stabilizer control ECU receives steering angle information from the steering angle sensor via CAN communication.

DESCRIPTION
The stabilizer control ECU receives forward, backward and lateral acceleration information from the yaw rate and acceleration sensor via CAN communication.

 

Well, that seems like a good reason to keep the accumulator clean.

It seems a little unnecessary, though, as the basic functions could be accomplished without electronic assistance.

Thanks for the information.

 

After cleaning my Accumulator thoroughly today at the pay 'n' spray, I see that I need to take much better care of it. I would always try to spray into the little skid, but I can see that hasn't been sufficient.



The hydraulic lines are beginning to corrode where they're attached to the accumulator. I'll have to clean them up, and I think I'll hose it down with fluid film as someone suggested earlier.

I strongly recommend that anyone who has KDSS spend some time every few months (at least) inspecting and cleaning the accumulator. It's probably the most expensive part to replace, and apparently it's also the most susceptible to failure.

 

Yup going to spray mine down tomorrow. Mine looks new but I’m going to get on top of this.

 

How many klicks on your truck? Do wade through watering holes often?

Seems like a lot of corrosion for a 2019.

 

Just about to hit 55K. Yes, water crossings, mud, snow, salt. I'll have to do some rust clean-up soon.

But, keep in mind, this accumulator had dirt built up in the skid for who knows how long. The rest of the truck is not as bad.

 

Just another thing to add to the maintenance list. I feel that there will be less KDSS failure when people start taking care of it.

 

Great point! It seems that the failures I've read about are largely due to corrosion. If people are aware and take care of it from the beginning, the majority of failures can be avoided.

 

Well this story just came full circle for me...
When we were looking into the 4Runner we asked around for friends and family who may own one for advice.
The single piece I received was from a friend whose in-laws owned a 4Runner limited (not the point but they have more money than cents... if you understand). Anyways, they said they loved it till "something" in the suspension went out & Toyota wanted a ton to R&R it.
2 yrs ago I kind of knew what they were talking about (KDSS) & we got ours without it. Another reason for keeping the '19 is less shit to break.
Long story short. IF you own a KDSS equipped 4Runner you must keep this part clean! Their 4Runner was driven & put away wet by rich people who garaged it nightly. Their own ignorance caused them to hate 4Runners so they bought a Lexus...
Dead serious!
Ryan
Edit for spelling only (likely missed something). Lol

 

Agreed but sort of sounds like the kind of stuff RAM truck owners say. I just expect better of Toyota, and having the baby some of these components kind of defeats a lot of the point of the T4R, idk.

 

If they have a Limited, they do not have KDSS. They have XREAS. It's another cool setup, but even more expensive to retain. KDSS is compatible with many aftermarket suspension options, while XREAS can only be lifted via spacers. It is easier to eliminate than KDSS, though.

I agree to an extent, but we're talking about removing 2 bolts periodically and spraying down the accumulator to prevent corrosion. It's going to add about 5-10 minutes to your post-wheeling clean up. It's not a matter of "babying" it, but a little extra maintenance.

Also, I've said numerous times that if you're into hardcore wheeling and significant suspension modifications (long travel, big lift, etc) that KDSS would be a waste of money for these types of people.

I will continue to say that it's excellent for weekend warriors like myself, as it still has real benefits over the standard sway bar setup. It just requires a little attention now and then.

 

You are 100% correct. I knew I had something wrong. Thanks for not hating on me! LMAO
I don't have either & no interest so I don't know what I don't know.
Still learning 2 yrs in.
Ryan.

 

Me, too! I keep finding out there's more to this than I had thought. I still think it's the bees' knees, but I can't blame anyone for wanting to go with a less complicated suspension. I still think it will hold up fine with some care. We'll see.

 

Hello James, I work on aircraft and am familiar with various aviation corrosion preventatives. I'm not sure I want to spend the $$$ for aviation grade corrosion preventative. I'm curious what you are referring to - what is "fluid film"?

 

https://rsgmetalworks.com/products/rsgt4r5kdskpc

 

It's a greasy coating that many people are using to prevent frame rust on their Tacomas.

That looks like better protection, but would still need to be removed and cleaned out periodically.

 

I believe it is Lanolin (a wax) not grease. Again, I could be wrong.
Ryan.

 

I think you are correct! I couldn't recall what it was.

 

I use the hell out of it for my salt spreader. It has one small chain would get rusty in a few storms. It also has a giant draglink that seizes in the summers. I have been using FF on it for a 1.5 years and the chain looks brand new while the draglink worked all the stiff points out of the links due to constant spraying. It has saved me a lot of time & frustration with a simple spray.
If you can't tell; I love it.
Ryan

 

I believe it is a fantastic product! I used it on my frame before I bolt it on the sliders.

 

Just to follow up on this and what @KLOC pointed out, there actually is active control of the KDSS system by the Stabilizer Control ECU. It controls and monitors the upper and lower shutter valves in the accumulator assembly based on various parameters. One parameter is whether the vehicle speed is above or below 12 MPH. So on pavement and at speed KDSS is engaged, valves are closed. Slow speed on surfaces where there are uneven forces between wheels the valves are open to allow the hydraulics to work and flex the suspension.

It’s important to pay attention to that electrical connector.