https://www.clublexus.com/forums/gx-...l#post10465066


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Acrad - thanks for this!

 

I imagine that this value should not be zero sitting flat and not moving?

I can get the pressure value to change while turning and driving.

 

I would think so but haven't dug into this system much from a troubleshooting perspective.... here is some more info related to the 1851 code

 

I can hear the up/down solenoids click, so probably not those. Throwing in the towel here and taking her to the local Lexus dealer later this week. Will let folks know what they say.

 

UPDATE (hopefully final):

The dealership drained and repressurized the KDSS system. No new parts. Everything seems to be in working order now. I moved the air suspension sensor mentioned above back to factory settings as the lean also appears to be corrected after the KDSS refresh. I fired up the techstream application and I can see that while idling there is about 2.2mpa pressure at 32F - seems about right.

The only remaining question is where did the KDSS oil go? I purchased this vehicle used maybe about 6 months ago and noticed rust in all the usual places - which is common for the Midwest - but perhaps it was worse than I thought and there might be a leak somewhere on one of the lines or the rams. The Lexus tech couldn't find anything obvious once the system was fully pressurized but I guess we will find out over time. I immediately applied Fluid Film to the underside after I purchased the car so that also makes it difficult to see any leaks as the whole underside is greasy.

The car handles significantly better now. It's also nicer going over bumps and such. A noticeable difference for sure.

One final note for others, the dealership I went to did say that they only very rarely see a GX car come in with a KDSS issue and the Service Rep hasn't even seen one himself before. There was only one tech at the dealership who has ever even worked on the system. All this to say is that KDSS issues seem to be quite rare in the wild, despite a number of posts about it. That being said, I bought this car for its reliability and range of use, so it did peev me a bit to have something completely unheard of (at least to me) at the time of purchase go out, but so far so good.

Thanks to Acrad for all the useful information added here. It will definitely help anyone else who has this issue.

 

What dealer did you take it to?

 

Hello everyone, i just changed the suspension on my 2014 gx460 from 2020 and the kdss system is not functioning. Who dealt with this issue, where, how and from whom did you repair this system?

 

You are going to have to provide a lot more details before you get intelligent answers.

 

Based on the diagram of the kdss, it seems that the front and rear shock cylinders are always connected and can move fluid regardless of the solenoid valves being open or closed. It seems at less then 12mph or with a bypass switch you are opening valves and connecting the accumulators which is what is really giving the comfort feel. Almost like a disconnect between the front and rear cylinders because now you have a gas piston buffering between front and rear.
Is my explanation a correct understanding of the system?

 

usually only dealers have the KDSS service tool to be able to bleed and fill the system. some independent shops have them sometimes but you need to call and make sure, make sure they actually tell you they have the tool.

 

No. The KDSS cylinders are not "connected", i.e. able to pass fluid when KDSS is disabled. When enabled, the fluid path is opened between the cylinders. The logic is based on speed, accelometer input and yaw.

 

Dr KDSS can give you suggestions if you want to take this on as a DIY project. There is a lot of information in the service manual as well.

https://drkdss.com/en-ca

 

This was my understanding as well, I only questioned it because the schematics posted by Acrad in this thread, showed that the 2 valves that close of the system were shown not actually between the front and rear cylinders but just blocking the 2 accumulators. Then KDSS is great for crawl speed only, above 12mph you will have a very stiff ride and that is the tradeoff unless going with the KDSS bypass. Thanks for the info

 

This info is from the FSM

https://www.clublexus.com/forums/gx-...l#post10526798