This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
The AHC system is pressurized, particularly when it's supporting the sprung mass of your vehicle; so short answer is yes you will need to replace a lot of fluid if you remove and replace your AHC shocks and bleed the system. But the real question is why would you do that? If it's to improve damping or ride then you're barking up the wrong tree as the AHC /AVS system is not a conventional shock damper suspension, the damping function happens at the four damping control valves with the round accumulators hanging off them. If your AHC shocks have failed and are leaking badly ie fluid dripping out, then you probably have bigger issues like contamination to address before deciding to throw money at AHC repairs. If you just want to rip out the AHC and install a conventional system then there are a bunch of posts on that.found them for the LC not not the LX Tho i searched .. But maybe i did not search hard enough sorry if that is the case. My primary question is does the ACH Fluid need to be drained to replace the shocks? also a DIY would be great if someone can link me to one.
When the AHC/AVS system has failed people report that the ride is horrible, bone jarring, pavement ripples and small bumps transferred to the cabin - you get the picture, so if you're not feeling this your system is probably ok. Before spending money on new accumulators you should baseline your system and changing the fluid out is a good first step. Now assuming your vehicle height and cross level is good you want to check and adjust neutral pressures; if that hasn't been done since delivery it's guaranteed your pressures will be high. You also want to check how many graduations the fluid level changes in the reservoir when you go from low to high, more than 7 is required. Also check the damping switch changes the ride quality when switched from position 1 through 4, it should go from smooth and a little town car like to quite stiff and firm. Take into account how worn all the bushings and rubber cushions are, tires and their pressure etc. It ain't all new and factory fresh tight. You might like to search key words like "neutral pressure" "techstream" and "AHS" for lots of good info on understanding and maintaining your system.
Mini-VCI is the cheapo Chinese interface cable with chip that comes with cracked techstream software to hook up your vehicle's obd 2 port. $35 off eBay, runs in an XP or Win7 if you can follow the instructions recently posted up by another member. It's the knock off version of "the computer" Toyota/Lexus dealers use for diagnostics, code reading and resetting (and relieving you of $). Invaluable for neutral pressure checking, changing factory variable settings and observing 100s of vehicle parameters. When people talk about techstream they refer to techstream + interface cable, be it mini vci, tactrix, mongoose or what ever. The mini vci with cracked techstream is the cheapest option out there. Use it once and it's more than paid for itself. You can also buy temp access to legit techstream thru Toyotas maintenance support site, but you still need a vehicle interface cable with compatible drivers.
You haven't actually read your pressures yet, attached is the procedure out of the FSM. Note there is a typo for front pressure; you want to target 6.9Mpa and not 6.5 as is first printed, and for the rear you ideally want to fall around 6.2Mpa within the 5.6 to 6.7 range so trim packers or new coils may be the answer there. Height acc usually comes in around 10.5Mpa, nothing to adjust for this one. Your FR/FL height sensors suggest you may not be on level ground, if you are on perfectly level ground you may need to tweak the sensor adjusters at some time. But one thing at a time, so get your front pressures read and TBs adjusted accordingly.
high
nuteral 
low 
high 
nuteral 
low
