LX570 AHC “Basics” - Added as sticky thread for AHC Issues (4 Viewers)

[lx200inAR]

I fully raised my height sensors to fit slightly larger 285/60 Nittos. Toyota has never made it easy to run larger tires on the front ... I didn't notice any uneven wear on tires or driving difference. And just a one inch larger diameter tire makes a big difference. Would like to go bigger but I love the AHC function. But now this thread has me wondering if I should replace the fluid as a precaution at 72,000 miles.

I suspect the OP got his answers back in 2021 when he posted. But if you raise or lower with sensors on an AHC truck (or any IFS where you don't make any changes to the control arms) you should get an alignment afterwards, or accept that your alignment is now off. Changing sensor height changes the position of the tire in it's arc of motion, so it's not at the same angle to the road after the changes.

Also, moving sensors makes little difference in the size tire you can fit. As inferred above, changing sensor height only changes the static position of the suspension within it's preset range of motion. The range of motion doesn't change unless you install bumpstops or something to limit compression (which I'm not suggesting).

 

[JKTrevecca]

Greetings and thanks to all who have contributed to this thread! This is my first time dealing with the AHC system on my wife's 08 570. Dash lights came on and message said to check AHC system. I hooked up Tech-Stream and found it had a code for left rear ride height sensor. Crawled under and removed the sensor. Then... I happened to notice the 3-wire harness leading to it was damaged. So... I re-installed the sensor, removed the harness, repaired it, and the dash light and message are gone. BUT.... I must have bent or moved the ride height sensor or bracket b/c everything is "off" now.

I hooked tech-stream back up and the Left Rear ride height sensor reads almost the opposite of the right rear now. For example, the "after adjustment" height in tech-stream for the left-rear is 5.8 inches but the right rear is -5.5 inches.

The AHC system won't work. If I try to raise/lower the truck, the "high" or "lo" flashes but nothing happens. No noises. Etc.

I crawled under with the tech-stream running and adjusted/bent the sensor bracket and the system started working but everything is all wonky and un-level now.

Can someone point me to the easiest and best way, with or without tech-stream, to "adjust" and "calibrate" the ride height sensors. I've thought that perhaps I connected the 3 broken wires backwards perhaps? Anyway, thanks in advance for any suggestions or help you can offer!

 

[poppe]

What size tube is needed for the bleeder valves?

And I see there are front and rear globes by these order numbers. Are their a left and right as well?

 

[rherrco]

What size tube is needed for the bleeder valves?

And I see there are front and rear globes by these order numbers. Are their a left and right as well?

View attachment 3922410

The fronts are a little higher pressure, but no difference in left or right. The difference is faintly stamped on the globe bodies if you mix them up, as I found out only after installing them wrong. Hose I.d. is 4 mm / 3/16 IRC.

 

[poppe]

Damn it. I was doing so well. On the last bleed and I’m getting the AHC error. Is anyone in the Los Angeles or Ventura County Area able to help with Tech Stream?

 

[lx200inAR]

Greetings and thanks to all who have contributed to this thread! This is my first time dealing with the AHC system on my wife's 08 570. Dash lights came on and message said to check AHC system. I hooked up Tech-Stream and found it had a code for left rear ride height sensor. Crawled under and removed the sensor. Then... I happened to notice the 3-wire harness leading to it was damaged. So... I re-installed the sensor, removed the harness, repaired it, and the dash light and message are gone. BUT.... I must have bent or moved the ride height sensor or bracket b/c everything is "off" now.

I hooked tech-stream back up and the Left Rear ride height sensor reads almost the opposite of the right rear now. For example, the "after adjustment" height in tech-stream for the left-rear is 5.8 inches but the right rear is -5.5 inches.

The AHC system won't work. If I try to raise/lower the truck, the "high" or "lo" flashes but nothing happens. No noises. Etc.

I crawled under with the tech-stream running and adjusted/bent the sensor bracket and the system started working but everything is all wonky and un-level now.

Can someone point me to the easiest and best way, with or without tech-stream, to "adjust" and "calibrate" the ride height sensors. I've thought that perhaps I connected the 3 broken wires backwards perhaps? Anyway, thanks in advance for any suggestions or help you can offer!

The sensor bracket has an adjustment range. Did you mark or take a picture of the bracket position. If you have something to get you back to close I’d do that first. If that doesn’t work, you can get vehicle on level ground then get the side that is good set where it shows height to be 0 (while in N). From there turn off the motor but leave vehicle on. Use a floor jack to get the other side at an equal height. Then adjust the misaligned sensor until techstream reads as close to 0 as possible. It’s not high precision, so just looking to get close here. Don’t worry about any of the height adjust fields. Just use the actual height measurements.

 

[poppe]

Just fyi if you have the AHC error and you can’t get it off by turn off and on the vehicle. Pull the fuses from the glove box on the drivers side. There is a 10 and 20 next to each other.

 

[lxluther]

has anyone just used a bleeding kit like a mity vac to suck out the old fluid from the four corners?

 

[lx200inAR]

has anyone just used a bleeding kit like a mity vac to suck out the old fluid from the four corners?

You already have gravity working against the shocks, and the pressure in the globes to force out fluid. Not sure why you need a vacuum. Also, the suspension and the reservoir are not generally connected to each other. Only during a lift is the reservoir connected.

 

[paulunm]

Agree, AHC is nothing like a hydraulic brake system- use the pressure from the pump/globes to do the work for you.

 

[relaxing]

Trying to get to that impossible rear no. 5 height tube union on the pump side... Of course mine is seized and finessing it with a crowfoot wrench isn't working.

Has anyone removed this bump stop? Apparently what Toyota calls 52216-60050 Stopper, Cab Mounting Cushion

Getting it out would gain more access, but I'm not keen on unbolting the body to get into it.

Advice?

 

[relaxing]

Or to really get desperate, would anyone recommend for/against cutting into the wheel well here? (right below that circle)

 

[tbisaacs]

Or to really get desperate, would anyone recommend for/against cutting into the wheel well here? (right below that circle)
View attachment 3959156

Before doing that, might be easier / less destructive to unbolt the rear body mounds and jack the body up a little...

 

[grinchy]

So the body mount that’s under the middle seats? It’s not that hard to get too - maybe an hour to pull the seats and peel the carpet back. I had all the body mounts loose in about three hours, and I’m real slow at mechanicking

 

[relaxing]

Got a buddy to help wrench it out the hard way, 1/8 of a turn at a time.

Failure analysis: pinhole leak at the heat shielding wrap. Kind of amazing it was able to empty 2 liters through that tiny hole in such a short period of time.

 

[04UZJ100]

I removed the heat shield at this location and covered it in marine grease. Seems to be a common failure point/mode.

 

[nwfl4runner]

Trying to get to that impossible rear no. 5 height tube union on the pump side... Of course mine is seized and finessing it with a crowfoot wrench isn't working.

Has anyone removed this bump stop? Apparently what Toyota calls 52216-60050 Stopper, Cab Mounting Cushion

Getting it out would gain more access, but I'm not keen on unbolting the body to get into it.

Advice?

View attachment 3959098

View attachment 3959099

That mount is a bolt In the center of the bump, inside the body is just a weld nut. I was able to wiggle a small socket into it, otherwise you’ll have to loosen the rear body mounts and get some space by jacking up the body

The one you access from the inside is just a bolt, no bump