LX570 AHC “Basics” - Added as sticky thread for AHC Issues (9 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.