Is This Normal? An AHC Question (1 Viewer)

[Humpzilla]

Hey All,

I've got a 2000 LX470 with the original AHC still going strong (?) at 245k miles. I believe the only thing that has been replaced is the front shocks, due to leaking, by the previous owner (done within the last two years).

Anyway, I will occasionally cycle through the ride height modes, just to work the system. Not sure if I should be doing this or not, but I feel like checking it for functionality every few months isn't a bad thing. That way I can catch any issues before I'm out in the middle of nowhere on a trail.

I've noticed recently that, when I have done this, it can take a really long time for the height to adjust. When I attempted to go into 'Hi' mode yesterday while parked, the light just kept blinking without anything happening (maybe for 20-30 seconds). I put it in drive and then reverse, and eventually it did go into Hi. Same thing when I went from normal to low.

It just seems like it takes a little coaxing and patience to get the AHC to respond these days.

My question is .... is this pretty normal for AHC to do? Or, is it a symptom of impending failure of one or more of the components? Is there something I should be checking or doing?

I've checked the 'gradients' between hi and low, and it seems to be within reasonable spec. Both of the Land Cruiser shops I've taken it to for other work (including TorFab), have been pretty adamant that they don't / won't service the AHC system and that they believe it is better to leave it all alone....which seems odd to me, but I don't know.

Thank in advance for any answers / observations / feedback on this!

Cheers,
Jeff

 

[planomateo]

AHC is constantly adjusting the ride height while you're driving.

Out of curiosity, were you testing this on level ground? It won't budge with the doors open either.

Rather than testing it going into high/low, have you replaced the fluid, confirmed the pressures and adjusted the torsion bars to tune things? Way more important than going into high / low in my opinion.

 

[Humpzilla]

AHC is constantly adjusting the ride height while you're driving.

Out of curiosity, were you testing this on level ground? It won't budge with the doors open either.

Rather than testing it going into high/low, have you replaced the fluid, confirmed the pressures and adjusted the torsion bars to tune things? Way more important than going into high / low in my opinion.

Thanks for the reply! I was on level ground with doors closed. I haven't replaced the fluid yet, but that sounds like the next thing to do. I haven't checked pressures or adjusted the torsion bars either. May have to look into that, but it may be a little above my level of mechanical competency / comfort zone.

 

[planomateo]

@suprarx7nut did a great video on this, AHC Basics for dummies Video re CrossLeveling, Height Sensor adjustment, TB tweaking Previously you'd have to read through the monster AHC thread to understand how it works.

Best of luck.

 

[suprarx7nut]

Hey All,

I've got a 2000 LX470 with the original AHC still going strong (?) at 245k miles. I believe the only thing that has been replaced is the front shocks, due to leaking, by the previous owner (done within the last two years).

Anyway, I will occasionally cycle through the ride height modes, just to work the system. Not sure if I should be doing this or not, but I feel like checking it for functionality every few months isn't a bad thing. That way I can catch any issues before I'm out in the middle of nowhere on a trail.

I've noticed recently that, when I have done this, it can take a really long time for the height to adjust. When I attempted to go into 'Hi' mode yesterday while parked, the light just kept blinking without anything happening (maybe for 20-30 seconds). I put it in drive and then reverse, and eventually it did go into Hi. Same thing when I went from normal to low.

It just seems like it takes a little coaxing and patience to get the AHC to respond these days.

My question is .... is this pretty normal for AHC to do? Or, is it a symptom of impending failure of one or more of the components? Is there something I should be checking or doing?

I've checked the 'gradients' between hi and low, and it seems to be within reasonable spec. Both of the Land Cruiser shops I've taken it to for other work (including TorFab), have been pretty adamant that they don't / won't service the AHC system and that they believe it is better to leave it all alone....which seems odd to me, but I don't know.

Thank in advance for any answers / observations / feedback on this!

Cheers,
Jeff

Thanks for the reply! I was on level ground with doors closed. I haven't replaced the fluid yet, but that sounds like the next thing to do. I haven't checked pressures or adjusted the torsion bars either. May have to look into that, but it may be a little above my level of mechanical competency / comfort zone.

The shop's responses are really common, unfortunately. AHC is a complex system, but the basic maintenance is a piece of cake. Arguably easier than changing your engine oil. When shops are unfamiliar, they generally just refuse to work on it or tell customers they need to convert to a traditional system. Even happens at dealers, unfortuantely.

Anyways, check out my video on testing and adjusting T-bars. I would bet $10 your pressrues are too high and that's forcing the hydraulic system to work a little harder than intended, resulting in long raise times. The fix is completely free (once you have techstream running) and only takes a few mins to turn the t-bars. N to H should take 15 seconds of less, but 10-25 seconds is pretty common.

You need techstream and a mini-VCI cable. There's a thread on here detailing how to do that (Techstream in 5 minutes). Alternatively, there are some standalone scanners that work, but it's hit or miss and you'll spend $100+ for most options I've seen. Techstream and a VCI cable is very powerful and cheap, albeit annoying to get setup the first time.

Don't be scared and good luck! This forum has a wealth of knowledge on the system and how to maintain it.

 

[Humpzilla]

The shop's responses are really common, unfortunately. AHC is a complex system, but the basic maintenance is a piece of cake. Arguably easier than changing your engine oil. When shops are unfamiliar, they generally just refuse to work on it or tell customers they need to convert to a traditional system. Even happens at dealers, unfortuantely.

Anyways, check out my video on testing and adjusting T-bars. I would bet $10 your pressrues are too high and that's forcing the hydraulic system to work a little harder than intended, resulting in long raise times. The fix is completely free (once you have techstream running) and only takes a few mins to turn the t-bars. N to H should take 15 seconds of less, but 10-25 seconds is pretty common.

You need techstream and a mini-VCI cable. There's a thread on here detailing how to do that (Techstream in 5 minutes). Alternatively, there are some standalone scanners that work, but it's hit or miss and you'll spend $100+ for most options I've seen. Techstream and a VCI cable is very powerful and cheap, albeit annoying to get setup the first time.

Don't be scared and good luck! This forum has a wealth of knowledge on the system and how to maintain it.

Wow, THANK YOU for taking the time to type out this response. This is incredibly helpful. Not sure why I thought the process to check pressures and adjust T-bars was more daunting than it seems it actually is. I will dig into this. Sounds like a good little winter project to keep me busy for an afternoon!

 

[Humpzilla]

@suprarx7nut did a great video on this, AHC Basics for dummies Video re CrossLeveling, Height Sensor adjustment, TB tweaking Previously you'd have to read through the monster AHC thread to understand how it works.

Best of luck.

Hey, thanks for the link. I will definitely check this out. I think I've been more intimidated by AHC than I really should have been. Seems like something I can tackle, for sure.

Cheers!

 

[GTV]

It also won’t work if you’ve been holding your foot on the brake for more than 5 seconds or so.

 

[suprarx7nut]

I think I've been more intimidated by AHC than I really should have been.

If there's any phrase to properly sum up AHC, that's it right there.

 

[Humpzilla]

It also won’t work if you’ve been holding your foot on the brake for more than 5 seconds or so.

Ohhhhh, that might have been part of my problem. Good to know!

 

[ramangain]

I've got a 2000 LX470 with the original AHC still going strong (?) at 245k miles. I believe the only thing that has been replaced is the front shocks, due to leaking, by the previous owner (done within the last two years).

I've noticed recently that, when I have done this, it can take a really long time for the height to adjust. When I attempted to go into 'Hi' mode yesterday while parked, the light just kept blinking without anything happening (maybe for 20-30 seconds). I put it in drive and then reverse, and eventually it did go into Hi. Same thing when I went from normal to low.

Was your foot mashed on the brake pedal? Sometimes the AHC won't "start" the re-leveling process on my rig if I have my foot mashed on the brake pedal. Check for a correlation between gear selection, vehicle speed, and brake application.

 

[suprarx7nut]

Ohhhhh, that might have been part of my problem. Good to know!

The times I stated assume you're in park, foot off the brake. If you're on the brake sometimes it'll still raise, but you'll be binding up the suspension a bit. As the car moves up and down the wheels will naturally roll slightly, so you don't want to hold them locked in place with the brakes.

 

[neckbone]

@suprarx7nut did a great video on this, AHC Basics for dummies Video re CrossLeveling, Height Sensor adjustment, TB tweaking Previously you'd have to read through the monster AHC thread to understand how it works.

Best of luck.

I second this video. If you can't check out your AHC after watching this video, you should probably be buying brand new cars with extended warranties. It's literally idiot proof. Changing your fluid takes more technical/mechanical knowledge than leveling and checking/adjusting pressures. I would recommend using a breaker bar to adjust your torsion bars. I didn't try with a ratchet, but the breaker bar made it super easy.

 

[Humpzilla]

I second this video. If you can't check out your AHC after watching this video, you should probably be buying brand new cars with extended warranties. It's literally idiot proof. Changing your fluid takes more technical/mechanical knowledge than leveling and checking/adjusting pressures. I would recommend using a breaker bar to adjust your torsion bars. I didn't try with a ratchet, but the breaker bar made it super easy.

I haven't watched the video yet, but thank you! You have shamed me into getting off my ass and doing this myself. Just kidding .... sort of. Haha.