Definitive list of AHC maintenance items (6 Viewers)

[uHu]

No, you are not supposed to manually adjust the sensors to zero. That's what the ahc system is supposed to do for you. The main function is that it pumps up the pressure until the sensors read zero. That your system stops before it reaches zero is strange indeed.
Is this a typical reading for every time you move from Lo to Norm height? Do you let it go all the way down to Lo, let it settle, and then let it go all the way to Norm, wait 30 sec and then check the reading? Do you ever see zero on the height reading?

Flaky signal from height sensors can give harsh ride or varying heights. The sensors give the ECU input about the road condition in addition to the actual height, which is used particularly for wash-board control, e.g.

 

[JMC3]

No, you are not supposed to manually adjust the sensors to zero. That's what the ahc system is supposed to do for you. The main function is that it pumps up the pressure until the sensors read zero. That your system stops before it reaches zero is strange indeed.
Is this a typical reading for every time you move from Lo to Norm height? Do you let it go all the way down to Lo, let it settle, and then let it go all the way to Norm, wait 30 sec and then check the reading? Do you ever see zero on the height reading?

Flaky signal from height sensors can give harsh ride or varying heights. The sensors give the ECU input about the road condition in addition to the actual height, which is used particularly for wash-board control, e.g.

@uHu the readings are consistent. I haven't waited and exceptional amount of time at low. Typically 5 or 10 secs I guess.....

 

[JMC3]

@uHu the readings are consistent. I haven't waited and exceptional amount of time at low. Typically 5 or 10 secs I guess.....

I suppose I can dig into the sensor

No, you are not supposed to manually adjust the sensors to zero. That's what the ahc system is supposed to do for you. The main function is that it pumps up the pressure until the sensors read zero. That your system stops before it reaches zero is strange indeed.
Is this a typical reading for every time you move from Lo to Norm height? Do you let it go all the way down to Lo, let it settle, and then let it go all the way to Norm, wait 30 sec and then check the reading? Do you ever see zero on the height reading?

Flaky signal from height sensors can give harsh ride or varying heights. The sensors give the ECU input about the road condition in addition to the actual height, which is used particularly for wash-board control, e.g.

No, you are not supposed to manually adjust the sensors to zero. That's what the ahc system is supposed to do for you. The main function is that it pumps up the pressure until the sensors read zero. That your system stops before it reaches zero is strange indeed.
Is this a typical reading for every time you move from Lo to Norm height? Do you let it go all the way down to Lo, let it settle, and then let it go all the way to Norm, wait 30 sec and then check the reading? Do you ever see zero on the height reading?

Flaky signal from height sensors can give harsh ride or varying heights. The sensors give the ECU input about the road condition in addition to the actual height, which is used particularly for wash-board control, e.g.

I could dig in and test/clean all of the sensors or simply replace them, but it strikes me as strange that all 3 are out of whack. I suppose its possible....

 

[uHu]

What are the height readings when coming down from Hi to N?
The thing is that it's the height sensors reading (close to) zero that stops the suspension moving from either Hi or Lo to N, so, when it stops at N and the sensors are not close to zero, there must be something else stopping it.

 

[PabloCruise]

I didn’t. Am I supposed to manually adjust them to zero? I did a multimeter check on the front sensors and everything seems ok. I don’t remember reading from @PADDO, @uHu, @IndroCruise, @PabloCruise or the rest of you gurus that I should manually adjust the height sensors to zero once everything is in spec. Is that the prescribed action? That makes things easy if that is what I am supposed to do.

No, you are not supposed to manually adjust the sensors to zero. That's what the ahc system is supposed to do for you. The main function is that it pumps up the pressure until the sensors read zero. That your system stops before it reaches zero is strange indeed.
Is this a typical reading for every time you move from Lo to Norm height? Do you let it go all the way down to Lo, let it settle, and then let it go all the way to Norm, wait 30 sec and then check the reading? Do you ever see zero on the height reading?

Flaky signal from height sensors can give harsh ride or varying heights. The sensors give the ECU input about the road condition in addition to the actual height, which is used particularly for wash-board control, e.g.

Not trying to be difficult, but when I read the @PADDO posts, I read where after everything else is dialed in and set up, you adjust the sensors:

Definitive list of AHC maintenance items

I sprayed them with PB blaster about 30 minutes before I began working on them. Pretty sure this is the first time these have been adjusted given the amount that was needed to get the system back in line. When I went to start turning them, it wouldn't budge at all at first. So I jacked up the...

forum.ih8mud.com

Perhaps I am not understanding the content of his message?

 

[uHu]

...after everything else is dialed in and set up, you adjust the sensors:...

Yes, you are right. You adjust the sensors to get the car to the right height, or to get the two front sensors to agree on where zero is when one reads plus and the other reads minus. In this case, all the sensors show 1/4 inch too little when the AHC stops lifting, and this is not an adjustment issue. Now, 4 to 7 mm is not much, and the system might be working perfectly OK otherwise.
Otoh, It could in fact be a good exercise to adjust all sensors to zero, and then test Lo to Norm again, to see if it still stops at 1/4 " under zero (with the car at a 1/4" lower height as well). Doing that would also include in a close examination of the sensor linkages, which can be too loose, or even binding.

 

[JMC3]

Yes, you are right. You adjust the sensors to get the car to the right height, or to get the two front sensors to agree on where zero is when one reads plus and the other reads minus. In this case, all the sensors show 1/4 inch too little when the AHC stops lifting, and this is not an adjustment issue. Now, 4 to 7 mm is not much, and the system might be working perfectly OK otherwise.
Otoh, It could in fact be a good exercise to adjust all sensors to zero, and then test Lo to Norm again, to see if it still stops at 1/4 " under zero (with the car at a 1/4" lower height as well). Doing that would also include in a close examination of the sensor linkages, which can be too loose, or even binding.

@uHu, I think you are correct. Something is not quite right with the sensor readings. I would expect FL and FR to average to 0. But they're all low. Weird. Truck is riding nicely. I will review heights sporadically over the next few days and see if the N resting heights are moving around. If they are, then I will fiddle with(or swap) What does it mean when the rear shows low? could a tweaked rear sensor stop the height adjustment and cause the spurious front readings? Not sure what to make of this.....

 

[IndroCruise]

@uHu, I think you are correct. Something is not quite right with the sensor readings. I would expect FL and FR to average to 0. But they're all low. Weird. Truck is riding nicely. I will review heights sporadically over the next few days and see if the N resting heights are moving around. If they are, then I will fiddle with(or swap) What does it mean when the rear shows low? could a tweaked rear sensor stop the height adjustment and cause the spurious front readings? Not sure what to make of this.....

Hi @JMC3,

I mentioned in my post #837 in this thread that I would provide a write-up of my own experiences of my AHC system “refusing to go zero”, with Height Control Sensor readings persistently showing negative 4 millimetres to negative 8 millimetres in the FSM-prescribed N >> LO >> N test , despite efforts at adjustments. This write-up and some responses have been posted separately at

AHC – so slow, erratic, what to do next? Help requested please

In my case, the ‘cause’ of the ‘effects’ I have observed remain unresolved and I have invited input.

My choices are to stop overthinking the issue, or, to persist with the investigation! After all, in any technical system, every ‘effect’ has a ‘cause’.

Given the extensive maintenance and replacement history on my vehicle as listed at the above link, at the moment I am wavering between

• simple mechanical causes such as hydraulic obstructions, ‘tight’ bushes in the suspension and/or frictional interference between rear springs and my optional airbags or anything else impeding suspension movement, and,
• more complicated causes such as an errant Sensors (even though new), or AHC Pump problems (even though new), problems with the Height Control Accumulator and its solenoid valve (all new), or an errant original AHC Electronic Control Unit (ECU), and,
• moving on and finding something else to think about!

My approach has been to start with the more simple and more likely causes and methodically fix or eliminate them before moving on to other more complicated and less likely possibilities. The “Problem Symptoms Table” (FSM Repair Manual DIAGNOSTICS section at Page DI-221 -- https://lc100e.github.io/manual/) gives a few ideas as a starter. It does not give all the possibilities but the suggested sequence seems worthwhile.

I would be interested in any progress you make ......

 

[silver02accord]

I had my ahc pressures front 6.7 and rear 6.2 a few months back. Since then I have added weight including sliders, full aluminum skids, land shark full drawers, iceco 65 qt fridge, goal zero 3k battery and loaded the drawers with light weight camping/back pack gear.

Before leaving on a desert trip this weekend I measured pressures at 6.10 front and 9.4 rear after first Re cross leveling with full load. Obviously the rear is high and I plan on adding king springs.

We drove with a full load and 2 additional passengers (combined weight 265 lb pound) to the desert and probably as you would suspect truck would not go to H. Also I didn't notice when but while driving the truck said it was in L but the height appeared to be at the the N height. When I started up the next day the truck said N even though I never changed the height manually.Damping modes were working we used comfort and full sport on washboard to confirm. I tried to go in H in the desert with all passengers out of the vehicle and it would not go. When I returned home after a few hr drive it went into H (I was only passenger just like before). Then my wife got in car weight 130 and it would not go to H once more.

We are leaving for moab this week for white rim trail, Fins and some other mellower trails. I don't think I can get springs installed before we leave.

Is there significant harm in running this heavy load for a few days /weeks while I wait on replacement springs? I may need H out there and not certain if it would raise up when needed. Would you think distbuting more of the load over the center of the vehicle in 2nd row(water container, etc) would take some weight off the rear springs and would be more beneficial given the overload? My oem springs are original pretty certain. If I am going to add a bumper down the road should I consider 100 non ahc springs instead? One more thought was to increase front pressures to help lower rear - I was under impression when you crank tb clockwise to reduce front pressure that it can increase your rear pressure.

The fluid was flushed, well maintained with flushes over its life and has worked well thus far - I intend on keeping the ahc.

 

[PabloCruise]

I had my ahc pressures front 6.7 and rear 6.2 a few months back. Since then I have added weight including sliders, full aluminum skids, land shark full drawers, iceco 65 qt fridge, goal zero 3k battery and loaded the drawers with light weight camping/back pack gear.

Before leaving on a desert trip this weekend I measured pressures at 6.10 front and 9.4 rear after first Re cross leveling with full load. Obviously the rear is high and I plan on adding king springs.

We drove with a full load and 2 additional passengers (combined weight 265 lb pound) to the desert and probably as you would suspect truck would not go to H. Also I didn't notice when but while driving the truck said it was in L but the height appeared to be at the the N height. When I started up the next day the truck said N even though I never changed the height manually.Damping modes were working we used comfort and full sport on washboard to confirm. I tried to go in H in the desert with all passengers out of the vehicle and it would not go. When I returned home after a few hr drive it went into H (I was only passenger just like before). Then my wife got in car weight 130 and it would not go to H once more.

We are leaving for moab this week for white rim trail, Fins and some other mellower trails. I don't think I can get springs installed before we leave.

Is there significant harm in running this heavy load for a few days /weeks while I wait on replacement springs? I may need H out there and not certain if it would raise up when needed. Would you think distbuting more of the load over the center of the vehicle in 2nd row(water container, etc) would take some weight off the rear springs and would be more beneficial given the overload? My oem springs are original pretty certain. If I am going to add a bumper down the road should I consider 100 non ahc springs instead? One more thought was to increase front pressures to help lower rear - I was under impression when you crank tb clockwise to reduce front pressure that it can increase your rear pressure.

The fluid was flushed, well maintained with flushes over its life and has worked well thus far - I intend on keeping the ahc.

Whatever you do, don’t tell your wife the truck won’t go into H because she got in...

 

[ramangain]

I had my ahc pressures front 6.7 and rear 6.2 a few months back. Since then I have added weight including sliders, full aluminum skids, land shark full drawers, iceco 65 qt fridge, goal zero 3k battery and loaded the drawers with light weight camping/back pack gear.

Before leaving on a desert trip this weekend I measured pressures at 6.10 front and 9.4 rear after first Re cross leveling with full load. Obviously the rear is high and I plan on adding king springs.

We drove with a full load and 2 additional passengers (combined weight 265 lb pound) to the desert and probably as you would suspect truck would not go to H. Also I didn't notice when but while driving the truck said it was in L but the height appeared to be at the the N height. When I started up the next day the truck said N even though I never changed the height manually.Damping modes were working we used comfort and full sport on washboard to confirm. I tried to go in H in the desert with all passengers out of the vehicle and it would not go. When I returned home after a few hr drive it went into H (I was only passenger just like before). Then my wife got in car weight 130 and it would not go to H once more.

We are leaving for moab this week for white rim trail, Fins and some other mellower trails. I don't think I can get springs installed before we leave.

Is there significant harm in running this heavy load for a few days /weeks while I wait on replacement springs? I may need H out there and not certain if it would raise up when needed. Would you think distbuting more of the load over the center of the vehicle in 2nd row(water container, etc) would take some weight off the rear springs and would be more beneficial given the overload? My oem springs are original pretty certain. If I am going to add a bumper down the road should I consider 100 non ahc springs instead? One more thought was to increase front pressures to help lower rear - I was under impression when you crank tb clockwise to reduce front pressure that it can increase your rear pressure.

The fluid was flushed, well maintained with flushes over its life and has worked well thus far - I intend on keeping the ahc.

Drive to your Toyota dealership and just get LC springs. Pay the dealership premium to get them and you install them. If they aren't the best solution after your trip, you can sell them on here very easily and get the proper springs of your choice.

Don't go offlroading without being able to access H. Why? In case you get stuck and the rig wants to activate Xtra high mode, you want that ability.

 

[silver02accord]

Drive to your Toyota dealership and just get LC springs. Pay the dealership premium to get them and you install them. If they aren't the best solution after your trip, you can sell them on here very easily and get the proper springs of your choice.

Don't go offlroading without being able to access H. Why? In case you get stuck and the rig wants to activate Xtra high mode, you want that ability.

The trip went well in moab. The truck did go to h some time but other times not. The hardest trail we ran was fins and tower Arch(which was great btw nobody there).

Just installed king ktrs-79. The pressure went from 9.4 to 7.3-7.4 in the rear. This is fully loaded with tools, recovery gear, full tank gas, 65l fridge and 3k yeti battery and another 100 lbs in misc gear with me in the car. I am getting 12 gradations so I think globes are fine.

Heading to death valley and I'll see how it rides this weekend. It seems like spacers may be in order(0.5 improvement)? I am not always going to drive fully loaded so I may try to split the difference. I haven't checked pressures unloaded yet but will do after I unpack in a few days.

If I understand correctly the next step up from the kings is the lx450 springs? The ride quality is imrpvoed over the original oem springs, not as floaty.

 

[ramangain]

^ run it and enjoy. As I said before, I'm impressed with what you've done since you've joined.

 

[PabloCruise]

The trip went well in moab. The truck did go to h some time but other times not. The hardest trail we ran was fins and tower Arch(which was great btw nobody there).

Just installed king ktrs-79. The pressure went from 9.4 to 7.3-7.4 in the rear. This is fully loaded with tools, recovery gear, full tank gas, 65l fridge and 3k yeti battery and another 100 lbs in misc gear with me in the car. I am getting 12 gradations so I think globes are fine.

Heading to death valley and I'll see how it rides this weekend. It seems like spacers may be in order(0.5 improvement)? I am not always going to drive fully loaded so I may try to split the difference. I haven't checked pressures unloaded yet but will do after I unpack in a few days.

If I understand correctly the next step up from the kings is the lx450 springs? The ride quality is imrpvoed over the original oem springs, not as floaty.

View attachment 2506730

Did you have the dealer install LC 100 series springs?

 

[silver02accord]

Did you have the dealer install LC 100 series springs?

I did not. Ran the oem old tires springs in moab. Kings on for dv

 

[suprarx7nut]

The trip went well in moab. The truck did go to h some time but other times not. The hardest trail we ran was fins and tower Arch(which was great btw nobody there).

Just installed king ktrs-79. The pressure went from 9.4 to 7.3-7.4 in the rear. This is fully loaded with tools, recovery gear, full tank gas, 65l fridge and 3k yeti battery and another 100 lbs in misc gear with me in the car. I am getting 12 gradations so I think globes are fine.

Heading to death valley and I'll see how it rides this weekend. It seems like spacers may be in order(0.5 improvement)? I am not always going to drive fully loaded so I may try to split the difference. I haven't checked pressures unloaded yet but will do after I unpack in a few days.

If I understand correctly the next step up from the kings is the lx450 springs? The ride quality is imrpvoed over the original oem springs, not as floaty.

View attachment 2506730

I did not. Ran the oem old tires springs in moab. Kings on for dv

Awesome feedback and info. Great stuff. This sort of thing is really helpful for others trying to figure out how to ride that line of convenience and reliability with AHC. Glad your trip was unhindered by AHC.

You seem to be in a similar boat to me. My pressures are similar with the King springs. I have spacers waiting to install. I think that'll get you (and I) pretty close. I think the LX450 springs are next in line, but am not 100% on that. OEM LC springs would be after that, maybe, but I suspect that would be too much spring. For the 100 LC springs to be appropriate you have to be nearly 30-40% over stock weight if my napkin math is right. That's like.... 1100 extra lbs on the rear axle alone. I think you're still a ways shy of that.

Anxious to hear where you end up. Keep us updated!

 

[overl4nd]

Hello fellow mudders. Insurance totalled our GX 470, and in a couple of days she will be gone. We had very good memories with her. Got at 150,000 miles, and now gone at 220000

Expense was OME lift kit and then a ARB bumper after a deer hit.
Very reliable and solid.

Now for an upgrade, we did think about a 2016 Tundra due to space to carry stuff like telescopes. But then lack of dust proofing (even with a cap) and insane 38K+ prices put us off.

Along cames a LX 2011, around 150,000 miles done. Seller is asking 28K.

I am wondering apart from pulling the carfax/Autocheck (I just need VIN I guess), what else should I check.

Things I should do...

1. 14 clicks from L to H. Or above 10?
2. Check fluid using a straw. Should be pink
3. Shocks and springs, what to check?
4. Rust of course


I have techstream. What should I check on techstreaM?

 

[PabloCruise]

Hello fellow mudders. Insurance totalled our GX 470, and in a couple of days she will be gone. We had very good memories with her. Got at 150,000 miles, and now gone at 220000

Expense was OME lift kit and then a ARB bumper after a deer hit.
Very reliable and solid.

Now for an upgrade, we did think about a 2016 Tundra due to space to carry stuff like telescopes. But then lack of dust proofing (even with a cap) and insane 38K+ prices put us off.

Along cames a LX 2011, around 150,000 miles done. Seller is asking 28K.

I am wondering apart from pulling the carfax/Autocheck (I just need VIN I guess), what else should I check.

Things I should do...

1. 14 clicks from L to H. Or above 10?
2. Check fluid using a straw. Should be pink
3. Shocks and springs, what to check?
4. Rust of course


I have techstream. What should I check on techstreaM?

Hello!

You found a 2011 LX?
That should be a LX-570, aka 200 series Land Cruiser.
For the 100 series/LX-470, I like to check the AHC suspension pressures using TechStream. I am not sure how this process works for the 200 series. There is a 200 series section here on MUD!
Good luck...

 

[rally roo]

Crap, did I just draw air into the AHC plumbing? My reservoir has been a little low, and I wanted to pull off the side steps so I could flush the system more easily. Pulled into the garage and clicked to HIGH to make work underneath easier, and the system couldn’t go to up all the way, then settled back to N and flashed the OFF light at me. I think there wasn’t enough fluid in the reservoir to go all the way up; will I have to chase bubbles during the flush?

Also, while I was under there, I noticed my FDS lower shock body was wet and caked; presumably the reason for the low fluid level. Are these serviceable at all, or does this mean replacement? The RDS upper shock body has a hole in it too, exposing the piston - is this a big issue? If I’m replacing one, should I do them all?

 

[suprarx7nut]

Crap, did I just draw air into the AHC plumbing? My reservoir has been a little low, and I wanted to pull off the side steps so I could flush the system more easily. Pulled into the garage and clicked to HIGH to make work underneath easier, and the system couldn’t go to up all the way, then settled back to N and flashed the OFF light at me. I think there wasn’t enough fluid in the reservoir to go all the way up; will I have to chase bubbles during the flush?

Also, while I was under there, I noticed my FDS lower shock body was wet and caked; presumably the reason for the low fluid level. Are these serviceable at all, or does this mean replacement? The RDS upper shock body has a hole in it too, exposing the piston - is this a big issue? If I’m replacing one, should I do them all?

I suggest you follow the YotaMD Cheat Sheet. If you did pull air into the system, it's a good time to flush with new fluid which is never a bad thing.

Shocks can weep with AHC if your neutral pressures are too high. Think of it as the shock crying because you're asking it to work too hard.

The shock can have seal failures and legitimately need replacement, but start by ensuring neutral pressures are correct.

If you do need replacement, they're $200-220 each. Not bad.