AHC/Suspension HELP!!

[OS+LC100]

I need some assistance on a weird AHC & Suspension issue on my 2001 50th Anniv. Ed., Petrol, 'matic version, 31,000 km. It started 3 weeks ago when we went into a soft and muddy reclaimed area in Low 4-wheel drive control setting which automatically made the suspension harder (as noted on the manual, in any suspension mode: AHC indicator was N height and suspension in Normal). After going back to the main road, shifted back to H gear but noticed that the LC was still riding hard but didn't mind it.

I finally noticed the next day going to work, the ride was so bumpy. Not only was it HARD, but the front height (only) has lifted as well while the dash height indicator was in Low and a blinking OFF to match! I tried asking the local Toyo. service but they could not help since I had an imported unit (local vers. has no AHC options).

I tried a number of different combinations of shifting between L & H gear, driving reverse and forward hoping a stuck sensor or something would go back to normal. At one point, it did, but the following day, it was back to hard suspension & High front/Low rear height. I noted the AHC reservoir marker has dipped by 4 lines from normal. The only way to make the ride a little softer and tolerable for the family was to take out the fuse of the AHC from the fusebox, although the unusual stance of the LC held up.

At one time, the front height went lower than the back (checked the AHC reservoir and it was about 2 lines higher than normal)... so replaced back the fuse which caused it back to its unusual setting. I'm concerned that if I continue to do this taking/replacing the fuse and driving the LC in this condition, I may further damage other parts.

Hope somebody out there can help me resolve this problem.

Thanks in advance!!
Oscar

ps... I have ordered 3 cans of AHC in preparation for any possible fixes

 

[hoser]

Seems like the two most common AHC problems are 1) failed height control sensors--there are two in the front, one in the rear or 2) failed accumulators.

I think I would start by checking the rear Height Control Sensor. The sensors don't have a good weather seal and are prone to internal rusting. New ones retail for US$333. Make sure you mark the position before removing it.

 

[Jim_Chow]

I bet the height control sensors leaked, shorted out, or are out of adjustment. When in 4wd low, if you set the AHC to "H," it'll go into an extra high mode, like 3"+ higher than "N" mode. I wonder if that (in the future) might help prevent dragging the height sensors through the mud?

 

[hkeller]

I'm with Jim. Yes, it is possible you could have blown out your rear accumulators, but it is much more likely that water and mud shorted out one of the height sensors.

Let's narrow it down a bit. Did you have a great deal of weight in the back of the rig? Is the back now sitting lower than normal, or is the front just higher? If the back is lower, and if you were carrying a bunch of weight in the rear (and the back is now a lot lower than normal, like on the bumpstops), it is possible you blew out the rear accumulators. I really doubt it.

Check the voltage across the sensors first. If you can't do this, take them apart and clean off any corrission and reseal and reinstall them. Then, unhook the battery for a few minutes, to clear the computers, and try again.

Let us know what happens.

 

[hoser]

Jim, to keep the water out, I heard you could open the sensors and reseal it better than factory with silicone sealant. I have not looked it at that closely yet. Heck, while you are there, might as well extend the differential breather hoses too.

 

[HDJ100L]

OSCAR,
is your LANDCRUISER converted? i used to hear that many LX470 and LANDCRUISER that comes from Japan has the problem of the AHC and sometimes the automatic tranny too. this is due to the conversion of the right hand drive to left hand. as you are aware some company who do the conversion does not have the complete parts for the landcruiser. i also had a friend of mine who has trouble with AHC and he has to spend more than $2000 to fix it. and there is no guarantee to cure the problem. i would suggest if cannot fix the problen just change your shocks to the regular one.

Kingston
Banilad...

 

[hkeller]

It will take more than just changing shocks to switch to a normal suspension. You'll also need to switch in regular springs and torsion bars. There will also be a lot of components to remover (hydraulic, computer, wiring). This will have some negative impact on resale value. Before you dump the whole system, try a few of the simple checks discussed above. I'll bet it will fix it.

H.

 

[Drinkin40s]

Has anyone done the suspension switch? I love the AHC, but wondered if it is possible.

 

[OS+LC100]

Thanks guys for the advise, will try to check on it this weekend. I'm thinking of bleeding the system as well while I'm at it, but can't do that until the AHC fluid arrives from the US.

Jim .. you're right, that was what I was planning to do if things got messy but didn't see the need at that time to shift H-AHC. Too late now!!

hkeller ... I had about 8 kg. worth of tools at the back, no third seat - so I think its not a weight related issue. The unusual position of the LC now: front is in ultra high height and the rear is within or slightly lower than normal height. Will clean, check out the voltages/sensors as per hoser's recommendation.

Kingston ... no, my LC is not a surplus/conversion - its an original European version. Where in Banilad are you at??

 

[OS+LC100]

Seems like the two most common AHC problems are 1) failed height control sensors--there are two in the front, one in the rear or 2) failed accumulators.

I think I would start by checking the rear Height Control Sensor. The sensors don't have a good weather seal and are prone to internal rusting. New ones retail for US$333. Make sure you mark the position before removing it.

Hi Hoser --- thanks for your suggestions. Do you have the part numbers for the height sensors?? ... just in case I need to order new ones (hope not!) Thanks, Oscar

 

[hoser]

Height Control Sensor
Right 89405-60011
Left 89406-60011
Rear Suspension 89407-60010

These are the Lexus part numbers. The equivalent Toyota part might be cheaper (and easier for you to get). Sorry, I don't have the Toyota Part Number.

 

[uHu]

Oscar,
FYI, I have 3 times had the same problem, but at the rear. 1st time it was a branch that had bent the linkage to the sensor. 2nd & 3rd times it was caused by corrosion in the rear sensor. Fix was first time to get a new height sensor on the factory warranty. Second time I just cleaned it up and filled it with oil. The corrosion was both times at one or two of the 3 little springs connecting the lid with the carbon slider to the back where the plug is. Pretty easy to clean with some contact cleaner and a small screwdriver, and maybe some fine sandpaper. Looks like the front sensors are a bit more difficult to get to though. You should also check the electrical connection to the sensors, the cable and plugs at (above/behind) the wheels.
What's the year and mileage of your cruiser?
Good luck.

 

[haulin79]

If you disable the AHC and continue to use the stock springs and shocks, will it sit at the minus 2 inches height?

 

[uHu]

If you take all pressure out of the system, it will sit on the bump stops.
If you switch it off (e.g. by entering diagnostics mode) it will just stay where you left it.

 

[OS+LC100]

uHu .. its a 2001 50th Anniv. Ed. Petrol w/ 31,000+ km. Hmm, surprisingly the Toyo. engrs. didn't do a good job designing the AHC system on our LC100s. I just found a local mechanic who had work at 5 other 100s with the same problem. Will check up all the parts mentioned in this thread and hopefully they are all repairable.

How does one enter the diagnostic mode?? Does anybody know how or if its possible to read the problems of the system through the touch/screen panel?

Thanks!!

 

[OS+LC100]

Height Control Sensor
Right 89405-60011
Left 89406-60011
Rear Suspension 89407-60010

These are the Lexus part numbers. The equivalent Toyota part might be cheaper (and easier for you to get). Sorry, I don't have the Toyota Part Number.

Thanks hoser!!

 

[Jim_Chow]

uHu .. its a 2001 50th Anniv. Ed. Petrol w/ 31,000+ km. Hmm, surprisingly the Toyo. engrs. didn't do a good job designing the AHC system on our LC100s. I just found a local mechanic who had work at 5 other 100s with the same problem. Will check up all the parts mentioned in this thread and hopefully they are all repairable.

How does one enter the diagnostic mode?? Does anybody know how or if its possible to read the problems of the system through the touch/screen panel?

Thanks!!

The USA AHC vehicles seem to have few problems. We've had AHC here on all LX470's since '98, and the LX outsells the LC here. Problems seem to be mainly from someone adding the wrong fluid to the AHC resevoir and that fluid eventually destroying the membrane in the damping globes.

 

[Tinkerer]

The USA AHC vehicles seem to have few problems. We've had AHC here on all LX470's since '98, and the LX outsells the LC here. Problems seem to be mainly from someone adding the wrong fluid to the AHC resevoir and that fluid eventually destroying the membrane in the damping globes.

I wonder if the reason for fewer problems with LX470 AHC in USA is due to overall less severe offroad service for that group, compared to LC overall and/or LX in other regions? (USA LX tend to be on-road vehicles for the most part?)

 

[Jim_Chow]

I wonder if the reason for fewer problems with LX470 AHC in USA is due to overall less severe offroad service for that group, compared to LC overall and/or LX in other regions? (USA LX tend to be on-road vehicles for the most part?)

Could be. There are supposedly a lot of LX's in the Middle East, but again, those are dry conditions. Maybe those height sensors have an aversion to water/mud. We don't get those conditions out here in AZ..it's more like the Mideast...dust/sand storms, dry & hot.

 

[tabraha]

Yeah most LX's here are pampered but my AHC components have been covered in mud for 2 or 3 years now and keep on tickin'. Maybe they are sealed by it by now.