Have a 2005 Land Cruiser and some months ago the AHC off light switched on and off continuously, the control itself not seeming to function; depressing of the button caused the hi or low indicator light to flash before returning to normal, effectively there was no control. Took the vehicle out yesterday and noticed the off light was not flashing and the mode indicator was showing lo setting; drove off and the vehicle took off like a camel crossing the sands. Checked and topped up the reservoir, listened for the pump when trying different modes, dit deaf so cannot say it the pump is running, however judging by the height of the vehicle I imagine it is! Again took the vehicle on a run and again was in the up and down operation and the suspension height was some 20cm from top of tyre to bottom of wheel arch, hot rod style. Parked the car up for a while, 3 hours, an on starting again with the body still elevated was a bit surprised when it lowered to normal height and the off light was again flashing. Drove for about 20 minutes with the handling as normal as ever, no bounce and no concern other than the flashing indicator. Stopped the vehicle and parked up for about 10 minutes, switched on and started up only to notice the indicator had dropper down to lo and the light was out, drove off and again the bounce was back. Any observations and advice that may bring a modicum of comfort here in rural France!
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Land Cruiser 100 AHC problem
- Thread starter Eliphanta
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I've no info on these but have you tried a search on here Eli? I'm pretty sure there's some threads about the AHC. Might give you a quick answer. Sounds like a leak to me but that's just a guess.
Good luck with it.
Good luck with it.
SafariTecPeter
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Faulty AHC is AFAIK a bag of rattle snakes.
This can be caused by "everything" from a faulty pump, pressure loss in the accumulators, height sensors, shot shocks etc etc
IMO U may want to get it properly diagnosed before venturing WAY kneedeep in this unless You are overly familiar with it.
This can be caused by "everything" from a faulty pump, pressure loss in the accumulators, height sensors, shot shocks etc etc
IMO U may want to get it properly diagnosed before venturing WAY kneedeep in this unless You are overly familiar with it.
I know nothing of technology other than it confuses me, thank you for your advice; I have to imagine the fault, or one thereof to be electrical, for the vehicle has been riding high today and when moving some 100 metres the suspension settled back to what I imagine to be normal, albeit the back is higher than the front, normal? Will take it to the specialist for a diognosis, should this be Toyota Main Dealer?
SafariTecPeter
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This may be a AHC ECU issue.. or at least a height sensor out of wack...
If no independet Toyo LC specialist is nearbu You, them head for a main dealer for a diagnosis!
With this in hand You can decide what to do.
Servecing these "older" AHC plants can become very dear financially.
Personally I have ripped it out & replaced it with a full OME Lift kit for a number of reasons.
If no independet Toyo LC specialist is nearbu You, them head for a main dealer for a diagnosis!
With this in hand You can decide what to do.
Servecing these "older" AHC plants can become very dear financially.
Personally I have ripped it out & replaced it with a full OME Lift kit for a number of reasons.
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SafariTecPeter
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The "worst" was getting out the (rear) shocks
I definately was not willing to drill through the floor so I cut opp the top of the shock with a recipro saw!
Took a long time but I did not damage "anything else".
Did the same on the front too as I was "in the mood"...
Fitting the shocks & the new springs was straight forward.
You will (!!) need new torsion bars on the front. Don`t even bother to try with the original AHC bars...
I learned this the hard way taking a known (in my area) OME dealer`s word that I would be OK with stock bars...
I also added a bracing that OME offers to the front end. Good piece of kit while You are at it.
I have rescently also fitted a full set of Superpro bushes in order to "zero out" the suspention wear.
Has truely transformed the ride to become very firm & direct. The way I like it
I have & I am in the process of adding some permanent weight to it whichs is why I fitted a heavy duty setup.
While I was fitting the OME kit, I spoke to the local Toyo Shop. They shared some horror stories with reference to the AHC system & costs involved.
As nice as it may be, it requires quite some effort to keep up to date when it ages
I definately was not willing to drill through the floor so I cut opp the top of the shock with a recipro saw!
Took a long time but I did not damage "anything else".
Did the same on the front too as I was "in the mood"...
Fitting the shocks & the new springs was straight forward.
You will (!!) need new torsion bars on the front. Don`t even bother to try with the original AHC bars...
I learned this the hard way taking a known (in my area) OME dealer`s word that I would be OK with stock bars...
I also added a bracing that OME offers to the front end. Good piece of kit while You are at it.
I have rescently also fitted a full set of Superpro bushes in order to "zero out" the suspention wear.
Has truely transformed the ride to become very firm & direct. The way I like it
I have & I am in the process of adding some permanent weight to it whichs is why I fitted a heavy duty setup.
While I was fitting the OME kit, I spoke to the local Toyo Shop. They shared some horror stories with reference to the AHC system & costs involved.
As nice as it may be, it requires quite some effort to keep up to date when it ages
Hearing your symptoms, I agree it could be electrical. This is generic troubleshooting here. It might just be worth having a crawl around under your truck and checking that the sensors are all mechanically connected and that there is no damage to wiring and there is no water in any plugs. Look for wear to the wiring, that sort of thing. Have a really good look. Did this start after a significant event? Big bump, obstacle, water, that sort of thing. Anything that could give a clue.
I would check that the arms on all the height sensors are still connected, there are one on each front suspension that is visible looking just above the front tyre.
There is also one on the rear axle the can really only be seen when under the car, my rear arm broke free from the sensor and caused similar problems.
How many miles has your car done?
There is also one on the rear axle the can really only be seen when under the car, my rear arm broke free from the sensor and caused similar problems.
How many miles has your car done?
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The two most likely problems are faulty sensor (because of water ingress/corrosion) and faulty/loose link/arm or otherwise something that makes the sensor not "see" the movement of the suspension. The third most likely is a broken wire. Check the rear sensor first, very easy to get to.
It would help with more info: Miles, rust, salted roads (ever), any load in the car (or empty), any changes done or parts changed on the suspension system (ever). It would also be good to know the Neutral Pressure of the AHC system (easy to check if you have the computer gadget).
Many toyota dealers have no idea about the ahc system, so ask around before you give it to somone throwing parts at it, on your cost, without beeing able to see where (and why) they are throwing parts. The fault codes (DTC) for the ahc are not to be trusted, so reading codes and changing parts accordingly becomes very expensive.
The ahc is a simple system, but with many parts.
It would help with more info: Miles, rust, salted roads (ever), any load in the car (or empty), any changes done or parts changed on the suspension system (ever). It would also be good to know the Neutral Pressure of the AHC system (easy to check if you have the computer gadget).
Many toyota dealers have no idea about the ahc system, so ask around before you give it to somone throwing parts at it, on your cost, without beeing able to see where (and why) they are throwing parts. The fault codes (DTC) for the ahc are not to be trusted, so reading codes and changing parts accordingly becomes very expensive.
The ahc is a simple system, but with many parts.
Vehicle 2005 has 160000 on the clock, generally driven on normal road surface the odd unmade country lane, (gently) and across the occasional field. Spent most of history in UK and must imagine has been victim to the ravages of snow, ice and salt. Seldom more than two passengers and generally just me, weight in the back maybe 100kg maximum but have put the seats into storage thereby saving about 50g. The height selection is not a facility I use, or indeed have ever used, only again became aware of it earlier in the year when the off light started blinking, did not appear to affect the use of the vehicle, I therefore ignored it. My problem has come to the fore during recent days and the handling of the vehicle becoming a bit erratic and jacking itself to new heights and rocking in a similar way to a small boat on choppy water. I parked up when arriving home yesterday and the vehicle was duly fully extended, later in the evening I moved to the parking area and the suspension returned to normal level; have to say until the last few days I had not been aware of the vehicle height previously moving up or down! This morning after having given some thought to the situation I have removed the 50 amp fuse and imagine effectively isolated the system, albeit the indicator lights remain on, now in lo from N, but flashing off as previously. If as is suggested the possibilities of the Toyota man knowing, or in fact being able to identify the problem, is it considered more prudent to just change the system for a more conventional suspension; I see no prestige in investing money into an aging technology that may continue to throw up faults. I do not off road as a rule, I do not do high mileage, I do tow, sometimes at maximum permissible weight, not though long distance. Vehicle is serviced regularly but not cherished.
Any further suggestions?
Any further suggestions?
Yes, take a look underneath. It's not going to cost you anything to do. You may find something adrift. At least three of us have pointed you in this direction to look for wire damage, detached arms or corrosion to the plugs. With respect, if you want to rip it all out and spend a shed load replacing a system that is a smidge off working ok then that's your choice. If you want to get it going or prove something that's wrong before taking it to Mr T who may know little about it other than how to throw parts at it at your expense, have a look at the sensors and wiring underneath. You don't have to be mechanically minded to do this, and you start taking control of the problem.
BobMurphy
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A Toyota Dealer should be able to perform a Diagnostic Check on the system (and everything else, while they're at it). This should save a lot of checking, fiddling about with things and guessing at what's wrong.
They will charge, of course.
Bob.
They will charge, of course.
Bob.
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The rear sensor (ther is only one at the rear) is located inside the front of the left, rear wheel. The sensor is fitted to a crossmember in front of the rear wheels, and the sensor link-arm with ball joints is attached to the rear axle's upper link-arm (or whatever it's called). Look for loose sensor link, at both ends. The sensor-end is fastened with a small nut onto a small shaft with two flat sides. The bottom end has a small bolt which goes through a little flat piece attached to the rear axle's link arm. That flat piece has a slot in which the sensor link arm can be adjusted up and down.
At the front there's one sensor at each wheel. You can see it just inside the top of the tyre (at least with the suspension in the high position). It's the same sensor as at the rear, but the link-arm is shorter and straight. The front sensors have a plug located on top of the wheel arch under the bonnet. There's one plug for the abs sensor and one for the ahc sensor next to each other.
The suspension system will not continue to work well over time with the fuse pulled.
I do like the ahc system, but I see that it will become expensive to maintain if you cannot DIY. Replacing it with conventional suspension is straight forward, and includes 4 springs and 4 shock absorbers. Removal of other ahc components is optional, but most people remove the 4 actuators with spheres, and the pump as a minimum. At the age of your system, the rear coil springs are probably worn out in any case, giving the ahc system a much to high pressure.
At the front there's one sensor at each wheel. You can see it just inside the top of the tyre (at least with the suspension in the high position). It's the same sensor as at the rear, but the link-arm is shorter and straight. The front sensors have a plug located on top of the wheel arch under the bonnet. There's one plug for the abs sensor and one for the ahc sensor next to each other.
The suspension system will not continue to work well over time with the fuse pulled.
I do like the ahc system, but I see that it will become expensive to maintain if you cannot DIY. Replacing it with conventional suspension is straight forward, and includes 4 springs and 4 shock absorbers. Removal of other ahc components is optional, but most people remove the 4 actuators with spheres, and the pump as a minimum. At the age of your system, the rear coil springs are probably worn out in any case, giving the ahc system a much to high pressure.
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Thank you for the information; unfortunately, am too old and too stiff in the joints to do much at all, one of the reasons I have a Land Cruiser, can climb in and roll out without much folding! Will have the connections investigated and hopefully a poor connection will be evident and when rectified all will again be wonderful for a period of time.
I accept the system cannot be left long term without attention, do we have a time scale in which to change the format; if indeed the proposed investigations are negative and the AHC is to be consigned to the eBay listing! Is there a consensus as to the best replacement to use?
I accept the system cannot be left long term without attention, do we have a time scale in which to change the format; if indeed the proposed investigations are negative and the AHC is to be consigned to the eBay listing! Is there a consensus as to the best replacement to use?
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Re checking sensors: One of the most common problems is internal, either corrosion or worn out carbon traces. It's easy to open up the sensors to check, once you have them in hand. The rear sensor seems to be the first to go.
Re replacement: There is absolutely no consensus. Most people active on LC-forums seem to go for a lift, with taller, stiffer springs. I would go for original springs and any quality shocks. The rear springs do sag over just a few years, expect to change every 100 k, or 5-6 years. The front springs, torsion bars, are adjustable, and keep "for ever". If someone says that you do not have to change the front springs if converting to conventional suspension, then disregard it. They are very different in load carrying capabilities; because with the ahc, the steel springs carry only about half the load.
Re replacement: There is absolutely no consensus. Most people active on LC-forums seem to go for a lift, with taller, stiffer springs. I would go for original springs and any quality shocks. The rear springs do sag over just a few years, expect to change every 100 k, or 5-6 years. The front springs, torsion bars, are adjustable, and keep "for ever". If someone says that you do not have to change the front springs if converting to conventional suspension, then disregard it. They are very different in load carrying capabilities; because with the ahc, the steel springs carry only about half the load.
