AHC Suspension Issues
05-04-16, 11:42 AM
#17
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1999 lx470 ahc
my lx470 ahc will lower when I use the switch and re level to n after i drive over the mph limit. It will not raise to h or back from L to n when I try do do it with the switch. any thoughts?
05-12-16, 07:48 AM
#18
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Hello jksoukup, I just had to deal with my AHC (automatick height control system) of my 2005 LX470, and let me tell you its not an easy thing to diagnose. I think thats why when we go to a dealership, they recomend replacing all the parts, becuase the 20 year old mechanic who worked on our car doesnt understand how things work, he is just going by what the error code techstream is displaying). having said that, it looks like your suspension ECU is acting up, it cant be a sensor since your vehicle goes to normal mode when it goes over 19mph. My recomendation would be to not tinker with the AHC system. as long as the vehicle is driving in N mode you should be fine. Keep in mind that the vehiche is almost 17 years old. And even if you replace the suspension ECU, there is no guarantee that the problem will be fixed, it could be the sensor(s) as well. I had to replace a few parts on my Truck, one by one before my suspension issue was resolved. I know we want things to work 100%, however somethings are best left alone. Good luck, I am sure you love driving this truck around.
11-21-18, 05:21 PM
#19
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2004 LX470 rear suspension bounces sometimes when start driving
Hi, I seem to have a similar issue on my 2004 LX470. When I start driving, sometimes the rear suspensions seems to bounce for a minute or so, and then it settles down. Did anyone experience and reolve such an issue? Any help on the diagnosis would be appreciated.
Hello guys,
Once in while my rear suspension tanks and goes down and the ride becomes bouncy. The fluid levels are fine and when I press AHC botton to bring the vehicle all the way up to H, the fluid level decreases, and when it press the button to bring it to low L, the fluid level in the reservoir increases, which tells me that my AHC pump is fine. However for the life of me I cant figure out why the truck behaves this way. The irony is that AHC self corrects itself and the vehicle comes to its normal State after a while, either while i am driving or when I park the truck. If this is the indication of the rear sensor going bad wont I see some kind of light blinking? I think this is a unique issue and i have not been able to find any answer on any forum. ? Also if you can let me now of any OBDIi scanner that can help read the code that would be helpful. I tried a 50 dollar scanner but it didnt read any codes. Chances are I need a specialized scanner. thank you,
12-03-18, 11:00 AM
#20
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In my case I didnt want to take it to the dealership as it would have cost me a lot of money, however I started replacing parts 1 by 1 and finally when I replaced the the AHC sensor (height control sensor) the suspension started working. Good luck. here is a link to buy from EBAY :
https://www.ebay.com/itm/1998-2007-L...X7j:rk:18:pf:0
12-03-18, 11:57 AM
#21
Pole Position
Before I started throwing parts / $$$ at it...
Start with replacing the sensors, if that doesnt help then replace the AHC motherboard (AKA AHC computer). this is located on the right wall of the accelerator. where your knee rests while you are driving. You can pick it up from the junk yard for a 100-200 bucks depending on where you buy it from.
In my case I didnt want to take it to the dealership as it would have cost me a lot of money, however I started replacing parts 1 by 1 and finally when I replaced the the AHC sensor (height control sensor) the suspension started working.
In my case I didnt want to take it to the dealership as it would have cost me a lot of money, however I started replacing parts 1 by 1 and finally when I replaced the the AHC sensor (height control sensor) the suspension started working.
How many miles / years has it been since the AHC fluid was flushed and replaced?
Pls report back with what you find.
hth
12-22-18, 11:50 PM
#22
Driver
I believe whether car rides better with or without bags is debatable. If you like stiffer ride sure, if comfy maybe not so....another alternative of retaining factory configuration with bags when doing a lift is upgrading bags to bigger ones. There's company out there that makes them, cost is around $700 though. Think I am going this route when time comes 
12-24-18, 11:16 PM
#23
Pole Position
I believe whether car rides better with or without bags is debatable. If you like stiffer ride sure, if comfy maybe not so....another alternative of retaining factory configuration with bags when doing a lift is upgrading bags to bigger ones. There's company out there that makes them, cost is around $700 though. Think I am going this route when time comes
To my knowledge, the only "bags" on the truck are interior air bags.
Toyota's AHC system does not use bags from the factory...it's all hydraulic.
Air bags from AirLift or similar can be used inside the rear springs to keep the truck level with a heavy load...nothing to do with the AHC system other than lowering pressure and keeping the system running longer, at least in theory.
Citreon globes have been tried on Toyota AHC systems with some success. A link to the guy making whatever you call bags would be appreciated. I'd recommend an hour or so on mud reading about how the AHC system works.
05-24-20, 08:08 AM
#24
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Please help!!!!!!
I've read all of the'fixes' butI'm not sure if any apply to my issue. The rear of my 2002 lx 470 has fallen down. I am able to control the height of the front end of the truck but the back end just remains in the lowest position. When I drive it it hits every single bump with major force and I'm jumping around like popcorn in a hot skillet. I don't want to do further damage to my old baby I want to fix the correct thing as well. Please advise
I've read all of the'fixes' butI'm not sure if any apply to my issue. The rear of my 2002 lx 470 has fallen down. I am able to control the height of the front end of the truck but the back end just remains in the lowest position. When I drive it it hits every single bump with major force and I'm jumping around like popcorn in a hot skillet. I don't want to do further damage to my old baby I want to fix the correct thing as well. Please advise
05-25-20, 07:43 AM
#25
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Please help!!!!!!
I've read all of the'fixes' butI'm not sure if any apply to my issue. The rear of my 2002 lx 470 has fallen down. I am able to control the height of the front end of the truck but the back end just remains in the lowest position. When I drive it it hits every single bump with major force and I'm jumping around like popcorn in a hot skillet. I don't want to do further damage to my old baby I want to fix the correct thing as well. Please advise
I've read all of the'fixes' butI'm not sure if any apply to my issue. The rear of my 2002 lx 470 has fallen down. I am able to control the height of the front end of the truck but the back end just remains in the lowest position. When I drive it it hits every single bump with major force and I'm jumping around like popcorn in a hot skillet. I don't want to do further damage to my old baby I want to fix the correct thing as well. Please advise
I will share my experience as a owner of 2005 lx470. I faced the same issue where I could control the front but the rear was down. I tool it to a mechanic and after changing several parts including back sensor, computer and adjusters...etc. I took it to another mechanic who fixed it permanently. He said the issue was electrical and was related to Old wiring. Since the truck is old, this is something you can not avoid. Take it to a knowledgable mechanic and have him check the wiring related to AHC. Mechanics should be able to test the circuit one by one and figure out the problem.
if you have to start with changing the parts then start with the back AHC sensor. Front had two sensors, one for front left and o e for front right, however there is only one sensor for both rear tires. One way a mechanic can test if it's a sensor issue, is by taking a front sensor and put it in the rear. The fitting is different but the sensor is the same, the mechanic should know how to take the casing from the good sensor and put it into the other. If the test passes, then order a new sensor. Problem solved. Dont go on changing the parts randomly. First check the sensor, and then the electrical. 9 out of 10 times this will fix your issue. Good luck.
05-25-20, 08:45 AM
#26
Pole Position
I will share my experience as a owner of 2005 lx470. I faced the same issue where I could control the front but the rear was down. I tool it to a mechanic and after changing several parts including back sensor, computer and adjusters...etc. I took it to another mechanic who fixed it permanently. He said the issue was electrical and was related to Old wiring. Since the truck is old, this is something you can not avoid. Take it to a knowledgable mechanic and have him check the wiring related to AHC. Mechanics should be able to test the circuit one by one and figure out the problem.
if you have to start with changing the parts then start with the back AHC sensor. Front had two sensors, one for front left and o e for front right, however there is only one sensor for both rear tires. One way a mechanic can test if it's a sensor issue, is by taking a front sensor and put it in the rear. The fitting is different but the sensor is the same, the mechanic should know how to take the casing from the good sensor and put it into the other. If the test passes, then order a new sensor. Problem solved. Dont go on changing the parts randomly. First check the sensor, and then the electrical. 9 out of 10 times this will fix your issue. Good luck.
if you have to start with changing the parts then start with the back AHC sensor. Front had two sensors, one for front left and o e for front right, however there is only one sensor for both rear tires. One way a mechanic can test if it's a sensor issue, is by taking a front sensor and put it in the rear. The fitting is different but the sensor is the same, the mechanic should know how to take the casing from the good sensor and put it into the other. If the test passes, then order a new sensor. Problem solved. Dont go on changing the parts randomly. First check the sensor, and then the electrical. 9 out of 10 times this will fix your issue. Good luck.
I'd also take a look at the 100 series tech forum on ih8mud.com. User name PADDO there has forgotten more about AHC than most dealership mechanics know. He's also a member here.
05-28-20, 06:15 AM
#27
I will share my experience as a owner of 2005 lx470. I faced the same issue where I could control the front but the rear was down. I tool it to a mechanic and after changing several parts including back sensor, computer and adjusters...etc. I took it to another mechanic who fixed it permanently. He said the issue was electrical and was related to Old wiring. Since the truck is old, this is something you can not avoid. Take it to a knowledgable mechanic and have him check the wiring related to AHC. Mechanics should be able to test the circuit one by one and figure out the problem.
if you have to start with changing the parts then start with the back AHC sensor. Front had two sensors, one for front left and o e for front right, however there is only one sensor for both rear tires. One way a mechanic can test if it's a sensor issue, is by taking a front sensor and put it in the rear. The fitting is different but the sensor is the same, the mechanic should know how to take the casing from the good sensor and put it into the other. If the test passes, then order a new sensor. Problem solved. Dont go on changing the parts randomly. First check the sensor, and then the electrical. 9 out of 10 times this will fix your issue. Good luck.
if you have to start with changing the parts then start with the back AHC sensor. Front had two sensors, one for front left and o e for front right, however there is only one sensor for both rear tires. One way a mechanic can test if it's a sensor issue, is by taking a front sensor and put it in the rear. The fitting is different but the sensor is the same, the mechanic should know how to take the casing from the good sensor and put it into the other. If the test passes, then order a new sensor. Problem solved. Dont go on changing the parts randomly. First check the sensor, and then the electrical. 9 out of 10 times this will fix your issue. Good luck.
IMO, I would not start throwing parts at it until a dealer or good independent shop (my choice) connects the truck to Toyota's Tech Stream or TIS (Toyota Information System)...that allows checking the system while it's in use.
I'd also take a look at the 100 series tech forum on ih8mud.com. User name PADDO there has forgotten more about AHC than most dealership mechanics know. He's also a member here.
I'd also take a look at the 100 series tech forum on ih8mud.com. User name PADDO there has forgotten more about AHC than most dealership mechanics know. He's also a member here.
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