Thank you
@hiikk in Malaysia. From your pictures it can be seen that your vehicle is a Right Hand Drive Toyota Landcruiser Cygnus. It is not clear whether it has a V8 gasoline engine (2UZ-FE) or whether it has a 6-cylinder turbodiesel (1HD-FTE). The engine details do not affect the AHC situation but there may be some effect on how to set up Techstream or other scanner.
The underside of the vehicle appears to be in good condition. Very little rust is visible.
All four ‘globes’ are from Toyota/Lexus. Your previous message indicated that all ‘globes’ were replaced about one year ago. May we assume that the AHC fluid was replaced at the same time?
By the way, it is important to use only genuine Toyota/Lexus AHC Fluid (Part No. 08886-01805 in 2.5 litre drum or Part No. 08886-81221 in 1 litre plastic bottle) in the AHC system. Other fluids can cause major problems and damage to internal parts of the AHC system.
The AHC fluid looks dark in your tank but maybe that is just the effect of the light in the photograph. The colour of new AHC fluid would look pink as shown in my earlier reply. If there is any doubt the age and condition of the AHC Fluid, then it is best to replace it. The fluid deteriorates with age and old fluid can be the cause of uncomfortable ride.
The front Left and front Right Height Control Sensors appear to be intact but the condition of the single rear Height Control Sensor is not visible and is unknown. However, the only way to know the condition of these Sensors is to remove them and inspect and test them electrically as described in the Factory Service Manual (FSM) and on IH8MUD. Malfunctioning Sensors can cause AHC problems. We can come back to Sensor problems later if necessary.
There are several different kinds of fault conditions which can cause the Electronic Control Unit (ECU) to put the AHC system into ‘fail-safe’ mode. This protects the AHC system and the vehicle from damage.
As
@LndXrsr mentioned previously, a common cause of this situation is when the AHC pressures are too high in the front or the rear parts of the AHC system. In such a case, the ECU can prevent the AHC from raising to “HI” because that requires even higher AHC pressures.
Your description explains that there are no heavy loads in the vehicle or on the vehicle, so overloading does not appear to be the cause. By the way, if the vehicle is overloaded, it will refuse to raise to “HI” and may drop to “LO”.
It now is important to use Techstream or other scanner to check the front and rear AHC hydraulic pressures.
These pressures must be in the specification ranges set out in the Factory Service Manual (FSM). These details can be found at
https://lc100e.github.io/manual/ . At the Index in the left hand panel, follow the tabs starting at Repair Manual > SUSPENSION AND AXLE > ACTIVE HEIGHT CONTROL SYSTEM >
ON-VEHICLE INSPECTION. This section sets out the required front and rear AHC pressure ranges.
The front pressures can be adjusted using the torsion bar adjusters underneath the vehicle. The bolts are turned clockwise to increase the load carried by the torsion bars. This has the effect of reducing the front AHC pressures. High rear AHC pressure is more difficult to correct as changes to rear springs or the addition of ‘spacers’ is required.
The recommended first step for your vehicle is to measure the front and rear AHC pressures. If these are too high, they should be corrected. If the pressures are in the correct range, then it is time to look for other causes.
You also may find it helpful to read about how the AHC system works. A general description can be found at
https://lc100e.github.io/manual/ (Follow the index tabs starting at the top:
New Car Features > CHASSIS > Suspension > Active Height Control Suspension).
Please advise if you have been able to check the AHC pressures? If possible, can you please post a screenshot of the readings?
