To add to the comments already offered ....
There are at least two very separate problems in the reported case:
1. The ‘lean’:
The physical 'lean' of 1.5 inches has nothing to do with AHC (unless the system has some incredibly unusual fault such as a jammed Gate Valve inside the Control Valve Assembly).
The physical lean has nothing to do with the Height Control Sensors, whatever their condition.
The physical lean will not and cannot be corrected by a new Sensor.
This physical 'lean' cannot be corrected by Techstream.
The LC100/LX470 AHC/TEMS system is a two-channel (Front and Rear) system. It can raise/lower the Front and Rear separately. The system cannot and does not adjust height settings at individual wheels separately.
The physical ‘lean’ is a mechanical problem. It is fixed only with the torsion bar adjusters per the attached extract from the FSM.
If the vehicle is stationary or steering straight ahead, then the Gate Valves in the Control Valve Assembly are open. This means that the Right Front AHC is connected to the Left Front AHC and so both are at the same pressure. Ditto Right Rear is connected to Left Rear and so both are at the same pressure. [Note: The Front and Rear AHC circuits are not hydraulically connected].
This is why it is impossible to ‘cross level’ the Front of the vehicle with the Height Control Sensors. Attempts to do so may affect the height of the vehicle and also will affect the measured Front AHC pressure – but whatever this pressure may be, it will be the same on both Front Left and Front Right, so the weight carried by the AHC system will be the same on both sides.
A ‘lean’ at the Front relates either to
- the torsion bars carrying unequal loads (most likely and very common, especially if there have been misunderstandings and if uninformed adjustments have been made to the suspension in the past), OR,
- there is some other mechanical problem with mechanical suspension components, OR,
- there is structural damage to the chassis, OR,
- sometimes there are simple side-to-side differences in overall wheel/tyre outside diameter caused by different tyres, different wear or different tyre pressures, OR,
- there maybe combinations of these conditions.
First things first on any AHC review or suspension adjustment:
- forget about Techstream until later in the review,
- first, use a tape-measure and torsion bar adjusters to equalise the Front hub-to-fender heights per first attachment,
- it does not matter what the measurements are this stage, just make them as equal as possible,
- later in the process, after the Front has been ‘cross levelled’ correctly, and when it comes time to set the ‘ride height’ of the vehicle, then the ‘ride heights’ will be set using the Height Control Sensor Adjusters,
- ‘ride height’ is not by set the torsion bar adjusters. This detail is one of the fundamental differences between an AHC suspension and a conventional suspension – ‘ride height’ is not set by torsion bar adjusters on an AHC suspension.
The next step is to get the AHC suspension into its FSM-specified operating ranges. To do this, the Height Control Sensors and their connectors and harnesses have to be electrically healthy.
2. The Sensors:
The reported Diagnostic Trouble Code (DTC) C1711 is coupled with the huge difference in the Front Sensor readings -- assume these are meant as Front Right (FR): -6.3 inches; Front Left (FL): -0.2 inches??? If so, plainly there is a Sensor problem which must be resolved. (What is ‘LR’ in your post? There is only one Rear Sensor which presumably is designated 'RR').
This condition causes the AHC Electronic Control Unit (ECU) to place the suspension in ‘fail safe’ mode. The causes and effects are described in the second attachment – extracted from the FSM.
In ‘fail safe’ mode,
- Active Height Control (AHC) functions are prohibited -- will not raise/lower -- and so it will be impossible to read AHC pressures and these will read as zero on Techstream. It also will be impossible to determine overall ‘globe’ condition by measuring difference in graduations at the AHC Tank at “HI” and “LO” height settings. [It still will be possible to read the Height Control Sensor readings on Techstream – as you have done],
- Toyota Electronic Modulated Suspension (TEMS) functions are prohibited – no adaptive variable damping, so ride will be rough, especially at town speeds.
More details are given in the second attachment extracted from the FSM. These details include a simple method of testing the electrical health of the Height Control Sensors.
Note that the Sensors are VERY simple devices, basically the same kind of potentiometer as invented by Thomas Edison way back in 1875 or thereabouts. There are no clever electronics inside these things. The FSM indicates that these Sensors are meant to operate in a range of 0.3 to 4.7 volts DC.
It is recommended that ALL Height Control Sensors be tested, including any new Sensors purchased --
before installation or when Sensor problems arise.
Sometimes Sensors respond to cleaning. Disassembly is simple. This may be worth a try but be wary of electrical imperfections which may not be visible. These Sensors have a very long life but they are ‘wear parts’. Replacement eventually becomes necessary and is worth considering, especially if 20 years and 185,000 miles in a hostile environment under the vehicle -- heat, cold, water, mud, snow, salt, roadgrit, sticks, stones, whatever -- is consider enough and if reliability is important.
The next step is to follow the procedures laid out in the video and summary sheet provided by
@suprarx7nut at
AHC Info - https://www.yotamd.com/blogs/news/ahc-info
The information assembled by
@LndXrsr also is important reading:
The ABCs of AHC - How to Measure, Flush, and Adjust all in one place - https://forum.ih8mud.com/threads/the-abcs-of-ahc-how-to-measure-flush-and-adjust-all-in-one-place.1211999/
If not seen before, the very readable general description, explanation and diagrams of the AHC/TEMS system on LC100/LX470 is recommended. See link:
https://lc100e.github.io/manual/
Then follow the Index tabs:
New Car Features > CHASSIS > Suspension > Active Height Control Suspension and Skyhook TEMS
