Ah crap, it doesn't say in the first post, and I failed to read the additional posts by @IndroCruise , that the crossleveling needs to be done with the AHC off. Wonder if that's why weird height changes happened in the middle of my cross-leveling experiment.
To clarify,
1. Crosslevel fronts with AHC OFF
2. Turn AHC back ON
3. If front height not in spec, adjust using the sensor adjustment? I don't get this part - am I trying to get the "height control sensor" readings to 0 in Techstream, OR am I trying to adjust the front heights by re-measuring hub-to-fender heights? And how would I know which way to move the sensor heights to adjust the hub-to-fender height?
Never mind, clearly I need to keep reading!
You are probably across it all by now -- but the following notes were prepared and may as well be posted now for more happy reading .....
Keep calm and carry on!! A few things have been mixed up in the descriptions in your Post #362 and your Post #363 but no damage is done. You are just having a version of the same ‘learning experiences’ that we all had in the beginning ….
Start the engine, set the height to “N” -- and let the vehicle height stop where it will.
Now, turn
“OFF” the engine
and ignition (which then turns
“OFF” the AHC system)
and leave them all
“OFF” until mentioned later -- because it is safer this way, and, because the FSM says so.
Forget about Techstream and lock it away until Step 13 below,
Forget about the ‘reservoir test’ -- do not even think about this until Step 23 below -- otherwise it is not comparable with the FSM numbers and tells you nothing useful.
You have done very well so far -- suggest continue with patience and determination. Here are some notes which may help:
The underlying sequence in these notes for adjusting the AHC system is no different to other Posts you may have read -- the sequence is always the same when making AHC adjustments and measurements -- these notes just add more detail which may clarify some points:
1. ‘Cross-level’ the Front of the vehicle
on a level surface using
only the torsion bar adjusters and a tape-measure (
never the Height Control Sensor adjusters and Techstream). The first attachment (extract from FSM) gives some guidance – might need to wind up one side and wind down the other. Per FSM,
IT DOES NOT MATTER what the tape-measurements are at this stage -- you just want them to be equal within +/- 10 millimetres per FSM, and preferably even closer to equal,
2. You do
not want the Active Height Control (AHC) system to be ‘active’ at this ‘ cross levelling’ stage -- otherwise the AHC system may attempt to make ‘corrections’ and in effect try to contradict your ‘adjustments’ while you are making them! If this happens, confusion, frustration and re-work are absolutely guaranteed!!
3. One consequence is that if the Height Control Sensors are so maladjusted (or faulty) that they send wrong or widely different signals to the ECU, then the ECU may enforce the ‘fail safe function’ in which AHC operation and TEMS operation are both prohibited – see second and third attachment. This is easily fixed -- but it requires that all previous adjustments be unpicked,
4. The purpose of Front ‘cross levelling’ step is two-fold – (i) to eliminate any unacceptable side-to-side ‘lean’ -- within +/- 10 millimetres (+/- 0.4 inches) side-to-side on the vehicle when on a level surface, not carrying any poorly distributed loads or fittings, wheels straight ahead,
and, (ii) to equalise the load on the LHS torsion bar and the RHS torsion bar,
5. On an AHC-equipped vehicle, ‘cross-levelling’, and, the torsion bar adjusters
have nothing to do with setting the ‘ride height’ of the vehicle,
6. On an AHC-equipped vehicle, the Height Control Sensors do not and cannot be used to adjust the relative side-to-side heights of the vehicle and so the
Height Control Sensors adjusters cannot be used in ‘cross levelling’. This is because in the AHC system, LH Front and RH Front are hydraulically connected – via the Front Gate Valve in the Control Valve Assembly which is “normally open” at all times except when the vehicle is cornering at speed. Ditto the AHC system at LH Rear and RH Rear and via the Rear Gate Valve. So any effort on just one side at the Front with the the Height Control Sensors adjusters will simply raise or lower the vehicle when it is started -- and it will result in wrongly adjusted Sensors, ongoing confusion and possibly the 'fail safe function' being implemented by the Suspension Electronic Control Unit (ECU),
7. For now, assume that the vehicle is not in ‘fail safe function’ -- this can be confirmed if the AHC system is able to raise and lower the vehicle,
8. With ‘cross levelling’ sorted, it is time to set the ‘ride height’ of the vehicle at “N” height -- for a stock vehicle (not lifted),
irrespective of tyre and wheel size, targeting
Front hub-to-fender 19.75 inches (or 500 millimetres) and
Rear Front hub-to-fender 20.50 inches (or 520 millimetres), measured with a tape-measure. Note that these are not Toyota nor Lexus FSM measurements but are easy-to-measure, widely accepted approximations which have stood the test of time.
9. Different ‘ride heights’ can be targetted, for example if the aim is a so-called ‘sensor lift’ -- but suggest leave that until later. First, adjust the vehicle in standard condition at “N” height,
10. The point is that these ‘ride heights’, when set, are the heights to which the AHC system will self-level the vehicle every time at “N” height setting,
provided that the 16 to 24 years old Height Control Sensors actually are in healthy condition (???), and, the AHC system is functioning correctly,
11. Again, assume that the vehicle is not in ‘fail safe function’ -- this can be confirmed if the AHC system is able to raise and lower the vehicle,
12. Again, also assume that the Height Control Sensors are in healthy condition -- noting that the absence of a Height Control Sensor Diagnostic Trouble Code (DTC)
does not provide assurance that these Sensors are healthy -- removal and testing with a multimeter per FSM is necessary. (Note: If original, the Height Control Sensors on a 2006 LX470 are now 17 years old -- they are long-life items but live in a hostile environment, they have moved with each and every up-and-down vertical movement of the suspension as the vehicle travels -- they are subject to wear, weakening of internal contacts, water ingress, internal corrosion, harness problems – they do not last forever. At this age, suggest always remain suspicious of the condition of the Height Control Sensors --
especially when large differences are seen between the Height Sensor readings on Techstream when the vehicle is known to have been ‘cross-levelled’ correctly with equalised side-to-side heights per Step 1, and is sitting on a level surface),
13. Now break out Techstream -- initially to use with Ignition “ON”
but with engine “OFF” (because initially some static readings are necessary without the AHC system itself attempting any auto adjustments),
14. ALWAYS, WHEN MAKING ADJUSMENTS ON THE AHC SYSTEM, ENSURE BEFORE STARTING THAT VEHICLE STANDS ARE PLACED UNDER THE CHASSIS RAILS FOR PERSONAL SAFETY, IN A WAY THAT ENSURES THAT IT IS IMPOSSIBLE FOR THE VEHICLE BODY TO DESCEND ONTO A HUMAN BODY UNDER THE VEHICLE IF A MISTAKE IS MADE,
15. There are various ways to set the chosen ‘ride height’. They all involve manual adjustments and tape-measurements and are not done by pressing some button in Techstream. All methods have the same principles in common: (i) to physically adjust (raise or lower) the Front and Rear of the vehicle body relative to the wheel hub until the desired hub-to-fender
tape-measured distances are achieved, then (ii) hold that position, then (iii) with the vehicle at the set ‘ride heights’ with Ignition “ON”
but with engine “OFF”, the Height Control Sensors readings are adjusted as close as possible to zero (within +/- 0.2 inches or within +/- 5 millimetres) per Techstream
,
16. Using the
“Height Control Operation Test -- Active Test” with engine “ON” to physically raise or lower the vehicle is one method of adjusting the preferred ‘ride heights’. This described in in Section 5 at Page 6 of the fourth attachment (sourced long ago from the highly experienced
@PADDO -- and it works for me). The procedure must be followed
exactly. It uses Diagnostic Link Connector 1 (DLC1) in the engine bay above the RHS Front wheel arch – an unbent paper clip or similar suffices in place of Special Service Tool SST 09843-18020 -- or you can buy this jumper lead from a local Dealer or elsewhere. Note: Techstream cannot be connected and operated at DLC3 under the dash during this procedure involving DLC1,
17. With the vehicle in position at the preferred ‘ride heights’ to match “N” height setting, then with Techstream attached and with Ignition “ON”
but with engine “OFF”, move the sliders on the Height Control Sensor adjusters until the Height Control Sensor readings are as close as possible to zero (within +/- 0.2 inches or within +/- 5 millimetres) per Techstream readings,
18. It may be necessary to use the double-ended heim bolts on the Front to gain the necessary movement, just be aware that these are very fiddly to adjust,
19. Moving the Height Control Sensor adjusters is awkward because this involves reaching around the tyre -- it easier on a platform hoist, wheels must be supporting the vehicle, not hanging free,
20. An alternative method is to remove each Front wheel one-by-one and then use a jack under the Lower Control Arm to produce the required actual tape-measured Front hub-to-fender distance, then move the Height Control Sensor adjuster as close as possible to zero while observing the Sensor reading on Techstream with Ignition “ON”
but with engine “OFF”,
21. The Rear Height Control Sensor adjuster (slider only, no heim bolt) can be reached from under the vehicle --
AGAIN, TAKE CARE AS MENTIONED IN STEP 14,
22. Then when the ‘ride heights’ are set as desired, and not before, check Front and Rear AHC pressures using Techstream -- adjust as necessary with torsion bar adjusters in Front (and/or with torsion bar re-indexing if the Front is very heavy), and, at Rear with spacers to pre-load coil springs or preferably upgrade the coil springs. Before recording AHC pressures, always wait ~30 seconds after the “N” to “LO” to “N” height movement is completed (green AHC light stops flashing in instrument cluster) to be sure that the AHC Pump has completed the raise
and also has re-charged the Height Control Accumulator. (Note that use of the torsion bars will not cause changes to ‘ride height’ because ‘ride height’ is controlled by the Height Control Sensor signals to the Suspension ECU),
23. When the ‘ride heights’ are set as desired,
and, Front and Rear AHC Pressures are within the FSM-specified range, then and not before, check overall condition of ‘globes’ by observing how much AHC Fluid is displaced by the ‘globes’ to the AHC Tank -- looking for the difference in fluid levels after moving from “HI” height to “LO” height per FSM -- should be around 14 graduations with new ‘globes’
under FSM-specified conditions. (Note: Just to be clear, correct AHC pressures within FSM ranges tells
nothing about 'globe' condition),
24. Note that all AHC-related adjustments are made at “N” height setting -- no adjustments are possible at “LO” height nor at “HI” height. However, observations at “LO” and “HI” can be a useful check – but beware of inconsistencies if there are differences in torsion bar settings, rear spring condition, wear and tear in mechanical suspension parts – bushings, control arms, ball joints, bearings etc, etc – or uneven tyre pressures or different tyre wear side-to-side. It is always good to measure times to raise “LO” to “N” and “N” to “HI” -- slow times
may be an early indicator of a partial blockage building up in the internal strainers inside the AHC Pump, or,
may be an indicator of faults in the Height Control Sensor
harness and circuits, causing inconsistent signals to the ECU and resulting in slow response times.