Is it plausible that I first have DTC C1711 and C1776 and after fixing those I get C1762? Or do you thing there is still something going on with the sensors?
Probably you already know this, but just to be sure, all AHC testing and measurements on ELMscan or Techstream must be done with all doors and rear hatch closed – AHC system is designed not work if the ECU detects that any of these are open (or with a problem in the door switch circuits). The engine hood can be left open. AHC pressure readings need to be done after moving heights “N” to “LO” to “N”, waiting for the green dashboard light to stop blinking then wait for a further 30 to 60 seconds with engine running before taking readings. This ensures that the raise is complete AND that the AHC Pump has had time to re-charge the Height Control Accumulator and the Pump has stopped. Personally, I have to ‘re-learn’ these lessons most times I do these tests -- such is my impatience!!
As explained in Post #12, C1711 and C1776 are consistent with the then problematic Right Front Height Control Sensor
Circuit (not just the Sensor itself).
Also as explained in Post #4, absence of DTC does NOT provide assurance that a Height Control Sensor is OK and working correctly. The Sensor can be faulty with wrong outputs for the vehicle height but there will be no DTC if this wrong signal remains within the range accepted by the ECU.
Both the Right Front and Left Front Height Control Sensor have now been replaced with new OEM Toyota/Aisin Sensors complete with new harness segment which joins the main AHC harness at a connector above the respective Front Left and Front Right wheel arches.
Unless there is harness damage around those connectors, it seems reasonable to assume these two new Front Sensors
and circuits are in good shape. Suggest assume OK for now. To be sure, you would need a check that the connectors right back at the Electronic Control Unit (AHC) are tight and use a multimeter to check that the voltages in the circuit are correct at the ECU -- see FSM-DIAGNOSTICS section at Page DI-218 – “Terminals of ECU”.
The jury is still out on the Rear Height Control Sensor. The condition of this Sensor is not known. Given that the Rear Sensor is the same age as the Front Sensors, it is worth testing this Sensor per FSM, for confidence that it is working correctly and reliably.
Reported observations are:
FR -63mm
FL -84mm
RR -46mm
In my @HDJ80fan opinion this is correct.
Car is in low.
FL Sensor arm needs little adjustment. That will gain the 20mm.
Rear has King Springs and Spacer. Cant go lower.
Front AHC Pressure: 1.7 MPa
Rear AHC Pressure: 3.3 MPa
Height Control Accumulator Pressure: 0.0 Mpa
The Height Control Sensor readings in ELMscan suggest that either (1) the vehicle may be on the front bump stops, or, (2) all three Sensors are out of adjustment – meaning, not reading “close to zero” at “N” height (probably because it has not been possible get the vehicle to raise to “N”?)
By the way, it is always very helpful to diagnosis when quoting Height Sensor readings also to record and quote the tape-measured hub-to-fender distances on all four wheels at the same time.
Some differences between the Height Control Sensor readings are large: FL to FR is 21 mm (almost three-quarters of an inch), FR to RR is 17 mm, FL to RR is 38 mm.
The FSM is unclear how much difference is enough to put the AHC system into ‘fail safe function’ – but I would be suspicious about the FL to FR difference. Conflicting height sensor signals mean that the ECU cannot resolve the correct vehicle height to match the height selection switch on the console – and instead adopts the ‘fail safe function’.
The Front to Rear differences in height sensor readings are very large. It possible that there is a Rear sensor problem. However, the AHC system on LC100/LX470 is two-channel (Front and Rear) system in which Front and Rear are largely independent, so a Rear sensor problem would not be my first assumption, unless the Rear Sensor reading obviously is inconsistent with the Rear tape-measured hub-to-fender distances.
I don’t think the KING KTRS-79 springs have much to do with it. I have those same springs (but not spacers) and I still get close to the actual physical FSM-specified height changes “LO” to “N” to “HI” within about 5 mm (tape-measured hub-to-fender). You must be carrying an enormous Rear load if both KING KTRS-79 springs AND spacers are required? This combination will result in very low AHC pressures and poor damping performance (more 'springy' ride) when the vehicle is empty or does not have much permanent Rear weight for example Rear bar, drawers etc.
As shown in your ELMscan readout, the required Front and Rear AHC pressures and the Height Accumulator are not building up -- which is why the vehicle is not raising.
Suggest read up on what C1762 means and the specified conditions which give rise to this DTC:
Landcruiser 100 Series Factory Workshop Manual
lc100e.github.io
then use tabs on LHS of opening page
Repair Manual > DIAGNOSTICS > ACTIVE HEIGHT CONTROL & SKYHOOK TEMS > C1762
In response to your last question, it can happen that the ECU displays a DTC for the first problem that it discovers, then when that is fixed, the ECU reveals the next problem it finds in the sequence. Suggest that this method of revelation not be allowed to become a distraction -- just "go with the flow".
Are any other pump-related DTC's showing -- particularly DTC1718, DTC1741, DTC1751?
(In any case, suggest read up on these to get a better understanding of the system -- see same DIAGNOSTIC section of the FSM as referenced previously -- and in particular, note in each case the slightly different 'fail safe functions' which become important symptoms to observe, with or without DTC's).
It is mentioned that the AHC Pump can be heard working "but nothing happens other than noise".
So more information is necessary to start to figure out what that means and why movement is not happening.
Can you please advise for how long the AHC Pump is working before it stops?
Has there been any work on the AHC system (including any bleeding of AHC Fluid) which might have allowed air to enter the system?
When was the AHC Fluid last changed?
What are the hub-to-fender heights at each of the four wheel positions?
How old are the 'globes' on the vehicle?
