03 LX470 AHC issue, shop diagnosis? (1 Viewer)

Joined
Jul 16, 2020
Messages
48
Location
maine
Evening Fellas, I suppose I could write a novel but I’ll try for the quick and dirty. We had our clean 03 Fla LX470 into the most local Lexus Indi in Portland Maine today for a harsh ride issue in the front end. I was thinking the torsion bars needed adjustment or possibly a globe issue. The service writer called this afternoon and told us that we didnt find anything “wrong” with the suspension, it functions, and goes to all positions BUT we do need a set of ride height adjusters and that is what is causing our front end harsh ride issues. The quote was $1700. I said how much are the adjusters, $600/side he said then labor for installation. I did a quick google for the parts, appears their attainable for a more lucrative price elsewhere.
Tell me what you know about height adjusters, diagnosing bad ones, and installing new ones + torsion bar adjustments if you dont mind. I cant get my techstream to work but I do have an Icarsoft and a set of 4 wheel scales if applicable. Thanks.
 
Joined
Dec 6, 2016
Messages
672
Location
Brisbane, Australia
Evening Fellas, I suppose I could write a novel but I’ll try for the quick and dirty. We had our clean 03 Fla LX470 into the most local Lexus Indi in Portland Maine today for a harsh ride issue in the front end. I was thinking the torsion bars needed adjustment or possibly a globe issue. The service writer called this afternoon and told us that we didnt find anything “wrong” with the suspension, it functions, and goes to all positions BUT we do need a set of ride height adjusters and that is what is causing our front end harsh ride issues. The quote was $1700. I said how much are the adjusters, $600/side he said then labor for installation. I did a quick google for the parts, appears their attainable for a more lucrative price elsewhere.
Tell me what you know about height adjusters, diagnosing bad ones, and installing new ones + torsion bar adjustments if you dont mind. I cant get my techstream to work but I do have an Icarsoft and a set of 4 wheel scales if applicable. Thanks.

’03 LX470, then 19 years old and xxx,xxx miles or kilometres. If ‘globes’ are original, then likely they are past their best and replacement probably is in your future – not a difficult job. Test ‘globes’ per attachment – ideally this should be done at FSM-specified AHC pressures to be comparable with FSM numbers, but just do it to get some idea of overall condition of ‘globes’.

AHC operation, and AHC pressures tested on the stationary vehicle after raising from "LO" to "N" height, by themselves tell nothing about ‘globe’ condition. Vehicle can raise and lower normally and AHC pressures are related only to the share of vehicle weight carried by the AHC system versus share of vehicle weight carried by torsion bars and springs. Neither effect has anything to do with ‘globe’ condition. The raise/lower function and the AHC pressures tested on the stationary vehicle at "N" height would be the same even if the 'globes' were removed and replaced by a blank plate, or, if all the 'globes' had lost all nitrogen gas completely and filled with fluid (but then the system would be completely stiff -- fluid-locked -- and if the vehicle was driven there would be no damping through the Damping Force Control Actuator and extremely rough ride).

There are various possibilities but Front ‘harsh ride’ may be caused simply by excess front AHC pressure compared with FSM specification. This causes poor damping performance and ‘springy’ ride effect at "N" height. Fix by (1) ensuring that Front of vehicle is cross-level, and then (2) tightening torsion bars to increase the load they carry, reduce the load carried by AHC system – roughly 0.2 MPa reduction in AHC pressure per complete clockwise turn of both torsion bar adjusters.

Front and Rear Height Control Sensors -- if original, likely are worn and/or corroded internally – faulty Sensors may or may not give the relevant Diagnostic Trouble Codes (DTC’s C1711 at Front Right, C1712 at Front Left, C1713 at Rear) – did the Mechanic mention? Anyway, at this age, Height Control Sensors likely are past their best, regardless of absence of DTC’s, especially if long term driving conditions involved rain, snow and road salt. Replacement probably is in your future – also not a difficult job.

LC100/LX470 ‘Globes’ – Part Numbers:
Front LH & RH: 49141-60010
Rear LH & RH: 49151-60010

Toyota/Lexus Height Control Sensors – Part Numbers:
89405-60012 (Front Right)
89406-60022 (Front Left)
89407-60010 (Rear)

Aisin Height Control Sensors – Part Numbers:
HST-020 (Front Right)
HST-021 (Front Left)
HST-026 (Rear)

AVOID all other substitute Height Control Sensors.

Pricing at PartSouq Auto Parts Around the World - https://partsouq.com/ and IMPEX JAPAN — online new genuine spare parts shop - https://en.impex-jp.com/ are good places to start, with IMPEX currently best. Search “partsouq” and “impex” on IH8MUD for Members’ experiences with these suppliers. Then check local pricing.

See Post #15 (and earlier and later Posts at this thread) for further explanation about Height Control Sensors:

Intro and yet another AHC thread… - https://forum.ih8mud.com/threads/intro-and-yet-another-ahc-thread.1281317/#post-14403443

Browsing the information in this thread also may be helpful:

AHC Off Flashing. C1711 + C1776 - https://forum.ih8mud.com/threads/ahc-off-flashing-c1711-c1776.1282700/#post-14414634

The Search function will reveal more ....
 

Attachments

  • AHC - Cross level per FSM LoRes.pdf
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  • AHC HI-LO Test per FSM.pdf
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  • FSM Diagnostics AHC Height Control Sensors.pdf
    2 MB · Views: 13
Last edited:
Joined
Jul 16, 2020
Messages
48
Location
maine
’03 LX470, then 19 years old and xxx,xxx miles or kilometres. If ‘globes’ are original, then likely they are past their best and replacement probably is in your future – not a difficult job. Test ‘globes’ per attachment – ideally this should be done at FSM-specified AHC pressures to be comparable with FSM numbers, but just do it to get some idea of overall condition of ‘globes’.

AHC operation and AHC pressures tested on the stationary vehicle at "N" height by themselves tell nothing about ‘globe’ condition. Vehicle can raise and lower normally and AHC pressures are related only to the share of vehicle weight carried by the AHC system versus share of vehicle weight carried by torsion bars and springs. Neither effect has anything to do with ‘globe’ condition. The raise/lower function and the AHC pressures tested on the stationary vehicle at "N" height would be the same even if the 'globes' were removed and replaced by a blank plate, or, if all the 'globes' had lost all nitrogen gas completely and filled with fluid (but then the system would be completely stiff -- fluid-locked -- and if the vehicle was driven there would be no damping through the Damping Force Control Actuator and extremely rough ride).

There are various possibilities but Front ‘harsh ride’ may be caused simply by excess front AHC pressure compared with FSM specification. This causes poor damping performance and ‘springy’ ride effect at "N" height. Fix by (1) ensuring that Front of vehicle is cross-level, and then (2) tightening torsion bars to increase the load they carry, reduce the load carried by AHC system – roughly 0.2 MPa reduction in AHC pressure per complete clockwise turn of both torsion bar adjusters.

Front and Rear Height Control Sensors -- if original, likely are worn and/or corroded internally – faulty Sensors may or may not give the relevant Diagnostic Trouble Codes (DTC’s C1711 at Front Right, C1712 at Front Left, C1713 at Rear) – did the Mechanic mention? Anyway, at this age, Height Control Sensors likely are past their best, regardless of absence of DTC’s, especially if long term driving conditions involved rain, snow and road salt. Replacement probably is in your future – also not a difficult job.

LC100/LX470 ‘Globes’ – Part Numbers:
Front LH & RH: 49141-60010
Rear LH & RH: 49151-60010

Toyota/Lexus Height Control Sensors – Part Numbers:
89405-60012 (Front Right)
89406-60022 (Front Left)
89407-60010 (Rear)

Aisin Height Control Sensors – Part Numbers:
HST-020 (Front Right)
HST-021 (Front Left)
HST-026 (Rear)

AVOID all other substitute Height Control Sensors.

Pricing at PartSouq Auto Parts Around the World - https://partsouq.com/ and IMPEX JAPAN — online new genuine spare parts shop - https://en.impex-jp.com/ are good places to start, with IMPEX currently best. Search “partsouq” and “impex” on IH8MUD for Members’ experiences with these suppliers. Then check local pricing.

See Post #15 (and earlier and later Posts at this thread) for further explanation about Height Control Sensors:

Intro and yet another AHC thread… - https://forum.ih8mud.com/threads/intro-and-yet-another-ahc-thread.1281317/#post-14403443

Browsing the information in this thread also may be helpful:

AHC Off Flashing. C1711 + C1776 - https://forum.ih8mud.com/threads/ahc-off-flashing-c1711-c1776.1282700/#post-14414634

The Search function will reveal more ....
Thank you very very much!
 

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