Lexus LX 470 Suspension Issues Explained(+5 Top Issues with Pro Tips)

In this brief article we are going to discuss the Lexus LX 470 suspension issues, what the causes are, and how these issues can be effectively dealt with.

Top 5 Suspension Problems in the Lexus LX 470

The 5 most common Suspension Problems in the Lexus LX 470 are:

  • AHC (Active Height Control) Unable to lift the vehicle to “HI” setting from ‘N’
  • Bouncy Ride
  • AHC always in ‘LO’ and not moving to ‘N’ position
  • AHC does not change height & AVS does not change mode
  • Leaking Shock Absorber

What suspension does the 100 series Toyota Land Cruiser have?

The Land Cruiser 100 Series or J100 platform (also known as Lexus LX 470 in North America), had a ‘Torsion Bar’ spring in the front suspension and Coil Spring Multi-link Rear suspension.

Apart from the above standard set-up, there were optional advanced features like :

  • KDSS (Kinetic Dynamic Suspension System)
  • AHC (Active Height Control) &
  • TEMS (Toyota Electronic Modulated Suspension)

What are the common problems with the LX 470 Suspension?

The most common suspension problems with the LX 470 are:

AHC (Active Height Control) Unable to lift from ‘N’ to ‘HI’

Symptoms:

  • When the vehicle is already in ‘Lo’ and ‘N’ is selected,  the AHC manages to raise. Lowering from ‘N’ to ‘Lo’ also functions.
  • When trying to move to the ‘Hi’ position, the suspension moves only by a minuscule amount.

Root Cause:

  • The Gas pressure/Fluid pressure seems to not develop beyond the ‘N’ position. There could be 3 possible reasons:
  • Similar to the Brake System, over a long usage period, there could be minor depletion of AHC Hydraulic system fluid. 
  • The “Gas Chamber” connected to the Height Accumulator may be malfunctioning
  • Either one or more of the 4 Height Sensors, located at each suspension corner, might be malfunctioning

Solution:

  • Check the Fluid level in the reservoir under the hood. If needed top-up with the OEM provided AHC fluid. Repeat the exercise of trying to select ‘Hi’ and seeing if the vehicle lifts itself.
  • In case the earlier measure did not work, then, Replace the “Gas Chamber” and check if the AHC functions.
  • In case the “Gas Chamber” replacement did not fix the issue, then try to either recondition or replace the “Height Sensors”

Bouncy Ride

Symptoms:

  • Ride quality seems bouncy even for very minor bumps
  • Shock-absorbers seems normal/newly replaced

Root Cause:

  • The vehicle suspension lift happens when the AHC Control system signals the “Gas Chamber and Damping Force Control Actuator” to increase the Nitrogen gas pressure in the Shock Absorber, leading to an increase in Shock Absorber length. So, normally the Shock-absorber would have been the first to blame. 
  • Since the shocks were already verified as properly working, the fault would most likely be with the “Gas Chamber” which ‘HOLDs’ and maintains the Gas Pressure. The Gas Chamber contains a membrane that produces pressure and this deteriorates due to wear and tear.

Solution:

  • Replace all 4 of the Gas Chambers after releasing the hydraulic pressure and bleeding the system. Once fitted, the system will need to be replenished with new Hydraulic Fluid and bleeded to eliminate air bubbles ( similar to brake hydraulics). 

AHC always in ‘LO’ and not moving to ‘N’ position

Symptoms:

  • The vehicle sits at the ‘Lo’ position alone
  • When selecting either the ‘N’ or ‘Hi’ position, the suspension does not change in height at all

Root Cause:

  • In the AHC system, there are 4 sensors located at each of the vehicle corner suspensions. These sensors signal the control system as to the current position of the Ride Height (‘H’, ‘N’ or ‘L’). Every time you select and change the Ride height, these sensors are crucial to the functioning of the AHC. 
  • If your vehicle has crossed 100k miles then there is a good possibility that these Sensors might be malfunctioning. The Sensor is an assembly consisting of moving parts coupled with Electronics, so there is a possibility that the contacts might be dirty.

Solution:

  • For those who are not much into DIY, replacing these components would be the first choice.
  • But for those DIY people, there is one way to avoid replacing the sensor. You could dismantle and rebuild this assembly. It would be suggested to use ‘Brake Fluid’ for cleaning the individual small parts.

AHC does not change height & AVS does not change mode

Symptoms:

  • Vehicle stays in ‘L’ ride height position
  • The AHC ‘off’ lamp blinks and the ‘L’ lamp is illuminated constantly. 
  • Pressing the AHC ‘off’ button does not change anything.
  • Changing the AVS suspension mode from comfort to sport makes no difference in feel. The suspension shock absorbers are stuck in a very stiff setting

Root Cause:

  • Use a scanner to check for Fault Codes.
  • The most probable errors you may get are : c1751 (continuous current to compressor) and c1762 (abnormal oil pressure to pump)
  • This clearly indicates a probable issue with the pump
  • You can check the pump by removing the control system connector and attaching a jumper wire into the diagnostics connector of the pump to manually test-run the AHC pump. If it does not manage to move any liquid, then it is clear that the pump is one of causes
  • You can also inspect the shock-absorbers for any oil stains and test the ‘Gas Chambers’ for pressure

Solution:

  • After inspecting the components mentioned above, start replacing the ones that were damaged/malfunctioning

Leaking Shock Absorber

Symptoms:

  • The Ride height may be either partially working or completely not working
  • Excessive bouncing during driving and doing a ‘Bounce’ test
  • Oil Stains on the Shock bottom tube

Root Cause:

  • Over time, the shock absorber seals and valves wear out due to ageing of Rubber/Polymer wear parts

Solution:

  • Shock absorber replacement with OEM part

Conclusion

In this brief article we have discussed the Lexus LX 470 suspension issues, what the causes are, and how these issues can be effectively dealt with.

Frequently Asked Questions (FAQs): 

 

How many miles can a Lexus LX470 last?

On an average, you could expect a life of between 300,000 and 500,000 miles.

Is LX470 a good car?

Yes, the LX 470 is a fine example of Automotive engineering and a great car. The Lexus LX 470 is built on the Land Cruiser’s heritage of toughness, combined with interior comforts and advanced safety and comfort features like KDSS, AHC and TEMS

When did Lexus stop making the LX470?

The LX 470 was the second generation of the Lexus LX line produced between 1998 and 2007.

What year lx470 is the best?

The Lexus LX 470 had several upgrades done to it throughout its product life cycle. In the used market the LX 470’s model years 2003 onwards seem to be the best.

 

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