AHC issues - rear is high and front is slammed low (1 Viewer)

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Joined
Apr 28, 2022
Threads
5
Messages
25
Location
Sacramento, CA
On the way home from the mountains (snow+grit) I noticed the ride getting progressively bumpier. Something definitely seemed wrong with the suspension and upon exiting the car I noticed that the front is basically slammed with hardly any clearance between the tire and the fender while the rear seems to be quite high.

The whole car basically looks like it's butt is in the air - see attached photos. I can only attach 5 pictures here, so I'll attach the rest in a follow-up comment but the AHC fluid seems to be in a reasonable position and there is no code in tech stream.

The AHC lights would blink H or L when trying to raise or lower the car, but nothing would happen. Though when I hooked up TIS I see OFF under the height position lights.

TIS is reporting (see screenshot in next comment):

FR Height Control Sensor-2.9 inch
FR Height Control Sensor6.0 inch
RR Height Control Sensor1.6 inch
Front Pressure Sensor0.0 Mpa-g
Rear Pressure Sensor0.0 Mpa-g
Accumulator Pressure Sensor0.0 Mpa-g

-----

My guess was going to be that this is a height control sensor issue, but I'm thrown off by the 0.0 for the pressure sensors and not sure where I should start.

The car is a 2003 LX470 with ~260,000 miles which I purchased about 12,000 miles ago. The car has been through a few owners so I only have partial maintenance records and I can't find anything in them to indicate any service having been done to the AHC system. I'm not opposed to spending the money to rebuild whatever needs to be done - sort of the gamble when you get a $10,000 LC100 and we've been setting money aside accordingly. If it makes sense to do new accumulators and fluid I've seen some videos on that, but I'm not sure how to make sure the sensors and pump are in good working order or anything else I might be missing.

All help is much appreciated, thank you!

Front Left:
0-FL.jpg


Front Right:
1-FR.jpg


Rear Left:
2-RL.jpg


Rear Right:
3-RR.jpg


Stance:
4-Stance.jpg
 
I always like to start with the simplest and easiest things to get at, and look at.

The arm that connects the hight control sensor to the adjustable link, over the years they rust through and drop off, also the adjustable link can cause problems, like rusting and seizing.

There are plenty of excellent post on here about all aspects to do with AHC maintenace and breakdowns.

Just for example, take a look at PADDO's posts
 
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Jacked up the car and found a broken ride height sensor. Went ahead and bought a set of 3 and will go ahead and replace them all. Not sure what would cause it to shear like that, but it's pretty old so not completely surprising I guess.

8-Sensor.jpg
 
Jacked up the car and found a broken ride height sensor. Went ahead and bought a set of 3 and will go ahead and replace them all. Not sure what would cause it to shear like that, but it's pretty old so not completely surprising I guess.

View attachment 3214027
Heads up: aftermarket sensors are complete garbage. Hopefully you bought genuine Toyota/Lexus or Aisin. For some reason, the aftermarket sensors for this part continue to be reported as nearly 100% failures - if not immediately then within a short period of time.

Good find on the arm. Anytime you see those height readings differing from reality you know the sensor or wiring is to blame. The pressure readings are only "live" when the system can successfully move heights. If it can't achieve N or H, it will not report pressures - even if it is pressurized.
 
Thank you - I'm pretty novice for maint. stuff so hopefully this fixes the issue. I bought an OEM set from partsouq - I got other parts from them before and seemed to be legit but yeah they're like 5x the price of the aftermarket sensors.

I think it was $230 for each (x3) compared to like $40 for the amazon special. I'm also eyeing a set of globes from impex .. even though I think the arm is the issue, it's probably high time to do a flush and may as well do the globes if they're original. Though the height sensors cost more ($290x3) on impex vs partsouq.

The pressure readings are only "live" when the system can successfully move heights. If it can't achieve N or H, it will not report pressures - even if it is pressurized
Very interesting, didn't know this thanks!


Parts list if it's helpful for others:
49141-60010 TOYOTA ACCUMULATOR, FR
49151-60010 TOYOTA ACCUMULATOR, RR
89407-60010 SENSOR SUB-ASSY, HEIGHT CONTROL, REAR
89405-60012 SENSOR SUB-ASSY, HEIGHT CONTROL, FRONT RH
89406-60022 SENSOR SUB-ASSY, HEIGHT CONTROL, FRONT LH
08886-81221 LEX-SUSPENSION FLUID 1Q (or)
08886-01805 LEX-SUSPENSION FLUID 2.5L
 
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Thank goodness I found this thread. My vehicle did the same thing after I hit a large pothole.
I floundered around for a while troubleshooting and testing the pump and relay with everything working. Decided to change the front globes after I found no fluid when I bled the front LH globe and very little fluid came out with no pressure from the front RH globe. Nothing I did made a difference.

Sure enough my front LH height sensor was broken just like yours. I'm waiting for a replacement and will see what next I have to do.
 
Glad it helped - I ended up changing the globes eventually and replaced the front left sensor to replace my broken link. I got the globes from impex and the fluid and ride height sensors from partsouq.

If you haven't gotten one already, the data cable to run techstream is an absolute life saver.
 
Thank goodness I found this thread. My vehicle did the same thing after I hit a large pothole.
I floundered around for a while troubleshooting and testing the pump and relay with everything working. Decided to change the front globes after I found no fluid when I bled the front LH globe and very little fluid came out with no pressure from the front RH globe. Nothing I did made a difference.

Sure enough my front LH height sensor was broken just like yours. I'm waiting for a replacement and will see what next I have to do.
I replaced the broken sensor and all is well at the moment. I while waited for the part, I read where I could disconnect the sensor and the AHC would level out and go to "off". Sure enough that got me back in business until I replaced the sensor. Next step is to bleed the system.
 

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