Height sensor dead in 05LX (1 Viewer)

[STEVEN XU]

I am really got burnt by the AHC. My 05 LX got 2 accumulators replaced in 2007 while it was at 40k mile. I drove it to LEXUS dealer to check AHC last week after I couldn't bear the bouncy. The LEXUS mechanic printed out the diagnose. It said that code of c1760/c1776 were detected and need to replace LH front height sensor to fix the problem. if I like to pay $600.
I trust the competence of that lexus mechanic who replaced the accumulators for me two years ago. His diagnose could be accurated. But I put the repair on hold in order to figure out what is going on with the freaky AHC in LC/LX which screw up the customers mostly and TOYOTA seems haven't done anything about it.
I removed the fault height sensor and disassemble it by myself. Oh a wholely crap, a spring is rotted out and no closed circuit in the sensor at all. That is for sure I need to replace or repair the fault sensor. But the question mark on my head is how can that sensor break like that since my rig merely 4yrs old and with 6ok on it plus no off-load at all( but heavy snow in winter in the area I live). Could be another two height sensor got broken? I am going to inspect them soon. and I will feedback the inspection.
One thing puzzle me is that c1776 depicts FRONT WHEEL SPEED SENSOR SIGNAL, how does it relate to AHC fault in my case. By the way, c1760 depicts ABNORMAL OIL PUMP PRESSURE.Any help for explaining the rationality would be appreciated.

 

[Dutchy]

Just heard today all three of my sensors are broken according to the diagnose system of toyota. I can get second hand settings but i am now really doubting the system. I mean 3 sensors broken at once???

Will cost me a 1000 us to get them all replaced. I dunno i think im gonna get rid of the system.... heard one to many stories about not working a 100 procent.

I am leaning over to a full replcement with other shocks... question is... wich ones will give me a descent lift and keep some of the comfort in the ride.

sorry for the hijack... but i feel your missery..

 

[Jim_Chow]

The newer sensors aren't as robust as the older ('98-04) ones (toyota reportedly changed suppliers). Owners have had the old sensors last for years w/o issues. Salt is the only thing that kills the old sensors. You can replace the entire LX suspension (front t-bars, rear coils, rear sway bar and bushings, shocks) w/ non-AHC OEM parts for around $1200 plus labor.

 

[STEVEN XU]

Checked the remaining 2 H-Sensors, they were fine.

 

[STEVEN XU]

Some pic for the broken height sensor

LH side height sensor for 05LX.

 

[STEVEN XU]

Dutchy
You can verify whether the height sensor dead or not by checking the resistance between the 3 terminal pins. If the resistance is around 1k to 3.5k between each two pins and the value vary quickly following the position change of the swing arm, it will be OK. Some DIY hints: Opening up the sensor cover, clean up moisture or replace the broken parts inside, ( I chop a piece of spring to replace the rotted original one), check the resistance OK, put it back to the vehicle. There are some useful posts about the sensor removal in this site as well.

 

[uHu]

Steven, I've seen many bad position-potentiometers, your's is not the worst. But normally, at this state, they are exchanged.
Doesn't look hopeless though.

Three issues to solve:
1
If the connection from the plug to the bottom of the contact-springs is OK, you could source replacement springs for contact from the plug to the carbon trace.
2
The carbon trace in the lid must be complete and unbroken. (think it is 5 k ohm)
3
The spring has to have good contact points. On your pic it looks like the points might be corroded away.

For making the sensor last longer, to keep moisture out, it might be enough to add a thick aluminium lid over the normal lid, as i've seen the lid is not rigid enough to close all the way between the screws. The screws would have to be longer as well then.

Good luck, and keep us posted.

 

[STEVEN XU]

Thanks for help from all of you. I have installed a good height sensor back to the truck. But the ride is still bouncy as before. I've done a couple of tests in order to confirm AHC working properly.
1. Raised the truck from LO to HI and found reservoir level change more than 7 graduation;
2. Height can been changed flawlessly among HI,N,LO;
3. Trickle sound can been heard as ignition being on. I pretty get used to that sound while AHC pump is working. Assume pump is working well.

I am wondering whether I should reset the DTC after I put the good Height Sensor back on. Any suggestion?

 

[uHu]

Thanks for help from all of you. I have installed a good height sensor back to the truck. But the ride is still bouncy as before. I've done a couple of tests in order to confirm AHC working properly.
1. Raised the truck from LO to HI and found reservoir level change more than 7 graduation;
2. Height can been changed flawlessly among HI,N,LO;
3. Trickle sound can been heard as ignition being on. I pretty get used to that sound while AHC pump is working. Assume pump is working well.

I am wondering whether I should reset the DTC after I put the good Height Sensor back on. Any suggestion?

More than 7 grads' - How much more?
This actually measures how much gas there is to compress, in the 4 spheres together.
With 4 flat spheres you get a bit less than 7 notches (still more than 5)
With 4 new spheres you get at least 14.
So with 2 new ones you will always get more than 7, even if the other 2 are flat.

Which 2 were replaced? & Which end is bouncy now?

 

[STEVEN XU]

More than 7 grads' - How much more?
This actually measures how much gas there is to compress, in the 4 spheres together.
With 4 flat spheres you get a bit less than 7 notches (still more than 5)
With 4 new spheres you get at least 14.
So with 2 new ones you will always get more than 7, even if the other 2 are flat.

Which 2 were replaced? & Which end is bouncy now?

Thanks uHu.
It is 8 graduations in level variation as from Hi to Lo.
The vehicle rebound evenly. I couldn't find any difference between the front and the rear.
Both FR and FL nitrogen spheres were replaced two years ago. I initially guessed the two spheres in the rear might go flat this time. But they don't.( That's what the lexus mechanic tell me)

 

[STEVEN XU]

AHC problem had been fixed

Thanks uHu.
It is 8 graduations in level variation as from Hi to Lo.
The vehicle rebound evenly. I couldn't find any difference between the front and the rear.
Both FR and FL nitrogen spheres were replaced two years ago. I initially guessed the two spheres in the rear might go flat this time. But they don't.( That's what the lexus mechanic tell me)

Two rear sphere accumulators had been replaced. They went flat and no long absorbed any shock. There are 12 graduations in reservoir level change now as from HI to LO. The ride is wonderful.
Lesson learned from this event is that reservoir level might have 7 graduation change with the accumulator arrangement of 2 new /2 flat.

 

[agaisin]

where do you guys get the replacement springs from?

 

[STEVEN XU]

Bought a clothing clip in hardware store. Got the spring by disassembling it.

 

[tom.]

with different settings on sensors and t-bars, there are different reservoir level changes. I am getting from 8 to 14 on 4 new spheres.