Lx570 AHC issue

[highfructose]

Under sharp quick braking my 2011 lx570 with 80k miles (and an ahc fluid flush several months ago) shows an AHC fault…a brief yellow blip on the dash board that resolves itself.
Then today, I did a quick brake check coming towards a red light and the truck briefly read that it was in low height before righting itself again.
Any idea what’s going on? I can’t imagine the coils are soft and need replacing.

 

[99toylc]

What's the fluid level like?

 

[tbisaacs]

Would check the fluid level.

 

[highfructose]

What's the fluid level like?

Seems good to me. This is the level at neutral position.

for anyone who discovers this thread trying to do stuff to fluid: you have to put a flashlight behind the reservoir to make it illuminate and show the level…access it from around the spare tire.
Also the access port to see this view is behind the rear passenger tire.

 

[highfructose]

For anyone that discovers this thread via google trying to fix an issue: after a while of messing w ahc issues it seems that at least part of the problem was that I needed further bleeding of the system after the ahc fluid swap.

I’ve read that it may take as many as 6 bleed cycles to purge all the air from the system…I’ve done 4-5 bleeds and have noted a generally better more compliant ride.

Prior to ahc fluid swap I had a wallowy ride on the highway. Following the ahc swap I had a much tighter ride…but to the point of harshness/truck like ride…bleeding the ahc fluid (and putting it right back in the reservoir once it settled-it’s basically new and looks great) has gotten me back to what appears to be a more compliant ride.

I do not at this point know what the fluid sans air should look like…it comes out almost foamy during the first bleed each time…but that may just be due to the pressure of the fluid coming out of the orifice as I crack the bleeder, I do now know.

And, further, to assist you if you’re trying to troubleshoot your suspension, it appears there is a trouble shooting / diagnostic procedure for checking to see if your accumulator globes need to be replaced should an ahc fluid swap / flush not fully return your suspension to the quality you think it should be (attached).

There are clear instruction on replacement of accumulator globes within this forum.

 

[kwelhand]

For anyone that discovers this thread via google trying to fix an issue: after a while of messing w ahc issues it seems that at least part of the problem was that I needed further bleeding of the system after the ahc fluid swap.

I’ve read that it may take as many as 6 bleed cycles to purge all the air from the system…I’ve done 4-5 bleeds and have noted a generally better more compliant ride.

Prior to ahc fluid swap I had a wallowy ride on the highway. Following the ahc swap I had a much tighter ride…but to the point of harshness/truck like ride…bleeding the ahc fluid (and putting it right back in the reservoir once it settled-it’s basically new and looks great) has gotten me back to what appears to be a more compliant ride.

I do not at this point know what the fluid sans air should look like…it comes out almost foamy during the first bleed each time…but that may just be due to the pressure of the fluid coming out of the orifice as I crack the bleeder, I do now know.

And, further, to assist you if you’re trying to troubleshoot your suspension, it appears there is a trouble shooting / diagnostic procedure for checking to see if your accumulator globes need to be replaced should an ahc fluid swap / flush not fully return your suspension to the quality you think it should be (attached).

There are clear instruction on replacement of accumulator globes within this forum.

View attachment 2963689

How much fluid you have to bleed from each bleeding port in order to get rid of all air?
If you do 6 bleeding intervals, then do you bleed all 4 ports and how many miles apart?

 

[highfructose]

How much fluid you have to bleed from each bleeding port in order to get rid of all air?
If you do 6 bleeding intervals, then do you bleed all 4 ports and how many miles apart?

Hopefully someone that knows better than I will respond. However, I bled as much as 16 oz on each corner using this bottle. Usually only the first one I bleed (driver side front) gives me all that fluid…dunno why. Probably it’s sucks a little from the other side. Maybe mine still has air over there though. Ahc is still kind of Byzantine to me. Simple to mess with, not entirely clear how to make sure it’s perfectly set up following maintenance/repair.

I bled the ports…then cycled the truck into normal low normal and low again (which it was slow and goofy doing, honestly)…then did the same again several times.

Then took it for a short drive…then bled just the drivers side front 1-2 more times.

Honestly I don’t know what “bubbles” people are talking about so I’m just repeatedly bleeding and hoping the ride improves lol.

I’ll probably try to “test” the system’s accumulator globes using the scorings/markings/dashes on the back of the reservoir today-I need to drop the spare tire anyway so I might as well see if there a way to see the reservoir markings and attempt a diagnostic.

All that said, there does seem to be a marked improvement after these multiple bleed cycles.

Doing my ahc fluid swap a couple thousand miles ago I did let the reservoir get too empty and heard some grinding coming From the pump. So for all I know I was pumping air in during that which later required, unbeknownst to me, several more bleed cycles to remove.

I’m not a mechanic and I often learn mechanicking via purchasing parts I moronically broke. Nothing comes for free. Mechanicking costs money to learn one way or the other.


Mission Automotive 16oz Brake Bleeding Kit - Easy Use One Person Brake Fluid Bleeder with Magnet Mount and Hanging Lanyard - for Car and Motorcycles Brake Systems 16oz Fluid Capacity Amazon product ASIN B07L52B4CX

 

[TeCKis300]

Glad you kept attacking this and were able to find some resolution. Moreso, provide feedback as to symptoms and lessons learned. As these things get older, others will surely benefit from the knowledgebase and hivemind here.

Hopefully that was it and the system will earn your confidence back.

 

[lx200inAR]

There are markings on the opposite side of the tank from the inspection panel as well. But the most markings or graduations are on the rear of the tank. When i attempted to see if i had 5 lines, it was difficult to get a good line of where the fluid was. Maybe i could have tried harder with a brighter light.

I probably need to bleed mine more aggressively like you have. I believe my pump took in air when it was low on fluid and went into AHC extra high. My fronts seem to not drop too much of the "chocolate milk" fluid when i bleed, but the rears will let out quite a bit.

Tank rear

Tank inspection window on left side.

 

[kwelhand]

Whoever designed the location of that AHC reservoir should be punished.

 

[04UZJ100]

Whoever designed the location of that AHC reservoir should be punished.

Or thanked. Lots of 100 AHC systems killed because of accidental/ignorant addition of brake fluid to the reservoir.

 

[kwelhand]

Or thanked. Lots of 100 AHC systems killed because of accidental/ignorant addition of brake fluid to the reservoir.

Right… it does look like a brake fluid reservoir on LX470.

 

[highfructose]

After doing some ahc fluid bleeds, the ride improved considerably.

Yesterday I noted that the ride was a bit rougher again. I checked and the vehicle had settled/leaned to the driver side like it often does.

Regardless of ahc sensor height, over the course of a day or less, the vehicle will droop. The driver side front fender will be between 1.5” and 2” lower than passenger side.

Currently my suspicion is that the right rear spring, being taller/stiffer to counter the fuel tank has, over time, wore out the left front.

When I bump the suspension up to high and then back to normal it no longer leans for a period of time…and the ride improves.

So if you’ve dealt with similar issues, a replacement coil at least on the driver front may be in order.

If all goes according to plan, I will replace both front coils…as well as putting a “right rear” coil on the left rear. I’m hoping this will keep the vehicle from leaning by allowing the shocks, left to right, to equalize pressure without resulting in a disparity of “pressure” due to a weak spring.

 

[TeCKis300]

After doing some ahc fluid bleeds, the ride improved considerably.

Yesterday I noted that the ride was a bit rougher again. I checked and the vehicle had settled/leaned to the driver side like it often does.

Regardless of ahc sensor height, over the course of a day or less, the vehicle will droop. The driver side front fender will be between 1.5” and 2” lower than passenger side.

Currently my suspicion is that the right rear spring, being taller/stiffer to counter the fuel tank has, over time, wore out the left front.

When I bump the suspension up to high and then back to normal it no longer leans for a period of time…and the ride improves.

So if you’ve dear with similar issues, a replacement coil at least on the driver front may be in order.

If all goes according to plan, I will replace both front coils…as well as putting a “right rear” coil on the left rear. I’m hoping this will keep the vehicle from leaning by allowing the shocks, left to right, to equalize pressure without resulting in a disparity of “pressure” due to a weak spring.

I can't say for sure, but I'd be highly suspicious of globe/accumulator failure rather than springs. The behavior you're describing is not exactly common or normal? And I don't recall anyone that's actually had to replace springs to fix something. It could be that an accumulator has failed and is not provide enough compliance. The the fluid is being forced through some bypass that frothing the fluid? Could also be contamination effecting an internal valve somewhere causing things to bleed down? I'm making some of this up but that's my hunch.

 

[highfructose]

I can't say for sure, but I'd be highly suspicious of globe/accumulator failure rather than springs. The behavior you're describing is not exactly common or normal? And I don't recall anyone that's actually had to replace springs to fix something. It could be that an accumulator has failed and is not provide enough compliance. The the fluid is being forced through some bypass that frothing the fluid? Could also be contamination effecting an internal valve somewhere causing things to bleed down? I'm making some of this up but that's my hunch.

Yes. If coils don’t do the trick, on the accumulators…and then maybe more.

Worst case scenario I completely replace my suspension and have a new suspension.

 

[kwelhand]

Why don't you do the accumulators first?
I believe the accumulators are one of the most important components of AHC system along with fresh fluid.
If nothing happens, then do the front shock/ coils?
You can get 4 OEM accumulators directly from Japan under $500 shipped.

 

[highfructose]

Why don't you do the accumulators first?
I believe the accumulators are one of the most important components of AHC system along with fresh fluid.
If nothing happens, then do the front shock/ coils?
You can get 4 OEM accumulators directly from Japan under $500 shipped.

When I bump the vehicle into high and then back into normal, the vehicle no longer leans…and the ride is quite nice.

I was told that it may be the case that since the ahc shocks like to have equal pressure left to right, that a weak spring could cause the system to “want” to lean.

It made sense that it could have a weak spring in the front left because the right rear spring is taller/stiffer than all the rest…so over time that places more weight on the opposite spring…which can degrade the spring over time, logically, producing the symptom I’m seeing.

I came across, I think, a full set of 4 brand new coils for $180 and I was already planning on adding spacers to the front so I figured what the heck, while I’m in there messing with spacers, I might as well put brand new coils on too.

When I get time I’m going to do the diagnostic (checking the hash marks/dashes on the reservoir) on the accumulators…and if it indicates a need for replacement, I’ll replace them.

 

[kwelhand]

When I bump the vehicle into high and then back into normal, the vehicle no longer leans…and the ride is quite nice.

I was told that it may be the case that since the ahc shocks like to have equal pressure left to right, that a weak spring could cause the system to “want” to lean.

It made sense that it could have a weak spring in the front left because the right rear spring is taller/stiffer than all the rest…so over time that places more weight on the opposite spring…which can degrade the spring over time, logically, producing the symptom I’m seeing.

I came across, I think, a full set of 4 brand new coils for $180 and I was already planning on adding spacers to the front so I figured what the heck, while I’m in there messing with spacers, I might as well put brand new coils on too.

When I get time I’m going to do the diagnostic (checking the hash marks/dashes on the reservoir) on the accumulators…and if it indicates a need for replacement, I’ll replace them.

Looks like you’re all set!
Keep us updated with your progress and findings!

 

[tacoduck]

I’ll just add that my lx470 had 310k miles on original ahc globes. It’s a robust and proven system.