AHC failure only after flush (1 Viewer)

[AClarko]

Just picked up a 2000 LX470 with 142k mi. There were not records of the AHC fluid being flushed in the past. The fluid was a little low in the reservoir and dark in color.

Before the flush I performed the health test, but first I added some AHC fluid to get it to the right level in the reservoir. I had about 7-8 ticks on the reservoir between HI and LO height settings.

I dropped the vehicle to the lowest setting, shut it off and used an extractor to empty the reservoir. I filled the reservoir up with 2L of fresh AHC. When I turned the car on it raised to Normal height no issues. I shut the car off in N and proceeded to bleed the driver side accumulator, not much fluid came out and it stopped on its own some of it was white. I was under the impression that the car should have lowered. This is where I think I made a mistake.

From there I think I should have turned the car back on. I didn't. I went to bleed the front driver side actuator, it bled, the car lowered and I closed it. If I am recalling correctly the fluid stopped before I closed it.

This is where I went to turn the car on to lift the car back up and continue the process to drain the other 3 actuators..but boom it would not lift back up. It stayed bottomed out after the bleed. You can hear a whine for about 30-60 seconds then it stops and the height control "OFF" button flashes.

Sounds like I screwed something up. The system worked before through the 3 height settings now it doesn't. I took it to lexus and they said my pump is shot, I just find this a little coincidental. $5000 quote from lexus just for the pump, and he said then I may need new globes etc after so looking at $7000, he recommended I just go with an Ironman kit.

So did I screw up the process? Anything I can do to try to revive this or should I just convert to conventional?

The driver side front sat about .5 inches lower and the dampening seemed poor for the car before I did any of the flushing but the system did "work".

Thank you for any help.

 

[xplore]

If the fluid stopped coming out before you closed the bleeder valve, it sounds like you might have run it out of fluid. I'm not AHC expert, but it seems like a basic hydraulic system similar to your brakes. You have to keep topping off the fluid in the reservoir during the bleeding procedure. Were you checking on that and topping it off as you went?

Even if the pump is toast, there are so many people replacing their AHC systems that there are a lot of good used parts out there for relatively cheap. I wouldn't buy that part new if I was you.

 

[suprarx7nut]

Just picked up a 2000 LX470 with 142k mi. There were not records of the AHC fluid being flushed in the past. The fluid was a little low in the reservoir and dark in color.

Before the flush I performed the health test, but first I added some AHC fluid to get it to the right level in the reservoir. I had about 7-8 ticks on the reservoir between HI and LO height settings.

I dropped the vehicle to the lowest setting, shut it off and used an extractor to empty the reservoir. I filled the reservoir up with 2L of fresh AHC. When I turned the car on it raised to Normal height no issues. I shut the car off in N and proceeded to bleed the driver side accumulator, not much fluid came out and it stopped on its own some of it was white. I was under the impression that the car should have lowered. This is where I think I made a mistake.

From there I think I should have turned the car back on. I didn't. I went to bleed the front driver side actuator, it bled, the car lowered and I closed it. If I am recalling correctly the fluid stopped before I closed it.

This is where I went to turn the car on to lift the car back up and continue the process to drain the other 3 actuators..but boom it would not lift back up. It stayed bottomed out after the bleed. You can hear a whine for about 30-60 seconds then it stops and the height control "OFF" button flashes.

Sounds like I screwed something up. The system worked before through the 3 height settings now it doesn't. I took it to lexus and they said my pump is shot, I just find this a little coincidental. $5000 quote from lexus just for the pump, and he said then I may need new globes etc after so looking at $7000, he recommended I just go with an Ironman kit.

So did I screw up the process? Anything I can do to try to revive this or should I just convert to conventional?

The driver side front sat about .5 inches lower and the dampening seemed poor for the car before I did any of the flushing but the system did "work".

Thank you for any help.

Good lord, dealers are dumb. Please do me a favor and send them some version of this information.

The pump is not dead.

The pump is not $5000 - not even close. Globes are not an additional $2000. Of that $7000 quote, roughly $6000 is split between labor and dealer profit margin. Almost all is dealer profit margin.

Even if the pump was dead (it almost certainly is not) the pump is $321.66 at local dealers to St Louis and $465.23 MSRP from Toyota. See below. Labor is a few hours at most. $5k is an insult and a sign they're scared of the job.

This sort of thing (loud pump and failure to raise) happens a lot with failed bleeds. Many folks bleed successfully, but naturally we hear more about the failures. I suspect people are letting the reservoir run dry, although 2L in the reservoir should make that unlikely. I digress...

A loud pump generally means the pump is moving a mixture of gas and liquid. If the pump ran well before, we can be relatively certain that air was introduced into the system during the bleed process. Therefore, we can be relatively certain the fix is a proper bleed to get that air out.

Tip: Only bleed from L. Do not bleed from N. This reduces the quantity of fluid moved per cycle and helps you avoid running dry. Bleed the accumulator last. The "Paddo" method is a favorite here and my recollection is this:

1. Start car. Move to N if not already there. If you cannot raise to N, that's alright. Let it run for at least 90 seconds after any height change to ensure the accumulator gets charged.
2. Using a well sealing hose over the bleeder, crack open the passenger front. As soon as flow stops, close that bleeder. Pay *very* close attention to the fluid moving out of the bleeder. It should be perfectly liquid. If there are ANY bubbles or slugs of air, that bleeder port needs additional bleed cycles after you complete this one. Lots of bubbles from only one port can signify a dying membrane of that component and is a great clue telling you to replace said component.
3. Bleed Driver Front.
4. Inspect reservoir. Ensure it is filled at LEAST to the max line, ideally more than that.
5. Start vehicle. Allow 90 seconds to raise back up to N, if the car allows, then lower to L. Let car idle for at least 90 seconds and listen for the pump running. Once pump stops and at least 90 seconds have passed, turn car off. Inspect fluid level. Top off as needed to keep it well above max.
6. Bleed passenger rear followed by driver rear.
7. Check fluid level (should be the same as step 5, well above Max).
8. Start the car and allow system to raise to N and charge accumulator. Lower to L.
9. Turn off engine.
10. Bleed accumulator.
11. Check fluid level.
12. Start and allow to charge accumulator and verify fluid level.

If the pump will not run for very long and you get a blinking AHC light, it means you have an error code. Most likely you have the code for abnormal pressure - indicating the system has some air in this case and therefore the pump cannot build pressure. One recent tip I recommended with some success recently is to crack the output line from the pump block. Do this with the car off and use extreme caution. The goal is to let out any trapped air from that pump output line that would otherwise be annoying to bleed since the pump refuses to run.

Let us know how it goes. These are always fun challenges for me. The dealers are ... hmmm... so hard to put it in a non-offensive term. Let's say ignorant and/or opportunistic.

Converting to conventional is an objective downgrade in quality. AHC is more complicated, but a superior system. If you're willing to get the bleed figured out and do some basic and infrequent upkeep, AHC is quite reliable.

 

[Rebus Knebus]

The accumulator only holds a few hundred ml and bleeding the accumulator will NOT lower the vehicle, so that part of your flush sounds fine.

 

[DBULL]

It seems that the bleeders are being left open far to long allowing air to enter the system.Once it gets in,it naturally rises to the highest point,that being the pump itself.Slowly cracking the line exiting the pump will let air escape and gravity should allow fluid to replace that air.The bleeder screws on this system are a somewhat odd diameter making it difficult to get a plastic hose to seal and that possibly adds to the problem.

 

[AClarko]

Good lord, dealers are dumb. Please do me a favor and send them some version of this information.

The pump is not dead.

The pump is not $5000 - not even close. Globes are not an additional $2000. Of that $7000 quote, roughly $6000 is split between labor and dealer profit margin. Almost all is dealer profit margin.

Even if the pump was dead (it almost certainly is not) the pump is $321.66 at local dealers to St Louis and $465.23 MSRP from Toyota. See below. Labor is a few hours at most. $5k is an insult and a sign they're scared of the job.

View attachment 2816622


This sort of thing (loud pump and failure to raise) happens a lot with failed bleeds. Many folks bleed successfully, but naturally we hear more about the failures. I suspect people are letting the reservoir run dry, although 2L in the reservoir should make that unlikely. I digress...

A loud pump generally means the pump is moving a mixture of gas and liquid. If the pump ran well before, we can be relatively certain that air was introduced into the system during the bleed process. Therefore, we can be relatively certain the fix is a proper bleed to get that air out.

Tip: Only bleed from L. Do not bleed from N. This reduces the quantity of fluid moved per cycle and helps you avoid running dry. Bleed the accumulator last. The "Paddo" method is a favorite here and my recollection is this:

1. Start car. Move to N if not already there. If you cannot raise to N, that's alright. Let it run for at least 90 seconds after any height change to ensure the accumulator gets charged.
2. Using a well sealing hose over the bleeder, crack open the passenger front. As soon as flow stops, close that bleeder. Pay *very* close attention to the fluid moving out of the bleeder. It should be perfectly liquid. If there are ANY bubbles or slugs of air, that bleeder port needs additional bleed cycles after you complete this one. Lots of bubbles from only one port can signify a dying membrane of that component and is a great clue telling you to replace said component.
3. Bleed Driver Front.
4. Inspect reservoir. Ensure it is filled at LEAST to the max line, ideally more than that.
5. Start vehicle. Allow 90 seconds to raise back up to N, if the car allows, then lower to L. Let car idle for at least 90 seconds and listen for the pump running. Once pump stops and at least 90 seconds have passed, turn car off. Inspect fluid level. Top off as needed to keep it well above max.
6. Bleed passenger rear followed by driver rear.
7. Check fluid level (should be the same as step 5, well above Max).
8. Start the car and allow system to raise to N and charge accumulator. Lower to L.
9. Turn off engine.
10. Bleed accumulator.
11. Check fluid level.
12. Start and allow to charge accumulator and verify fluid level.

If the pump will not run for very long and you get a blinking AHC light, it means you have an error code. Most likely you have the code for abnormal pressure - indicating the system has some air in this case and therefore the pump cannot build pressure. One recent tip I recommended with some success recently is to crack the output line from the pump block. Do this with the car off and use extreme caution. The goal is to let out any trapped air from that pump output line that would otherwise be annoying to bleed since the pump refuses to run.

Let us know how it goes. These are always fun challenges for me. The dealers are ... hmmm... so hard to put it in a non-offensive term. Let's say ignorant and/or opportunistic.

Converting to conventional is an objective downgrade in quality. AHC is more complicated, but a superior system. If you're willing to get the bleed figured out and do some basic and infrequent upkeep, AHC is quite reliable.

Thank you. So I definitely introduced air into the system. The reservoir is full, and the truck is completely bottomed out. So when I turn it on it doesn't raise at all.

So it is possible to bleed air from the system if the truck does not raise at all on its own?

What is the best process to get the air out if it does not raise? Locate the output line from the bump block and crack it open then close it and turn the car on and try again?

Apologies for low level questions, the system is new to me and trying to understand.

 

[suprarx7nut]

Thank you. So I definitely introduced air into the system. The reservoir is full, and the truck is completely bottomed out. So when I turn it on it doesn't raise at all.

So it is possible to bleed air from the system if the truck does not raise at all on its own?

What is the best process to get the air out if it does not raise? Locate the output line from the bump block and crack it open then close it and turn the car on and try again?

Apologies for low level questions, the system is new to me and trying to understand.

Yes, albeit annoyingly. Crack the line coming off the pump block. Be sure to only use a line wrench. Just crack it a tiny bit until fluid comes out, then tighten again and fire up the car and see if the pump will run.

The AHC system is similar to an ABS boosted brake system. Bleeding is critical and when you get air in, it can be a pain to get it out.

 

[AClarko]

Yes, albeit annoyingly. Crack the line coming off the pump block. Be sure to only use a line wrench. Just crack it a tiny bit until fluid comes out, then tighten again and fire up the car and see if the pump will run.

The AHC system is similar to an ABS boosted brake system. Bleeding is critical and when you get air in, it can be a pain to get it out.

Yes, albeit annoyingly. Crack the line coming off the pump block. Be sure to only use a line wrench. Just crack it a tiny bit until fluid comes out, then tighten again and fire up the car and see if the pump will run.

The AHC system is similar to an ABS boosted brake system. Bleeding is critical and when you get air in, it can be a pain to get it out.

I cracked until just a dribble came out, tighten it back up, fired up the cruiser and no action. Pump still just whines with the full reservoir.

Should I keep repeating that? Or should I try to bleed some of the actuators?

I only touched driver side front and accumulator before I wrecked this system. The back seems to be sitting a few itches higher, not sure if any of that matters.

Thanks.

 

[suprarx7nut]

I cracked until just a dribble came out, tighten it back up, fired up the cruiser and no action. Pump still just whines with the full reservoir.

Should I keep repeating that? Or should I try to bleed some of the actuators?

I only touched driver side front and accumulator before I wrecked this system. The back seems to be sitting a few itches higher, not sure if any of that matters.

Thanks.

View attachment 2817021

If the pump is running, you're making progress. Ensure fluid is over max full. I would try bleeding the corners. Cracking the pipe off the pump block is useful when the pump won't run. If the pump runs, you should be moving fluid throughout the system, albeit just a little at a time. The pump noise is a good indicator of when it's moving entrained gas vs pure liquid. Listen for how it sounds and for how long it runs before flashing the AHC off light.

Of course, an underlying theme here is that techstream helps with all this. Possible to navigate through it without, but very helpful if you have it.

Let us know how bleeding a corner (or all of them) goes. Moving fluid is the name of the game now.

 

[AClarko]

If the pump is running, you're making progress. Ensure fluid is over max full. I would try bleeding the corners. Cracking the pipe off the pump block is useful when the pump won't run. If the pump runs, you should be moving fluid throughout the system, albeit just a little at a time. The pump noise is a good indicator of when it's moving entrained gas vs pure liquid. Listen for how it sounds and for how long it runs before flashing the AHC off light.

Of course, an underlying theme here is that techstream helps with all this. Possible to navigate through it without, but very helpful if you have it.

Let us know how bleeding a corner (or all of them) goes. Moving fluid is the name of the game now.

I started with the rear passenger corner. A good amount of nasty black fluid drained and the rear end lowered. I closed the valve then turned the car on to pressurize. Pump whined for about 30 seconds, didn’t raise and fluid in reservoir remind the same.

I moved to passenger front, a very small amount came out like just a couple inches through the tube. Turned the car on to pressurize this time the pump whined for about a second then stopped. l then cracked the pipe off the pump let a tad out and tightened it back up.

Same thing. Ran for about a second. I tried turning the car off and on again this time clicking the “Hi” setting, the pump ran a little longer maybe 10 seconds.

I moved to driver side rear, cracked the valve and nothing came out. Turn the car on about a second whine then turned it off and tried the front driver side. Nothing came out.

Looks like there is nothing to drain anymore. The accumulator had nothing and the corners are empty. I can get the pump to run for a few seconds if I click the hi setting but it doesn’t pump anything

Not sure what else to try but I appreciate the help thus far though.

 

[suprarx7nut]

I started with the rear passenger corner. A good amount of nasty black fluid drained and the rear end lowered. I closed the valve then turned the car on to pressurize. Pump whined for about 30 seconds, didn’t raise and fluid in reservoir remind the same.

I moved to passenger front, a very small amount came out like just a couple inches through the tube. Turned the car on to pressurize this time the pump whined for about a second then stopped. l then cracked the pipe off the pump let a tad out and tightened it back up.

Same thing. Ran for about a second. I tried turning the car off and on again this time clicking the “Hi” setting, the pump ran a little longer maybe 10 seconds.

I moved to driver side rear, cracked the valve and nothing came out. Turn the car on about a second whine then turned it off and tried the front driver side. Nothing came out.

Looks like there is nothing to drain anymore. The accumulator had nothing and the corners are empty. I can get the pump to run for a few seconds if I click the hi setting but it doesn’t pump anything

Not sure what else to try but I appreciate the help thus far though.

Thanks for the update.

Sounds like the pump is having a hard time getting a prime. Does it seem as though the pipe off the pump block is full of fluid?

 

[AClarko]

Thanks for the update.

Sounds like the pump is having a hard time getting a prime. Does it seem as though the pipe off the pump block is full of fluid?

No, thank you for the help.

When I crack it open fluid drips out every time. Should I open the pipe off the pump even more? How can I prime it?

 

[suprarx7nut]

No, thank you for the help.

When I crack it open fluid drips out every time. Should I open the pipe off the pump even more? How can I prime it?

Ok, try the following. These are the steps provided by the FSM.

1. Check fluid level.
2. Manually power pump to force it to run (optional for you since you know the pump motor runs)
3. Bleed air with the SST (a paperclip or wire or something conductive). This is a way to manually override the built in safety modes and get that pump primed and moving fluid even when air is present.

 

[AClarko]

Ok, try the following. These are the steps provided by the FSM.

1. Check fluid level.
2. Manually power pump to force it to run (optional for you since you know the pump motor runs)
3. Bleed air with the SST (a paperclip or wire or something conductive). This is a way to manually override the built in safety modes and get that pump primed and moving fluid even when air is present.

Oh man..how am I screwing this up. Am I in the wrong port here? It’s by the brake pedal. I have removed this metal paper clip multiple times. In 4 & 12 just like it says and pressing the down button 5 or more times in 5 seconds after turning it on, but it won’t go into the mode and rapidly flash the OFF light. It looks like slot 12 doesn’t have anything in the pin that it’s in?

 

[suprarx7nut]

Oh man..how am I screwing this up. Am I in the wrong port here? It’s by the brake pedal. I have removed this metal paper clip multiple times. In 4 & 12 just like it says and pressing the down button 5 or more times in 5 seconds after turning it on, but it won’t go into the mode and rapidly flash the OFF light. It looks like slot 12 doesn’t have anything in the pin that it’s in?

View attachment 2817232

There's definitely a chance the 06 manual I showed is different than earlier years. Hang on, let me do a little digging...

 

[suprarx7nut]

Ok, so Thanks Toyota/Lexus for changing up the DLC3 pins and Diag block (engine bay) over the years. Here's a couple options:

From PADDO:

Or if that yields no luck, try the Ts and E1 pins in the diag block in the engine bay.

I'm anxious to hear how this goes. This is a great example of info that's just not well defined and unless you have the FSM in hand, it's a bit of guesswork. If you can confirm which works for you, I'll document it on my site for others to reference in the future.

 

[AClarko]

Ok, so Thanks Toyota/Lexus for changing up the DLC3 pins and Diag block (engine bay) over the years. Here's a couple options:

From PADDO:

View attachment 2817244

Or if that yields no luck, try the Ts and E1 pins in the diag block in the engine bay.
View attachment 2817250

I'm anxious to hear how this goes. This is a great example of info that's just not well defined and unless you have the FSM in hand, it's a bit of guesswork. If you can confirm which works for you, I'll document it on my site for others to reference in the future.

I had to use the diag box in the engine bay.

As soon as I start it up the ABS, VSC, and OFF light are flashing.

Pressing down 5 times, switching to comfort and then holding up for 10 didn’t do anything though.

Tried a handful of times. I just don’t understand why it won’t engage!

 

[AClarko]

I had to use the diag box in the engine bay.

As soon as I start it up the ABS, VSC, and OFF light are flashing.

Pressing down 5 times, switching to comfort and then holding up for 10 didn’t do anything though.

Tried a handful of times. I just don’t understand why it won’t engage!

I take that back, when I press up I can hear the pump slightly and the interior lights dim just a tad, but even if I hold it 10 secs or more the car doesn’t raise. Bummer.

 

[suprarx7nut]

I take that back, when I press up I can hear the pump slightly and the interior lights dim just a tad, but even if I hold it 10 secs or more the car doesn’t raise. Bummer.

It's ok if it doesn't raise. That's not necessarily the goal. The goal is to move fluid (and the air causing our trouble here).

How long did the pump run? Have you tried bleeding a front corner since executing this trick?

 

[Jeremy9A]

Here is the procedure for performing "active test" on your 2000 LX470

Suprarx7nut is more familiar with this than I am so keep going with their advice