LX570 AHC fluid change issue

[Kieranz]

Hi,
Symptom: I am changing out my AHC fluids for the 2nd time (hit 120k miles) on my '16 LX570 and have run into an issue where the pump continues to run, and the car will "sometimes partially raise" going from N to H - and the new fluid in the reservoir will barely go down. I haven't attempted to go to L since experiencing the issue - since I don't want my car to risk bottoming out the car and having it stuck there. After about a minute of the AHC motor running, the car's display will indicate AHC issue and will lock out AHC functions until I restart the car. Hoping to get a tip from someone here that can help reset (or bleed air out of ) the system without going to someone with Techstream. I also tried unplugging the battery for a few minutes, before trying again to have the pump run with minimal raise. The reservoir was never dry at any point - I made sure of that.

Prior to the fluid change: Car's suspension worked normally before the procedure. Never had issues going to H or L.

Procedure: I added about 1 qt of new fluid to the rear wheel reservoir before starting, making sure I never went empty at N. I then went and drained the accumulator for 10 seconds three times (about a pint of fluid out) and then restarted the car. The AHC motor would whine for a while. The pump is very slow to pull any of the new fluid into the accumulator. most of the time the level doesn't move downwards. The car won't go into high. I did move onto the DS front globe and did a drain. The car did raise the driver side front. Albeit it took a few times of trying (by cycling car on and off to clear the error).

Any ideas? Thanks in advance.

 

[nwfl4runner]

Did you bleed each corner, starting the car after each to raise to normal?

 

[Kieranz]

Did you bleed each corner, starting the car after each to raise to normal?

I only got so far to bleed accumulator and DS front. I started the car after each bleed. Had issues right away after the first accumulator bleed.

Never moved to other 3 corners.

 

[nwfl4runner]

Did you use metal fluid can or plastic?

 

[Kieranz]

Did you use metal fluid can or plastic?

2.5L metal cans of AHC fluid.

 

[nwfl4runner]

Give the other 3 corners a shot - try passenger rear, then driver rear, then passenger front. Forget going into high for now / you want to bleed each corner and have it return to high - see if that works

 

[lx200inAR]

If you drained the accumulator first, then you took away the systems best method of raising when you try to change heights. That probably explains why you are lifting very slowly. If you are hearing a higher pitched whine from the pump, like it's starved, I'd try pulling the fill plug on the reservoir. I've had issues before where it seemed like vacuum was keeping the pump from filling the globes.

I'm not sure how often the system will attempt to fill the accumulator. I'm pretty sure I've seen the ECU check for the amount of pressure stored, but I don't know if it will attempt to fill the accumulator any time other than after a lift from L to N or from N to H.

The normal process when you lift from L to N (or N to H) is the pump engages (to start lift and close the valve that allows fluid back to the reservoir) and then the system releases stored fluid from the accumulator to lift the truck. The pump continues to run to fine tune the heights. Once the truck has reached the new level, the height control valves close, and the accumulator valve remains open and the pump continues to fill the accumulator until it is ready (somewhere around 13mpa).

If the accumulator doesn't have stored fluid, then the pump has to complete the lift on its own. The ECU will use the pump to do this, but it can take quite a while. I've even found that the screen will say that the lift is complete and switch to N, even though the sensors have not reached their full height. The truck will continue to run the pump in cycles until you reach full height. In that state, I've found it can take a while for the truck to repressurize the accumulator. Until that happens, all your lifts will be very slow.

The moral of this story is that as long as you aren't getting the abnormal pressure alert, generally the system will work itself out in time. I think pulling the plug on the reservoir can help (only while parked), but, also I've found just driving the truck around for a while will give the truck time to adjust back to normal. I wouldn't go romping any dunes, but take a leisurely drive around the block. It's also much more comforting if you use Techstream or OBD Fusion to watch what the AHC ECU is doing rather than stressing over whether or not it's about to implode.

 

[chriscosta416]

To echo what others have said, bleed each corner, there is no need to bleed for a long time. Do quick bleeds on each corner, top off AHC fluid and start the car.

Do you have techstream at all?

 

[Kieranz]

So I brought the car to the Lexus dealer today to see if tech stream could help and I am limited in time to troubleshoot. They put into test mode and the pump isn't pulling any fluid. And the pump is whining. They drained all the globes, so the car is on the bump stops with no ability to raise it. Had a long conversation with the tech (who seems familiar with the system) and sympathetic to my cause.

The part is $3300 and labor $1200+ (3 hours to change the pump and 2 hours to bleed). Any thoughts here?

1) Do I drive back on the bump stops and hope the pump isn't shot and try to evacuate air on the system
2) or go to the parts cannon and bite the big bullet here? I may be able to get them to price match the part with Bell Lexus to ease the cost - if I go this very expensive route.

I am currently here at the dealership trying to figure out my next steps.

Here are the tech stream readings. Thanks everyone!

 

[Kieranz]

BTW, tech stream is reading C1763 - " abnormal oil pressure for pump motor"

 

[lx200inAR]

So I brought the car to the Lexus dealer today to see if tech stream could help and I am limited in time to troubleshoot. They put into test mode and the pump isn't pulling any fluid. And the pump is whining. The drained all the globes, so the car is on the bump stops with no ability to raise it. Had a long conversation with the tech (who seems familiar with the system) and sympathetic to my cause.

The part is $3300 and labor $1200+ (3 hours to change the pump and 2 hours to bleed). Any thoughts here?

1) Do I drive back on the bump stops and hope the pump isn't shot and try to evacuate air on the system
2) or go to the parts cannon and bite the big bullet here? I may be able to get them to price match the part with Bell Lexus to ease the cost - if I go this very expensive route.

I am currently here at the dealership trying to figure out my next steps.

Here are the tech stream readings. Thanks everyone!

View attachment 3637932

View attachment 3637933

View attachment 3637934

I’d be very surprised if your pump is broken. Did you try opening the fill?

A pump can be ordered from over seas for closer to 1k. I wouldn’t pay dealer prices unless I was real desperate.

 

[Kieranz]

I’d be very surprised if your pump is broken. Did you try opening the fill?

A pump can be ordered from over seas for closer to 1k. I wouldn’t pay dealer prices unless I was real desperate.

I didn't try anymore since I originally posted. Let me see if the car is still on the stand in the back. He seems pretty cool. He may be willing to activate the test mode with the fill tube open.

 

[chriscosta416]

Part of the troubleshooting is to actuate the valves and do the active tests. See if that will resolve the issue.

 

[Kieranz]

Part of the troubleshooting is to actuate the valves and do the active tests. See if that will resolve the issue.

I think they did that. If I leave the dealer and take this back for further analysis, would you guys drive on the bump stops? Car is a low rider right now.

 

[chriscosta416]

I think they did that. If I leave the dealer and take this back for further analysis, would you guys drive on the bump stops? Car is a low rider right now.

You could but it will ride very rough. Do you have AAA to flat bed it to your house?

Do you have techstream at home?

 

[Kieranz]

You could but it will ride very rough. Do you have AAA to flat bed it to your house?

Do you have techstream at home?

lx200inAR - We just chatted with the master tech and he already tried with active test mode with the fill port open. No bueno. He also tried to add more fluid, but the reservoir is completely full now, since the car is on low, and I was above the max line when in normal mode.​

chriscosta416 - I don't have tech stream at home. But was planning to buy the Foxwell NT510 tool today, which has AHC visibility.​

Larry Miller Lexus parts manager unfortunately doesn't seem to want to price match Longo 48910-60033 ($1k cheaper) on the part - even though they have it in stock (sigh). The services dept was hoping they would. So I have a decision on whether to try to do this myself with Techstream at home, order the part online and either have the lexus dealer here do it or an independent install the new pump, or do an AHC delete.

 

[hurricane11]

I know when I did mine, I had a similar experience. It felt like the pump just kept running FOREVER before the vehicle would raise. I was worried I was going to hurt the pump, but it didn't seem to - I just watched to make sure it always had fluid in it and eventually it finally came back to full height. You have to get all the air out.

 

[Kieranz]

I know when I did mine, I had a similar experience. It felt like the pump just kept running FOREVER before the vehicle would raise. I was worried I was going to hurt the pump, but it didn't seem to - I just watched to make sure it always had fluid in it and eventually it finally came back to full height.

If I take it home and I try again not sure what options I have left. Car is currently on low on all bump stops. Reservoir is completely full with new AHC fluid. And presumably the globes are pretty empty with fluid. The tech running the active test mode hasn't done anything. Not sure if jacking a corner of the car up at home and letting it down will push any more fluid out.

 

[32cls6speedmt]

TOYOTA Genuine Land Cruiser 200 Lexus LX570 AHC Height Control Pump Motor | JDM Planet

jdm-planet.com

Just in case you want to order a new pump.

 

[lx200inAR]

Is it pumping at all when they turn it on? Or is it immediately going to the abnormal pressure? when mine was “being slow” it would generally only pump to about 2-3mpa then eventually give up. But persistence got It working again.