AHC Issue - Not working after leak repair

[clouter]

Good day everyone !

I'm having an issue with my 2010 LX570's AHC suspension.
Truck has 170 000 canadian kilometers (106k miles)

Everything was working fine until I started having an oil leak from one of the AHC suspension hoses three weeks ago (tiny drips).

Circled in blue is the faulty hose.

After replacing the hose, my tech at work, not knowing the exact procedure to bleed the AHC system, unscrew the bleeder from the Suspension Control Pump Accumulator Assembly (a lot of fluid came out at high pressure).

Then I explained to him the bleeding procedure (that I found here reading) which we did (put truck in L, fill tank, unscrew one corner at a time starting from front driver, start truck and adjust level). Now there is no more air at any of the 4 bleeder valves and new and clean fluid comes out.

My problem is :
When I start the truck, the dash indicates N position for a couple seconds (even though the truck is physically completely dropped down) and we hear the pump run. Then the pump stops and I get a CHECK AHC SUSPENSION SYSTEM error and the dash indicates L for low. If I want to raise the truck nothing happens.
If I turn off the truck and back on again it will again indicate N and pump will run. If I quickly try to raise it, the arrows will light up like it's trying to lift the truck but it doesn't lift and after about 10 seconds I again get the CHECK AHC SUSPENSION SYSTEM and dash indicates L.

Now the Suspension Control Pump Accumulator Assembly seems empty because if we open the bleeder nothing comes out (whether the truck is on, off, on and AHC pump running, on and AHC pump running and trying to lift the truck, nothing)...

I tried searching and someone posted in the 100 series section something about lifting the front wheels off the ground to relieve pressure to allow to bleed the Control Pump Accumulator Assembly. We tried doing that and playing with the bleeder and still nothing comes out.

I need help !!!!
In the meantime my tech and I are trying to get our hands on a FSM

 

[lx200inAR]

The truck will not try to fill the accumulator until after a successful L->N or N->H. So it makes sense that its not building any pressure for you now. I'd leave the accumulator alone for now, since you know the pump is still working.

My advice is to do the restart thing a few times. First I would use the down arrow to get the AHC ECU to agree that the truck is in L when it should be in L. Then, I'd restart it and push the up button once to get it to attempt to lift (push up button right after startup before the AHC ECU does it's full health check). Once it stops trying to lift (flashing up arrow on MFD stops) and you get the check AHC light, stop the truck and repeat. You may have to do this 3-4 times before the truck will start to lift. Once you get it to N, don't turn the truck off immediately because then the pump will start filling the accumulator.

If that doesn't work, you will probably want to start working on getting your hands on a Techstream setup.

edit: Also make sure you have plenty of fluid in the reservoir, and I hope you inspected the fluid you put in. There has been a rash of bad fluid coming strait from dealers that has been fouling the AHC pump filters and starving the pumps.

One of a couple threads with similar issues of bad fluid.

HELP! AHC Pump Issue After Reservoir Drain/Refill

forum.ih8mud.com

 

[clouter]

So I tried the restart thing about 10 times and to no avail, I am not able to get even a slight bit of lift, and when I start the car it will randomly tell me I'm either in L or N.
Sill getting the AHC error after ten seconds.

 

[lx200inAR]

Hope you didn't get the bad fluid. The people who did have reported pretty much the same symptoms. See that previous thread I linked for a description of the bad fluid.
The people who have used the bad fluid used techstream to monitor pump pressures and found that the pressure won't build up past about 3MPa (should see it go between 7-8 MPa when going from L->N typically).

It's possible you might just be air locked and need to get the pump primed. You might try running the pump with the line that you replaced cracked to get fluid flowing through. But I'd probably inspect the fluid first at this point, since we know of at least 3 or 4 instances of people getting bad fluid (and possibly more as there were more situations where pumps were replaced leading up to the discovery that the fluid was the problem.

Can you hear the pump "ramping up" as it pumps before it shuts off?

 

[clouter]

Hope you didn't get the bad fluid. The people who did have reported pretty much the same symptoms. See that previous thread I linked for a description of the bad fluid.
The people who have used the bad fluid used techstream to monitor pump pressures and found that the pressure won't build up past about 3MPa (should see it go between 7-8 MPa when going from L->N typically).

It's possible you might just be air locked and need to get the pump primed. You might try running the pump with the line that you replaced cracked to get fluid flowing through. But I'd probably inspect the fluid first at this point, since we know of at least 3 or 4 instances of people getting bad fluid (and possibly more as there were more situations where pumps were replaced leading up to the discovery that the fluid was the problem.

Can you hear the pump "ramping up" as it pumps before it shuts off?

Thanks for the help !

I too hope we did not get bad fluid. I guess I'll have to check for a techstream setup...
And no I cannot hear the pump ramp up before it shuts off, it's a constant high pitch sound.

 

[grinchy]

My guess is the pump has lost prime. Some members have had success running it backwards to reestablish the prime.

lots of progress in this area the last couple weeks.

 

[clouter]

Thanks for your replies ! I read some more AHC threads and will try this tomorrow :
- Run pump backwards
- Inspect fluid

I will keep you posted

 

[BigLexusMN]

I just did the AHC fluid change myself with zero issues and many ups/downs of the suspension in mixed driving. So, I'd syphon out some fluid from the reservoir and inspect it for white globes of goo, first. Start by removing the little filter in the filler next of the reservoir fill tube and inspect it.

You could also remove your AHC pump and inspect the little filters (not an expert on this, read the threads) to see if they are clogged and therefor, your pump is not building enough pressure like other members have mentioned.

 

[Whiskeyding]

what happened how did you fix it? I'm having exactly the same issue! Please pm me Your solution!