AHC Problems immediately after Dealer Flush (1 Viewer)

[DenverLX]

I have a 16' LX570 still under warranty and I took it to the dealer for the 60,000 mile service which includes a flush of AHC fluid. They were able to complete the job the same day and I returned to pick up my truck and a few miles from the dealer my car starts telling me "Check AHC 4-wheel control." I called the dealer and they said to bring it back so I did.

That was 3 days ago. They have no idea what the problem is and seem pretty unsure of the whole thing. I saw a thread by eatSleepWoof that seems like he went through the same problem. The dealer says they are currently thinking it is the pump... bad news is they said they are having trouble locating a pump...

Im a fishing guide and need to tow my boat and I'm sitting here driving a loaner Lexus NX. Im not very hopeful about anything getting fixed soon as the dealer seems stumped.

Any recommendations?

 

[04UZJ100]

If I were a betting man they put the wrong fluid in it or did not bleed the system correctly.

 

[TeCKis300]

It's not the pump, unless they've burned it out. Even with a new pump, it won't solve the issue. They need to get the fluid priming again as there's air stuck in the system.

Tell them to bleed the system and to make sure the AHC fluid reservoir is appropriately topped off and not to let it run dry again. Then bleed the "Suspension Control Pump Accumulator Assembly" at the top right of the system diagram. It located on the inner side of the frame around the middle of the chassis under a cover in the lower diagram.

Unfortunately this is a common mistake, and the repair manual doesn't do a good job of documenting how to resolve the issue.

 

[grinchy]

Agree with @TeCKis300 I do.

 

[DenverLX]

Thanks for the advice, I forwarded it on to the dealer. Hopefully this gets resolved but I have a feeling it’s going to take them a while

 

[DenverLX]

So the dealer got back to me today and they said:


“We've bled the system, and it doesn't look like evidence of air in the system. We provided our information with TAS showing that while running the pump in active testing mode, The system does not build any pressure confirming pump failure. TAS confirmed with us based off of everything else that we need to start with replacing the pump. We've got a pump on order just so that our name is on the list because as I mentioned before they are on a national backorder. It seems to be a common problem for these to go bad. We're still unaware of what happened and why the pump failed, so there are still some things that we have to sort out on our end.”

So basically I am screwed. I use my truck every single week for towing my raft trailer. I guide for fly fishing and literally need a truck. Instead I’m in a RX.... I’m at a complete loss on what to do.

 

[John Guedry]

Ask for a bigger loaner? A lx loaner or some truck w a hitch off their used lot.

 

[DenverLX]

I have made it very clear that I need a bigger car that can tow. Apparently the RX is all I can get. I don’t know what to do, I’m borrowing my brothers LC 100 this week, but I don’t know what I’ll do after that

 

[grinchy]

Sucks!
You may have to rent a uhaul van and charge it back to the dealer.

 

[Madtiger]

Hmmm…”…We've got a pump on order just so that our name is on the list because as I mentioned before they are on a national backorder. It seems to be a common problem for these to go bad.”

Is this true?! These pumps go bad so frequently?

 

[grinchy]

No. They make very few of them because they aren’t ever needed. <my opinion>

 

[DenverLX]

Well I follow these boards fairly close and I’ve never heard of it (except for one case that seemed suspicious).

 

[grinchy]

It only happens at dealers because they run them dry by bleeding without replenishing and they aren’t self priming.

 

[eatSleepWoof]

The pump didn’t just magically die. The dealer destroyed it by their incompetence.

Make 300% sure to warn those idiots that the pump is not self priming and HAS to be primed manually.

And I’m still betting there was/is air in the system.

 

[crow1969]

It's not the pump, unless they've burned it out. Even with a new pump, it won't solve the issue. They need to get the fluid priming again as there's air stuck in the system.

Tell them to bleed the system and to make sure the AHC fluid reservoir is appropriately topped off and not to let it run dry again. Then bleed the "Suspension Control Pump Accumulator Assembly" at the top right of the system diagram. It located on the inner side of the frame around the middle of the chassis under a cover in the lower diagram.

Unfortunately this is a common mistake, and the repair manual doesn't do a good job of documenting how to resolve the issue.

View attachment 2679656

View attachment 2679668

I just did a flush on my system following a couple guides that I saw on here. I seem to have pulled air into the system as well. Everything was working normally until the second time I drove the vehicle, about 3 minutes into the trip I threw the check AHC code. Stopped to examine what was going on and the pump was running noticeably loud. Based on what I've been reading thus far it sounds like I should bleed the control pump accumulator then the whole system starting at the drivers side front and working back to the passenger side rear valve. Is there anything else I should do in addition to that at this point? Should I bleed with the system in L? And how much fluid should I let out? I did some bleeding before driving after doing the job and didn't run into any air so I thought I was good. The guide I followed said to let out 500ml of fluid per corner and to add new fluid in. Shortly after I started having problems I found another forum saying you should absolutely not move more than 170ml out of the system at a time for risk of pulling air into the system. Needless to say my garage mechanic confidence has been dealt a serious blow. If the pump is already making spooky noises, am I going to have to manually prime it like some people have talked about? So many questions and seemingly a good bit of conflicting information. Sorry for the rapid fire questions, I'm just shook at the thought that I effed my poor truck up in a way that dealers even have trouble sorting out.

2010 LX570 -- 156,000

 

[grinchy]

Well that sucks. I don’t think it matters how much you take from each corner as long as you don’t run the reservoir dry at any time there won’t be air entering the system.

check the level of fluid right now in N and let us know where it is. Is the car going between heights?

 

[TeCKis300]

I just did a flush on my system following a couple guides that I saw on here. I seem to have pulled air into the system as well. Everything was working normally until the second time I drove the vehicle, about 3 minutes into the trip I threw the check AHC code. Stopped to examine what was going on and the pump was running noticeably loud. Based on what I've been reading thus far it sounds like I should bleed the control pump accumulator then the whole system starting at the drivers side front and working back to the passenger side rear valve. Is there anything else I should do in addition to that at this point? Should I bleed with the system in L? And how much fluid should I let out? I did some bleeding before driving after doing the job and didn't run into any air so I thought I was good. The guide I followed said to let out 500ml of fluid per corner and to add new fluid in. Shortly after I started having problems I found another forum saying you should absolutely not move more than 170ml out of the system at a time for risk of pulling air into the system. Needless to say my garage mechanic confidence has been dealt a serious blow. If the pump is already making spooky noises, am I going to have to manually prime it like some people have talked about? So many questions and seemingly a good bit of conflicting information. Sorry for the rapid fire questions, I'm just shook at the thought that I effed my poor truck up in a way that dealers even have trouble sorting out.

2010 LX570 -- 156,000

Hopefully this is your issue. It shouldn't be too hard to solve, and it's a matter of bleeding the right nipple at the control pump accumulator so the AHC pump is no longer dead-heading against high-pressure to prime again.

 

[crow1969]

Well that sucks. I don’t think it matters how much you take from each corner as long as you don’t run the reservoir dry at any time there won’t be air entering the system.

check the level of fluid right now in N and let us know where it is. Is the car going between heights?

AHC in N, fluid level is a little high. All throughout the flushing process it was fluctuating between height settings fine. And the first time I drove it after the change it went L to N, drove 15 minutes two ways then N to L back into the garage with no odd pump noise, trouble code or noticeable delay. It was the second time I took it out about an hour later that it threw the code, pump started sounding funny and cycling between setting would take forever. When starting the flush I put it in L and got my fluid pump hose way down in the reservoir which led to 1.9L of fluid being evacuated. I replaced with the same amount immediately after and before operating the system at all. Does that sound like anything that would have caused an issue? That would have been the only time the reservoir was totally empty, but the system wasn't run at all in that state.

Hopefully this is your issue. It shouldn't be too hard to solve, and it's a matter of bleeding the right nipple at the control pump accumulator so the AHC pump is no longer dead-heading against high-pressure to prime again.

View attachment 2683899

Thank you very much, I'll give this a shot tomorrow and report back!

 

[tacoduck]

I’m curious. Why not just suck the fluid out of the reservoir and swap with clean fluid? I know its a shortcut, but if it remove 90% of the old fluid, wouldn’t that be good?

I know this doesn’t help op, but I’m thinking of servicing mine at 75k.

OP, is Lexus going to cover the pump?

 

[grinchy]

I’m curious. Why not just suck the fluid out of the reservoir and swap with clean fluid? I know its a shortcut, but if it remove 90% of the old fluid, wouldn’t that be good?

I know this doesn’t help op, but I’m thinking of servicing mine at 75k.

OP, is Lexus going to cover the pump?

It’s not much more work to bleed thru to clean fluid and do it 100%.

the thing is, any maintenance could go wrong for any number of unusual reasons. Brake tranny power steering gear even oil changes. The only difference is AHC is a system that doesn’t have 100 years of common experience behind it, so knowing what to ‘do next’ and how to do it isn’t muscle memory.