AHC system help!

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vsatking

vsatking

10 Year
Joined
Feb 3, 2015
Threads
8
Messages
479
Location
Madison, WI
I am on my 5th Land Cruiser/LX and today is the first day I have ever been to a Lexus dealer for service work.

Here is the sy.

I bought my LX570 6 months ago. A 2011 with 125k. It had perfeft dealer service on schedule. Previous owner had the dealer replace the front shocks and AHC pump at 105k.

Last month my Check AHC Suspension Service Now (or something like that) came on. The warning would come on when it gets cold. I ordered 2.5 qts of fluid to do a flush. I did a flush last weekend. When I removed the fill cover in the rear wheel well I found there to be almost no fluid in the reservoir. I did a drain and fill per many videos. It went well. I did not see any air in the lines. I was expecting to see some based on how low the fluid was.

Two days later when I parked my LX outside in cold Temps the error came back. I could get the light to go off if I started and stopped the LX a few times. I checked the AHC fluid level again 2 days ago. The fluid level was quite low .

I had rushed 2 containers of the 2.5l of the AHC containers to my house.

My wife urged me to call the dealer and just take it in. With Christmas, a full kitchen to install and promotion at work I just have so little time and a bit more money. The Lexus dealer had immediate opening for this morning.

I wrote a full page letter to the service dept with all that I did and when the error comes up.

The initial service writer seemed to know what I was talking about and could see that not a single service was missed.

I am very worried to have someone work on my vehicle other then me. Let's hope it goes well. The dealer was all about hitting me a loaner, coffee and a free cookie.

I am expecting to pay a premium (I did get a cookie). I truly hope they get to the bottom of the issue.
 
Hopefully you don't get in a situation like @eatSleepWoof did a couple year back.

What's obvious is you have a leak in a line somewhere, 3 liters of fluid doesn't just go missing.
 
Lock your glove box and keep your key blade with you to prevent them destroying your recirculate flap!
 
I just had a leaky line (rusted out, car was originally an East coast) replaced by the dealer here in Colorado Springs. They also did a flush, system is working perfectly. Based on what I have read CoS seems to be one of the few dealers who know what they doing on AHC. My regular shop, which only works on Japanese cars won't touch AHC.
 
slipkid13 said:
I just had a leaky line (rusted out, car was originally an East coast) replaced by the dealer here in Colorado Springs. They also did a flush, system is working perfectly. Based on what I have read CoS seems to be one of the few dealers who know what they doing on AHC. My regular shop, which only works on Japanese cars won't touch AHC.

This is my wory! You would have to know the system to trace down a leak. I would bet this dealer does not see many LX and AHC type of work. I was expecting them to find a corroded line.
Click to expand...
 
Update - dealer called me today. They could not find a leak and the Check AHC system light is not coming on. The service person said they left the LX inside over the weekend. I mentioned my comments in the letter and what I verbally told the service person....it only happens in the cold. The service person said they would keep it for another day and park it out side in the cold to see if they can reproduce the check message.
 
Did you have them pull the DTC that is triggering the check AHC?
 
The dealer parked my LX outside overnight. The Check AHC code did come on. They pulled the DTC and the code referenced (they did not give me the code) low oil pressure from pump. They recommend the pump be replaced at a cost of $4100. I talked to the service advisor and asked if they had seen a pump go bad in 25k miles. The last pump was replaced 25k miles ago.

I am going to do some digging into this low oil pressure issue in the forums. I don't know the ins and outs of the AHC and have a lot to learn.

Any advice would be greatly appreciated!!
 
vsatking said:
The dealer parked my LX outside overnight. The Check AHC code did come on. They pulled the DTC and the code referenced (they did not give me the code) low oil pressure from pump. They recommend the pump be replaced at a cost of $4100. I talked to the service advisor and asked if they had seen a pump go bad in 25k miles. The last pump was replaced 25k miles ago.

I am going to do some digging into this low oil pressure issue in the forums. I don't know the ins and outs of the AHC and have a lot to learn.

Any advice would be greatly appreciated!!
Click to expand...
There is no reason for the pump to go bad in 25k miles. Many people on the 100-series LX run those pumps well over 200k miles without issues, and the 200-series AHC is more robust in every way.

The key to keep in mind is that the AHC pump is NOT self-priming. That means if the pump is not primed, or otherwise runs dry of fluid, it WILL burn out. (My local dealer learned that the hard way.)
 
That might be the problem. I saw the fluid very low for some reason. Dealer could not find a leak.

I am looking at other options now. Wonder if there is a check valve issue with air trapped in the system.

Any way to test the pump is burned out. Would cold 25 deg affect a burned out pump more then moderate cold at 32deg?
 
I've no idea whether temperature would affect the pump. I suppose it could affect AHC fluid viscosity, which would affect the amount of "effort" the pump has to put in, and if the pump is weak for whatever reason, that could result in the problems you're seeing.

When my pump was burned out, the LX was stuck in "low" and could not raise its height. It also showed a clear error on the dash, something along the lines of "check AHC system".

The dealer can likely test the pump. If they don't want to remove it and manually power it (while running fluid through the system), they can at least test it with Techstream; I'm almost certain there's a built-in procedure for that.

I would top-off the AHC tank with new fluid, take the truck home, and do a damn thorough job of ensuring there's no leak. Only after that would I consider replacing the AHC pump.

Have they looked at other AHC components? The globes/accumulators are an eventual maintenance/replacement item, perhaps there's an issue somewhere with those components. This video may be helpful:
 
Another question...

The issue is intermittent depending on cold. Would that rule out lack of priming in the pump?
 
Thank you eatSleapWoof! I am right there with you. If the pump lost priming then the system should not have raised to begin with when I added fluid. I think there is something else going on here. I told the dealer I am going to pick it up and do some forum searching to verify a pump can go toasting after 25k miles.
 
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