AHC won’t lift (1 Viewer)

[NielsC]

My friends 200 was suddenly stuck in low position, it wouldn’t raise and gave the check AHC system on the dashboard.
First thing I checked was the heigth sensor.
The adjustable rear left arm was a bit loose and could slide in the slot, so i tightend it again at were it visibly was before.
I disconnected the battery, but stil the same after reconnecting.
Also no oil leaks were found.
When it was in LOW the oil in the reservoir looked like it was below minimum.

So i read the codes with techstream and we would have a code for the rear RIGHT heigt sensor (the LEFT one was loose) and “C1763 abnormal oil pressure”.
We deleted the codes, and as soon as we try to lift the car with the up button the code C1763 comes up immediatly. We hear the pump run for a second but then stops as the “Check AHC system” comes on.

We then tried to lift the car with the utility functions, but this made it drop on to the bumpstops instead of lifting it.
Now we are somewhat unable to see the oil level in the reservoir, makes me think it is completly full because of the dropped suspension.

We are now scratching our heads a bit as we have no FSM of the AHC system to help diagnose it.
Any of you have had something similar like this or can point us in the right direction? Any help is greatly appreciated!

 

[Sandroad]

I'm ignorant of the AHC, but it might be worth checking on ideas in this thread.

LX570 AHC “Basics” - Added as sticky thread for AHC Issues

Point of this thread is to serve as a repository for 200-series AHC info, including LX570 and LC equipped with AHC (in select global markets). Let’s begin with a theory. The 200-series LC (without AHC) and the LX570 (or LC with AHC) are like New York & LA. LC “purists” are like New Yorkers...

forum.ih8mud.com

 

[radman]

You’ll need to work on getting a flashlight shooting directly into the reservoir to see the level. Try coming in from the side where the spare is.

How many miles?
Any history of ach fluid being changed?

 

[NielsC]

You’ll need to work on getting a flashlight shooting directly into the reservoir to see the level. Try coming in from the side where the spare is.

How many miles?
Any history of ach fluid being changed?

This is what I did with the flashlight to see it
No history of the fluid being replaced
It has 125,000 miles on it

 

[radman]

First step:
You need to figure out of the reservoir is completely full, or completely empty.

 

[NielsC]

The oil is above the maximum.
I disconnected the big plug at the frame at the rear quarter wich goes to the AHC pump, I’ve put 12V directly on the pump, no noise, nothing!
I’ve checked the supply after clearing the DTC code and after starting the engine, for a second I measure 12V untill the “check AHC” message comes on. So I think it is save to say the AHC pump is toast?

 

[radman]

12v to the pump should definitely work. Some have swapped the pos/neg to run the pump in reverse...
what kind of battery did you use to get 12v to the pump?

 

[NYC570]

Just in case it turns out to be the pump, I believe someone is selling a used one in the classifieds section.

 

[NielsC]

12v to the pump should definitely work. Some have swapped the pos/neg to run the pump in reverse...
what kind of battery did you use to get 12v to the pump?

Yeah, so it did nothing. I might try seeing what it does in reverse but I’d think nothing aswell.
I used a 12V supply from another car battery.

 

[radman]

Yeah, so it did nothing. I might try seeing what it does in reverse but I’d think nothing aswell.
I used a 12V supply from another car battery.

There shouldn't be any amp draw issues from another car battery, but I hate to ask... are you sure that battery is putting out over 12v?

 

[NielsC]

There shouldn't be any amp draw issues from another car battery, but I hate to ask... are you sure that battery is putting out over 12v?

Haha , yeah I’m sure. The 12V was from 2 jumper cables from a running car, I even checked for 12V to be 100% sure

 

[grinchy]

There have been some pump failures from clogging, but a straight up electrical failure is rare.
You’re probably at the pull the reservoir and pump for bench testing stage.

 

[NielsC]

There have been some pump failures from clogging, but a straight up electrical failure is rare.
You’re probably at the pull the reservoir and pump for bench testing stage.

Yeah it needs to be pulled out anyway, but I dont think there’s much bench testing left if it doesn’t run with power directly on the plug.