Check four wheel AHC system - Error message (1 Viewer)

[fcigoj]

Hi all,

SInce yesterday I am facing an issue with the AHC system on a 2009 LC200 diesel Euro version.
I had replaced the globes and the fluid on this car in December, and it has performed flawlessly ever since. It never had a problem beforehand either, but the globes were bust.
Yesterda, while driving on a straigh stretch of motorway at constant speed, I got a beep, the yellow warning sign appear on the cluster, and a message saying "check four wheel AHC system".
At the same time the up and down arrows on the AHC position indicator disappered.

The problem persisted until I parked the car, and my Scangauge could not detect any error codes.
This morning the car performed flawlessly, and I tried L, N and H positions without receiving any complaint.
Two hours later, again the same sequence as above appeared, and didn't change until I parked.
Most likely tomorrow it will be the same...but who knows ?

Has anyone experienced something similar ?
Grateful for any input

 

[radman]

have you checked your AHC fluid? Are you familiar with how to do this using a flashlight?

 

[grinchy]

I have gotten a similar error, but I think there was an associated code. The root cause was the connector to the AHC pump was loose. The connector is inside the frame rail, at right rear. Maybe drop the tire, and plug and unplug this?

 

[fcigoj]

have you checked your AHC fluid? Are you familiar with how to do this using a flashlight?

I have checked, and the level is as I left it, at max in N position

 

[fcigoj]

I have gotten a similar error, but I think there was an associated code. The root cause was the connector to the AHC pump was loose. The connector is inside the frame rail, at right rear. Maybe drop the tire, and plug and unplug this?

Thanks, I will try

 

[fcigoj]

Update: a Toyota dealer in Germany looked at the problem and diagnosed a failure of a control valve and the ECU, for a total cost of 5500 EUR.

The system has been on and off several times before becoming completely inactive, and I am not too sure of their conclusions.
Surely I would like a second opinion before forking out such money.
Any ideas ?

 

[TheComedian]

Phew… ok sounds bad. Would definitely check the thing with the connector since our Toyota dealers here are not that used with 200s to be honest. Brought them once my 200 to check if they could teach a new key after I didn’t managed to do it by myself via Techstream and they also where like „yeah must be the key ecu blablabla 3k+€… blabla“… figured it out by myself and found out it was a receiver unplugged.

Check out if you can reprogram the ECU for this by yourself and then get the parts via Partsouq. They arrive normally within a week here in Germany and sre pretty likely mostly 1/4 to 1/3 of the price the dealer asked here.

 

[grinchy]

Update: a Toyota dealer in Germany looked at the problem and diagnosed a failure of a control valve and the ECU, for a total cost of 5500 EUR.

The system has been on and off several times before becoming completely inactive, and I am not too sure of their conclusions.
Surely I would like a second opinion before forking out such money.
Any ideas ?

are you able to get the FSM (available in another thread on this forum)? That will give you the details on where the control valve is and how the system is configured.

If it really is the valve there has been at least one forum member that replaced it with a used part successfully.

 

[fcigoj]

are you able to get the FSM (available in another thread on this forum)? That will give you the details on where the control valve is and how the system is configured.

If it really is the valve there has been at least one forum member that replaced it with a used part successfully.

I think the valve is located near the pressurized reservoir fixed to the inner side of the frame rail, not a nice location to work but...
However, I don't understand their quotation...on Megazip both the valve and the ECU are less than 2000 $
Also, before replacing the ECU, wouldn't you replace the valve and see ?
I mean, all in all it seems that they have just followed the checklist and foreseen to replace all there is between the battery and the oil

 

[fcigoj]

are you able to get the FSM (available in another thread on this forum)? That will give you the details on where the control valve is and how the system is configured.

If it really is the valve there has been at least one forum member that replaced it with a used part successfully.

I have tried to make sense of a couple of things before touching anything, especially because where I am it is not easy.
If I remember well, I had read somewhere in another thread on the subject that you said something about the fact that when the ECU is dead there is no indication of the position, while my display shows a clear N inside the vehicle shape, although the arrows are obviouisly obscured as there is no control.
Do I remember correctly ?

 

[grinchy]

I have tried to make sense of a couple of things before touching anything, especially because where I am it is not easy.
If I remember well, I had read somewhere in another thread on the subject that you said something about the fact that when the ECU is dead there is no indication of the position, while my display shows a clear N inside the vehicle shape, although the arrows are obviouisly obscured as there is no control.
Do I remember correctly ?

I’ve never had a dead ecu. I had an unplugged wire to the pump. Dash showed Ahc error or something similar.

An unplugged ecu there is no Ahc section on the MID.

I suggest you get the fsm and read thru the troubleshooting section, that’s likely what the dealer did you can follow along at home and verify or find new root cause.