Still dizzy about AHC (1 Viewer)

[Manuel4x4]

Hi guys, how are you? Manuel from Chile

I'm struggling a bit with my 2011 Land Cruiser with AHC suspension, 120k miles on it. Years ago I had an LX with zero issues about the suspension, but this car is giving me headaches.

I know that there are a lot of Ahc posts, but sometimes they are too technicals and a bit hard for me to understand.

I haven't replaced anything yet (except the fluid), since I don´t know from where to start.

Some context:
- The rear suspension feels harsh and bumpy, especially on fast small bumps. On the road it felt good.

- Sometimes I feel the rear sagging down, with no suspension at all. Not only a feeling, I have seen it bottomed out.

- H and L are working, but not as they should. Sometimes it keeps blinking "L" when I bottom it from N and sometimes struggles to go up or down. I remember that the LX bottomed pretty fast, going rear first and then front, probably in 2 seconds. In this case, it's bottoming wheel by wheel, taking forever, and I have to drive a bit to complete the process.

- I already changed the fluid, with no changes at all.

- I lift it with the sensors, but I feel that every wheel is at a different height, specially the rear that is always lower than the front (when is not bottomed out obviously).

- Sometimes driving offroad, I had raised it to the top and when automatically adjusted it to N, the lower suspension stays down to the bottom, without any pressure at all. I had to reach something about 80 mph to get automatically set up again, very frustrating.

My question is, are there some quick checks to diagnose which part I have to replace? There are no parts for this car in my country and the importation fees are very high, so I want to be as sure as possible about what to change.

If someone had the sames issues, I'll be very happy if you could share some info and how did you fixed it.

Thanks guys!!

 

[bloc]

You really need to find someone with Toyota software to hook up to the vehicle and scan for codes. These systems are quite complex and computer diagnostics are critical to quickly finding the cause of problems.

 

[TeCKis300]

Hi guys, how are you? Manuel from Chile

I'm struggling a bit with my 2011 Land Cruiser with AHC suspension, 120k miles on it. Years ago I had an LX with zero issues about the suspension, but this car is giving me headaches.

I know that there are a lot of Ahc posts, but sometimes they are too technicals and a bit hard for me to understand.

I haven't replaced anything yet (except the fluid), since I don´t know from where to start.

Some context:
- The rear suspension feels harsh and bumpy, especially on fast small bumps. On the road it felt good.

- Sometimes I feel the rear sagging down, with no suspension at all. Not only a feeling, I have seen it bottomed out.

- H and L are working, but not as they should. Sometimes it keeps blinking "L" when I bottom it from N and sometimes struggles to go up or down. I remember that the LX bottomed pretty fast, going rear first and then front, probably in 2 seconds. In this case, it's bottoming wheel by wheel, taking forever, and I have to drive a bit to complete the process.

- I already changed the fluid, with no changes at all.

- I lift it with the sensors, but I feel that every wheel is at a different height, specially the rear that is always lower than the front (when is not bottomed out obviously).

- Sometimes driving offroad, I had raised it to the top and when automatically adjusted it to N, the lower suspension stays down to the bottom, without any pressure at all. I had to reach something about 80 mph to get automatically set up again, very frustrating.

My question is, are there some quick checks to diagnose which part I have to replace? There are no parts for this car in my country and the importation fees are very high, so I want to be as sure as possible about what to change.

If someone had the sames issues, I'll be very happy if you could share some info and how did you fixed it.

Thanks guys!!

From the symptoms, I think you've got a couple problems
- Sensor height adjustments out of wack, and as you said, every wheel is at a different height. Need to re-baseline the sensor heights. You can do trial and error by manually adjusting at the sensor brackets, but really need techstream to see what's going on. I wonder if you inadvertently raised the front sensors height but decreased the rear sensors which is easy to do as the sensor brackets need to be adjusted in opposite ways. Perhaps you can return the sensor bracket adjustment back to factory from the witness marks?
- The core issue sounds like you need new accumulators. They have ruptured or are bottoming out because of low nitrogen pressure. Sensor lifting on bad accumulators only exacerbates the problem. I'm not sure about Chile, but we can order OEM accumulators on Ebay direct from Japan for cheap.

 

[AnyMal]

Buenas Dias

The value that sensors send to ECU have bounds (limits) of discrepancy between each other in multiple ways. (Left / right, front / rear etc.) I don’t know what they are but they are frustrating and pretty small limits. If these are off, all sorts of problems can arise.

Right now all of your problems sound like exactly linked to this issue and generally sensor position (or values).

1) not raising or lowering
2) uneven heights
3) single strut alternating lifts / drop adjustments

Now your other issue of rear axle if I understood, not lifting at all after being off road could be a mechanical fault or a lockout or sensor is bad. But if it were a leak or mechanical fault your dash would be lit up.

 

[AnyMal]

Oh and check your battery voltage dog

 

[Manuel4x4]

From the symptoms, I think you've got a couple problems
- Sensor height adjustments out of wack, and as you said, every wheel is at a different height. Need to re-baseline the sensor heights. You can do trial and error by manually adjusting at the sensor brackets, but really need techstream to see what's going on. I wonder if you inadvertently raised the front sensors height but decreased the rear sensors which is easy to do as the sensor brackets need to be adjusted in opposite ways. Perhaps you can return the sensor bracket adjustment back to factory from the witness marks?
- The core issue sounds like you need new accumulators. They have ruptured or are bottoming out because of low nitrogen pressure. Sensor lifting on bad accumulators only exacerbates the problem. I'm not sure about Chile, but we can order OEM accumulators on Ebay direct from Japan for cheap.

Thanks for the answer. Look, I downloaded Techstream but don´t know yet how to read it properly. These are screenshots of the AHC data. Sensors are both at the highest (I know that rear are opposite, the thing that I dont understand yet is why the RR sensor is shorter than the RL)

On Neutral and in a flat surface, these are the numbers... pretty crazy I guess

Then, I press Low but the light start blinking :

Neutral Again (also blinking):

Finally High (no blinking):

 

[Manuel4x4]

Buenas Dias

The value that sensors send to ECU have bounds (limits) of discrepancy between each other in multiple ways. (Left / right, front / rear etc.) I don’t know what they are but they are frustrating and pretty small limits. If these are off, all sorts of problems can arise.

Right now all of your problems sound like exactly linked to this issue and generally sensor position (or values).

1) not raising or lowering
2) uneven heights
3) single strut alternating lifts / drop adjustments

Now your other issue of rear axle if I understood, not lifting at all after being off road could be a mechanical fault or a lockout or sensor is bad. But if it were a leak or mechanical fault your dash would be lit up.

Buenos días!
Yes, I think the problem is with the sensors. I may have explained myself wrong. The rear goes up and down when I press the buttons. The thing is that sometimes goes down to the bottom without notice. Sensors have reading in techstream, without any codes.
Its defenitly not working properly, but can´t figure it out why yet.
No always but sometimes if I lower it, the low button start blinking and I have to drive a bit to complete the descent

 

[Manuel4x4]

You really need to find someone with Toyota software to hook up to the vehicle and scan for codes. These systems are quite complex and computer diagnostics are critical to quickly finding the cause of problems.

I have Techstream, but just learning how to read it. I posted some live data of the AHC system

 

[CanadianRockyCruiser]

Your sensor heights from passenger side to driver side look pretty far off. Have you examined where the sensor bolts are tightened on each bracket? Might be worth a look! If they are loose or not adjusted similarly on each side of the vehicle, that might cause some of your issues. Take a look!

 

[AnyMal]

Man did you maybe spill some of that buen Café on the height switch?

Failure to lock modes is textbook sensor value mismatch and disparity.

Could even be dirty inside or worn. Take them off and check, it’s not super hard to reach.

Cleaning might fix it.

 

[Manuel4x4]

Man did you maybe spill some of that buen Café on the height switch?

Failure to lock modes is textbook sensor value mismatch and disparity.

Could even be dirty inside or worn. Take them off and check, it’s not super hard to reach.

Cleaning might fix it.

Thanks, I'll check that. I feel nothing switching the shock mode, sport or comfy, but in Techstream they are "working"

 

[Manuel4x4]

View attachment 3587785

Your sensor heights from passenger side to driver side look pretty far off. Have you examined where the sensor bolts are tightened on each bracket? Might be worth a look! If they are loose or not adjusted similarly on each side of the vehicle, that might cause some of your issues. Take a look!

Yeah, it´s so weird...both front shocks looks like they are at the same height. I suppose that if techstream is correct on those numbers, shock should be very uneven, dont they?

 

[AnyMal]

Yeah, it´s so weird...both front shocks looks like they are at the same height. I suppose that if techstream is correct on those numbers, shock should be very uneven, dont they?

You need to also show us the height offset data rifght below that.

 

[trudd]

No always but sometimes if I lower it, the low button start blinking and I have to drive a bit to complete the descent

This one aspect is normal in my experience for both raising and lowering. Sometimes - if you are pressing on the brakes - the arrow will disappear and the “L” or “N” will flash until you let go of the brakes. Pretty sure this can happen when in Park, Neutral, or Drive while the brakes are engaged.

 

[Manuel4x4]

You need to also show us the height offset data rifght below that.

 

[AnyMal]

View attachment 3588283

Rear right and left are supposed to be inverse because the ahc system is designed like that for some odd reason, maybe it’s calculating for a zero horizon idk who evern gives a flying y s*** at this point about AHC?

Anyways, there is like a 30+ mm discrepancy back there that’s not due to adjustment data. I would start with the rear sensor arms, check one isn’t slipped, set both by eye but don’t move them too much.

Like trudd was talking about AHC doesn’t work when you are on the brakes because it’s two hydraulic systems fighting each other. That is completely normal and intended behavior. Foot off brake for height changes.

 

[Manuel4x4]

Rear right and left are supposed to be inverse because the ahc system is designed like that for some odd reason, maybe it’s calculating for a zero horizon idk who evern gives a flying y s*** at this point about AHC?

Anyways, there is like a 30+ mm discrepancy back there that’s not due to adjustment data. I would start with the rear sensor arms, check one isn’t slipped, set both by eye but don’t move them too much.

Like trudd was talking about AHC doesn’t work when you are on the brakes because it’s two hydraulic systems fighting each other. That is completely normal and intended behavior. Foot off brake for height changes.

Thanks! yeah, I have always pressed up or down with my foot off the break, even in neutral gear keeps blinking.

Regarding the rear sensors I checked and the left one is longer than the right one, like if it had more travel. Is that correct?

 

[AnyMal]

Thanks! yeah, I have always pressed up or down with my foot off the break, even in neutral gear keeps blinking.

Regarding the rear sensors I checked and the left one is longer than the right one, like if it had more travel. Is that correct?

Sorry for the late reply, yes the rears are supposed to be like that. Nothing was loose back there?

 

[Manuel4x4]

Sorry for the late reply, yes the rears are supposed to be like that. Nothing was loose back there?

No worries, no nothing was lose, I want to fixed it but don´t know really where to start

 

[AnyMal]

No worries, no nothing was lose, I want to fixed it but don´t know really where to start

It’s ok, nobody does. Not even Lexus. lol

Tell us what you have done so far and hopefully someone can give you an idea of what may be.

My bet is still on bad or contaminated sensors. Have you pulled them off yet to inspect inside?