200 series AHC problems (1 Viewer)

[GvsB]

Hi all,

Been a member of Mud for a long time but not posted in a while, I'm based in UK and own a 2011 european spec 200 series, as you will know these are AHC equipped, as per the LX570's. Hopefully some of you will be able to help as these are pretty rare trucks in the UK and difficult to get anyone experienced with working on them.

Following a recent broken rear right hand height sensor linkage I am having issues getting the system functioning again, I have now replaced the sensor linkage, not the entire height sensor, I suspect it could be out of calibration but hopefully someone with more knowledge of AHC systems than me may have some suggestions?

I can get the AHC pump to run, but only after starting the car, and on the first press of a height selection. For example, starting in "N" and pressing the up or down arrow, the pump will run and the height will raise or lower but it doesn't complete the selection, it'll get to where it wants but the arrow never goes solid and disappears, now not responding to any button press until I restart again, and regardless of whether the truck is High or Low, it displays the "N" symbol and both arrows. The heights of each wheel seem to be out of wack as they are quite different in H setting. To get the truck back to as close to Normal height as possible I have to drive it so it automatically adjusts the height.

After replacing the sensor arm, I connected the truck to Techstream and it had 2 stored DTC's one for the rear right height sensor (which I expected) but also one for the front Left hand sensor. On querying the codes, Techstream reported that there were no faults now, so I cleared the codes. They have not returned and I have not seen any further check 4 wheel AHC warnings (this only happened once on the evening the arm snapped, when going round a bend, driving home).

I have measured the wheel arch clearance from the centre of the arch (perpendicular) to the hub centre and have the following:-

Normal Height Setting
Front Right - 490mm
Front Left - 480mm
Rear Right - 480mm
Rear Left - 485mm

High Height Setting
Front Right - 515mm
Front Left - 560mm
Rear Right - 545mm
Rear Left - 610mm

I have checked all the lines and have no leaks, my fluid level was low in the reservoir, I have topped it up since this happened and not seen any loss since. I also wonder if I have trapped air in the hydraulics somewhere as the tank was low, but I'm a bit nervous about bleeding the system while unable to raise and lower height easily, or correctly. I suspect the fluid hasn't been changed before as the truck is full Toyota service history, and I'm the second recent owner. I think it definitely could do with a new set of accumulators at some point, but I would like to get the height change functionality back up and running first, then do a fluid flush.

Thanks in advance!

 

[lx200inAR]

Hi all,

Been a member of Mud for a long time but not posted in a while, I'm based in UK and own a 2011 european spec 200 series, as you will know these are AHC equipped, as per the LX570's. Hopefully some of you will be able to help as these are pretty rare trucks in the UK and difficult to get anyone experienced with working on them.

Following a recent broken rear right hand height sensor linkage I am having issues getting the system functioning again, I have now replaced the sensor linkage, not the entire height sensor, I suspect it could be out of calibration but hopefully someone with more knowledge of AHC systems than me may have some suggestions?

I can get the AHC pump to run, but only after starting the car, and on the first press of a height selection. For example, starting in "N" and pressing the up or down arrow, the pump will run and the height will raise or lower but it doesn't complete the selection, it'll get to where it wants but the arrow never goes solid and disappears, now not responding to any button press until I restart again, and regardless of whether the truck is High or Low, it displays the "N" symbol and both arrows. The heights of each wheel seem to be out of wack as they are quite different in H setting. To get the truck back to as close to Normal height as possible I have to drive it so it automatically adjusts the height.

After replacing the sensor arm, I connected the truck to Techstream and it had 2 stored DTC's one for the rear right height sensor (which I expected) but also one for the front Left hand sensor. On querying the codes, Techstream reported that there were no faults now, so I cleared the codes. They have not returned and I have not seen any further check 4 wheel AHC warnings (this only happened once on the evening the arm snapped, when going round a bend, driving home).

I have measured the wheel arch clearance from the centre of the arch (perpendicular) to the hub centre and have the following:-

Normal Height Setting
Front Right - 490mm
Front Left - 480mm
Rear Right - 480mm
Rear Left - 485mm

High Height Setting
Front Right - 515mm
Front Left - 560mm
Rear Right - 545mm
Rear Left - 610mm

I have checked all the lines and have no leaks, my fluid level was low in the reservoir, I have topped it up since this happened and not seen any loss since. I also wonder if I have trapped air in the hydraulics somewhere as the tank was low, but I'm a bit nervous about bleeding the system while unable to raise and lower height easily, or correctly. I suspect the fluid hasn't been changed before as the truck is full Toyota service history, and I'm the second recent owner. I think it definitely could do with a new set of accumulators at some point, but I would like to get the height change functionality back up and running first, then do a fluid flush.

Thanks in advance!

The first thing i would do is check what the height sensors are reporting at each corner in Techstream. Possibly one is reading considerably off from the others, making it so the truck can not get the height of that corner where it needs to be (might be reading too high or too low). The pump will only try to adjust for so long, and then as you said, it will continue to attempt to adjust while driving.

You didn't mention whether you had done a fluid flush or not, but that might be the next step once you've determined there are no issues with the height sensors. Most people report the system working faster and smoother with fresh fluid.

 

[GvsB]

The first thing i would do is check what the height sensors are reporting at each corner in Techstream. Possibly one is reading considerably off from the others, making it so the truck can not get the height of that corner where it needs to be (might be reading too high or too low). The pump will only try to adjust for so long, and then as you said, it will continue to attempt to adjust while driving.

You didn't mention whether you had done a fluid flush or not, but that might be the next step once you've determined there are no issues with the height sensors. Most people report the system working faster and smoother with fresh fluid.

 

[GvsB]

Thanks for replying, I did notice in the data that one of the height values was much higher than the others, I'll repeat the check and post the numbers.

I haven't flushed the fluid yet, but want to do that after sorting the height control, then replace the spheres also.

 

[TeCKis300]

I agree that the new sensor installed is probably too far off calibration that AHC is giving up.

The procedure IIIRC to calibrate them is to set the whole car statically at a documented height in the manual and then to initialize the calibration. That's doable but would take some effort and setup.

Using the reported values might be of limited value also as it's hard to know if it's the physical setup, or a sensor bias.

Pragmatically, referencing the current linkage setting, just slide it up 5mm from the current point. If that doesn't work, go 5 mm to the opposite point.

 

[AnyMal]

Yes its most likely too large of a sensor position discrepancy, air in the system at the pump / low fluid would throw a code and lock you out of control completely.
Failing to reach target height is a common issue when sensors are played with. The system is looking for balance and then fails safe prior to restart.

I would also say a good place to start would be to set all sensors in the middle ish positions, do a bleed and fill and purge, then check tech stream readings from there.
Your before adjustment values should be as close as you can get them, then height offset adjust from there. You may need to manually adjust each one from middle at that point if it still fails to cycle. Height offset for the very last fine adjustment to level the rig.

Its finicky, but you should be all good given no codes. Thats where I would start to worry.

 

[GvsB]

I agree that the new sensor installed is probably too far off calibration that AHC is giving up.

The procedure IIIRC to calibrate them is to set the whole car statically at a documented height in the manual and then to initialize the calibration. That's doable but would take some effort and setup.

Using the reported values might be of limited value also as it's hard to know if it's the physical setup, or a sensor bias.

Pragmatically, referencing the current linkage setting, just slide it up 5mm from the current point. If that doesn't work, go 5 mm to the opposite point.

I only replaced the sensor linkage which had broken, not the entire sensor so calibration should be the same unless having a broken linkage can throw the calibration out?

 

[TeCKis300]

I only replaced the sensor linkage which had broken, not the entire sensor so calibration should be the same unless having a broken linkage can throw the calibration out?

I don't know how your linkage failed, but it's possible it failed in a way that tweaked the AHC sensor brackets which can affect its calibration.

 

[GvsB]

Bottom ball joint seized and snapped the arm, noticed something wrong when I lowered the truck to go under a car park barrier and it struggled to go into Low. Then driving home got the check 4 wheel AHC warning. found the sensor had snapped. I'll check the brackets to see if they are bent at all.

 

[lx200inAR]

From your pictures, you can't see where the adjustment is set. But possibly, if it bound enough to break it, it probably pushed itself to one side of the adjuster as well. There is about 20-30mm of play in the adjuster (never measured it...but guessing it's about that much). The slider is on the arm coming off the sensor where the end link connects to it from the control arm.

 

[GvsB]

From your pictures, you can't see where the adjustment is set. But possibly, if it bound enough to break it, it probably pushed itself to one side of the adjuster as well. There is about 20-30mm of play in the adjuster (never measured it...but guessing it's about that much). The slider is on the arm coming off the sensor where the end link connects to it from the control arm.

I think you might be on to something there. When I hooked it up to techstream the value for that sensor was way off the others, I can't remember exactly what, I should have taken a photo of the data. When I fitted the new linkage, I made sure the position of the lower ball joint in the trailing arm bracket was the same, as the opposite side, both were set at the lowest point in the slot.

 

[GvsB]

Thanks for all the replies so far, I will report back when I have more info, I'm not sure if that will be until the weekend as we have a week of heavy rain forecast this week, unfortunately I have to work on the truck on my driveway, not inside.

 

[lx200inAR]

I think you might be on to something there. When I hooked it up to techstream the value for that sensor was way off the others, I can't remember exactly what, I should have taken a photo of the data. When I fitted the new linkage, I made sure the position of the lower ball joint in the trailing arm bracket was the same, as the opposite side, both were set at the lowest point in the slot.

Getting into internet speculations here, but the adjusters aren't usually at the end of the slots. They usually sit closer to the middle. I never remember off the top of my head which direction in the slot lifts and lowers, just know it's opposite front to back, but maybe your truck had been "sensor lifted" in the past.

 

[GvsB]

Getting into internet speculations here, but the adjusters aren't usually at the end of the slots. They usually sit closer to the middle. I never remember off the top of my head which direction in the slot lifts and lowers, just know it's opposite front to back, but maybe your truck had been "sensor lifted" in the past.

I haven't touched the sensors prior to this breakage, but I had looked at the positions, fronts are set to the middle of the slots, rears are set to the bottom of the slots.

For the fronts high setting is the bottom of the slot, for the rears it is opposite, high setting is top of the slot.

So currently my truck bracket positions are fronts set to midpoint, rears set to low, which would bare out as my actual ride heights in 'N' setting are pretty flat and very close, where I think from Factory it should actually be a bit more Stinkbug with the rears set higher than the front. Repeated the 'N' ride heights from my initial post below.

Normal Height Setting
Front Right - 490mm
Front Left - 480mm
Rear Right - 480mm
Rear Left - 485mm

 

[GvsB]

Yes its most likely too large of a sensor position discrepancy, air in the system at the pump / low fluid would throw a code and lock you out of control completely.
Failing to reach target height is a common issue when sensors are played with. The system is looking for balance and then fails safe prior to restart.

I would also say a good place to start would be to set all sensors in the middle ish positions, do a bleed and fill and purge, then check tech stream readings from there.
Your before adjustment values should be as close as you can get them, then height offset adjust from there. You may need to manually adjust each one from middle at that point if it still fails to cycle. Height offset for the very last fine adjustment to level the rig.

Its finicky, but you should be all good given no codes. Thats where I would start to worry.

Hi, I haven't managed to do too much yet regarding your suggestions but I did hook up to Techstream last night so can give an overview of current data set for the height sensors. The readings were taken at 'N' setting. I haven't changed positions of sensors yet, but currently fronts are set to Middle, rears are set to Lowest. Techstream values below (apologies they are in metric). As you will see, they are wildly different! I've attached a photo of the Live data, apologies for the quality, I've only just set techstream up so not sure how to get a screen capture yet.

FR Height control sensor 0.0mm
FL Height control sensor -6.1mm
RR Height control sensor 27.8mm
RL Height control sensor -45.7mm

FR Height Adjust 0.5mm
FL Height Adjust -4.2mm
RR Height Adjust -0.8mm
RL Height Adjust -10.0mm

FR After Height Adjust -0.5mm
FL After Height Adjust -1.9mm
RR After Height Adjust 74.3mm
RL After Height Adjust -81.4mm

 

[lx200inAR]

Hi, I haven't managed to do too much yet regarding your suggestions but I did hook up to Techstream last night so can give an overview of current data set for the height sensors. The readings were taken at 'N' setting. I haven't changed positions of sensors yet, but currently fronts are set to Middle, rears are set to Lowest. Techstream values below (apologies they are in metric). As you will see, they are wildly different! I've attached a photo of the Live data, apologies for the quality, I've only just set techstream up so not sure how to get a screen capture yet.

FR Height control sensor 0.0mm
FL Height control sensor -6.1mm
RR Height control sensor 27.8mm
RL Height control sensor -45.7mm

FR Height Adjust 0.5mm
FL Height Adjust -4.2mm
RR Height Adjust -0.8mm
RL Height Adjust -10.0mm

FR After Height Adjust -0.5mm
FL After Height Adjust -1.9mm
RR After Height Adjust 74.3mm
RL After Height Adjust -81.4mm

View attachment 3319980

So that is saying that the system basically has both the fronts where they expect them but that it thinks the RR still needs to come up 2 more inches. So your sensor is reading low, if the truck is somewhere near where it’s supposed to be.

Also, this part is just a guess, but based on that weird swing in the after adjust value, it looks like possibly the truck over filled that corner and then opened the gate valve between LR and RR and that pressure swung across the axle.

To save you from spinning cycles. The height adjust are a static value that is the factory calibration to get the truck level. These values can be adjusted with the height offset utility. In this case I wouldn’t mess with them, they can only affect the calibration by +-20mm.
the after height adjust is the amount of change each corner experienced after the last change in height.

 

[GvsB]

So that is saying that the system basically has both the fronts where they expect them but that it thinks the RR still needs to come up 2 more inches. So your sensor is reading low, if the truck is somewhere near where it’s supposed to be.

Also, this part is just a guess, but based on that weird swing in the after adjust value, it looks like possibly the truck over filled that corner and then opened the gate valve between LR and RR and that pressure swung across the axle.

To save you from spinning cycles. The height adjust are a static value that is the factory calibration to get the truck level. These values can be adjusted with the height offset utility. In this case I wouldn’t mess with them, they can only affect the calibration by +-20mm.
the after height adjust is the amount of change each corner experienced after the last change in height.

Please bear with me for these questions, I've never had an AHC equipped Cruiser before, went straight from the 80 to a Hilux, then the 200 series, so only learning now something has gone wrong!

So would you mind clarifying how you figured out the RR sensor needs to come up 2 inches because how I'm reading the data the Right side is Plus 27.8mm or 1 ³/₃₂" (approx +1") but the left side is Minus 45.7mm or 1 ⁵¹/₆₄" (approx -2") so the difference between the two is 73.5mm or 2 ⁵⁷/₆₄" (approx 3").

Also, if you recommend I don't change the height offset utility numbers, how do I go about making the adjustments, to firstly bring it back in line and secondly getting the height control to work again I assumed (probably incorrectly) the height sensor adjustments, should be set to the same position across each axle?

Also, just a thought, if the RR sensor is low, I guess this could be because the bracket has been bent down when the sensor arm snapped, the ball joint really is locked solid, so it must have imposed a significant downward force onto the trailing arm bracket?

Thanks again for helping.

 

[lx200inAR]

Please bear with me for these questions, I've never had an AHC equipped Cruiser before, went straight from the 80 to a Hilux, then the 200 series, so only learning now something has gone wrong!

So would you mind clarifying how you figured out the RR sensor needs to come up 2 inches because how I'm reading the data the Right side is Plus 27.8mm or 1 ³/₃₂" (approx +1") but the left side is Minus 45.7mm or 1 ⁵¹/₆₄" (approx -2") so the difference between the two is 73.5mm or 2 ⁵⁷/₆₄" (approx 3").

Also, if you recommend I don't change the height offset utility numbers, how do I go about making the adjustments, to firstly bring it back in line and secondly getting the height control to work again I assumed (probably incorrectly) the height sensor adjustments, should be set to the same position across each axle?

Also, just a thought, if the RR sensor is low, I guess this could be because the bracket has been bent down when the sensor arm snapped, the ball joint really is locked solid, so it must have imposed a significant downward force onto the trailing arm bracket?

Thanks again for helping.

In the current state of N the RL sensor is reading that you are -45.7mm. I'm assuming this is after the truck tried to get to N for a while, so it is probably either sitting high or somewhere near where it should be. Based on how high the RR sensor is showing (up 1"), it's most likely sitting a little proud on what the ECU thinks it should be. I think this, because if the truck is reading that sensor low it would have continued to pressurize that corner attempting to get the height to 0, until it gave up.

You stated the sensors are adjusted to the "truck at lowest position" in rear and based on your measurements that looks correct, since your rear isn't sitting higher than the front by about 25-30mm like it would have been after OEM calibration. (I'm only talking about the measurements you provided here. An OEM calibrated truck should read 0s at all the heights in techstream when in N and in reality, the rear of the truck should be about 1-1.5" higher than the front when it reads all 0s, all of this assuming the truck is on a level plane).

I agree that most likely the arm is bent or is malfunctioning. Also, I don't know where you got the link to replace your broken one, but I assume it's exactly the same length? If it was me and I wanted to try something other than replacing the sensor. I'd make sure the truck is fairly level (the measurements you provided above, with everything within 15mm, I would consider level enough), and I would do my best to adjust that RL sensor to show as close to 0 as possible.

 

[GvsB]

In the current state of N the RL sensor is reading that you are -45.7mm. I'm assuming this is after the truck tried to get to N for a while, so it is probably either sitting high or somewhere near where it should be. Based on how high the RR sensor is showing (up 1"), it's most likely sitting a little proud on what the ECU thinks it should be. I think this, because if the truck is reading that sensor low it would have continued to pressurize that corner attempting to get the height to 0, until it gave up.

You stated the sensors are adjusted to the "truck at lowest position" in rear and based on your measurements that looks correct, since your rear isn't sitting higher than the front by about 25-30mm like it would have been after OEM calibration. (I'm only talking about the measurements you provided here. An OEM calibrated truck should read 0s at all the heights in techstream when in N and in reality, the rear of the truck should be about 1-1.5" higher than the front when it reads all 0s, all of this assuming the truck is on a level plane).

I agree that most likely the arm is bent or is malfunctioning. Also, I don't know where you got the link to replace your broken one, but I assume it's exactly the same length? If it was me and I wanted to try something other than replacing the sensor. I'd make sure the truck is fairly level (the measurements you provided above, with everything within 15mm, I would consider level enough), and I would do my best to adjust that RR sensor to show as close to 0 as possible.

Hi, answers to questions below:-

In the current state of N the RL sensor is reading that you are -45.7mm. I'm assuming this is after the truck tried to get to N for a while, so it is probably either sitting high or somewhere near where it should be.

Since all of this started, I can only get the truck into "N" by driving and the truck automatically adjusting. If I attempt a manual height change it fails, unfortunately I don't have any historical data of the heights prior to the RR Sensor link breaking.

You stated the sensors are adjusted to the "truck at lowest position" in rear and based on your measurements that looks correct, since your rear isn't sitting higher than the front by about 25-30mm like it would have been after OEM calibration.

That is correct, I have never adjusted the height sensors, but as stated rears are currently set to the lowest position on the sliders. It's strange though because before the RR sensor link broke, the truck didn't sit level like it does now, it was always raked nose down as you suggested.

I agree that most likely the arm is bent or is malfunctioning.

I assume you mean the RR trailing arm bracket is bent or sensor malfunctioning? I can confirm, I have checked Techstream twice since replacing the linkage, and no current DTC's.

Also, I don't know where you got the link to replace your broken one, but I assume it's exactly the same length?

I bought a complete Genuine RR Sensor, Part no. 89407-60031. I was going to swap the whole thing but because it is so difficult to release the wiring (in beteen fuel tank and trailing arm to chassis mount), I just removed the new arm from the new sensor and swapped onto the original sensor in place, making sure the adjusting bolt was in back in the same position. The ball joint linkages are identical length.

If it was me and I wanted to try something other than replacing the sensor. I'd make sure the truck is fairly level (the measurements you provided above, with everything within 15mm, I would consider level enough), and I would do my best to adjust that RR sensor to show as close to 0 as possible.

So this is where I'm getting a bit confused, as currently the RR sensor is showing +27.8mm with the adjuster at the lowest setting, so I can only move the slider up, won't that increase the height setting more rather than bringing it down towards zero?

 

[GvsB]

This is the new sensor I purchased before removing the linkage (silver component).