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AHC sensors
- Thread starter Zeusv8
- Start date
It's ok I've done some research through all the LC websites and Lexus lx470 sites and found out that Milners do the sensors for £140/£150 each brand new!! What the hell is Toyota doing charging £315 each for these???? I believe that Milners one come in a Toyota bag from a Japanese factory!!! 
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- Mar 7, 2010
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1: DOn't believe all the codes for ahc. They are most of the time wrong or missing.
2: TC 31 is the front gate valve, which controls body roll in curves. Doesn't seem to have anything to do with your front being high and your rear being low.
TC 31 says "open or short in front gate valve". This can be checked with an ohm meter.
The front gate valve is a part of the ahc valve body; together with front levelling valve, and rear level and gate valves. It is located on the inside of the LHS frame rail, just forward of the accumulator (which is on the outside).
I think it is more likely that the cabling or a plug (e.g. in the dashboard) is at fault, than the actual valve body.
If the situation is that the rear is very low, it is most likely a height sensor fault, and they don't normally give any Trouble Codes.
Some illustrations:
2: TC 31 is the front gate valve, which controls body roll in curves. Doesn't seem to have anything to do with your front being high and your rear being low.
TC 31 says "open or short in front gate valve". This can be checked with an ohm meter.
The front gate valve is a part of the ahc valve body; together with front levelling valve, and rear level and gate valves. It is located on the inside of the LHS frame rail, just forward of the accumulator (which is on the outside).
I think it is more likely that the cabling or a plug (e.g. in the dashboard) is at fault, than the actual valve body.
If the situation is that the rear is very low, it is most likely a height sensor fault, and they don't normally give any Trouble Codes.
This indicates that the height sensor says the rear is 57.4 mm too low. If it isn't than for sure there is a height sensor, cabling or ecu problem.Zeusv8 said:
Some illustrations:
Thanks very much for your reply,but now I'm back to square one!! I think I'll start with the diagnosed sensor and work from there. I think the sensors might be my limit on tackling this problem might be time for an ironman kit if this is the start of more to come!
I have removed,opened and refitted all the sensors on this nightmare vehicle and they are all in mint condition with no corrosion or water ingress.
It's time to re-mortgage the house and go to Toyota with this and get this fully diagnosed and sorted
It's time to re-mortgage the house and go to Toyota with this and get this fully diagnosed and sorted
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Isn't that corrosion on the sliders in the top pic. Need to be cleaner than that.
Frank
Frank
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Those sensors look great.
Your rear height reading from the diagnosis is waay off. When the sensor is in place, and the car is at a normal height level, do you then have the sensor at about middle position? This can be measured as well, either approximately by ohming or with a test set-up with an approx 5 volt supply and a voltmeter.
Your rear height reading from the diagnosis is waay off. When the sensor is in place, and the car is at a normal height level, do you then have the sensor at about middle position? This can be measured as well, either approximately by ohming or with a test set-up with an approx 5 volt supply and a voltmeter.
Those sensors dont look far out from Citroen C5 height sensors, although they will not fit I guess.
When I set the height on the C5 I simply loosen everything up on the anti roll bar, then move the rod going to the sensor untill the car is at the correct height, then tighten up and job done.
Maybe its as simple as this on the Toyota.
All the time these days we rely on diagnostics equipment, only to find that good old fashioned head scratching and common sense is all that is needed.
On another note, I have come up with a very simple 3 page web site just to introduce us to folks that need spheres. It's not flashy with no bells or whistles, but hopefully this is all thats needed.
Regards.
Martin.
http://sites.google.com/site/pleiadessu ... heres/home
When I set the height on the C5 I simply loosen everything up on the anti roll bar, then move the rod going to the sensor untill the car is at the correct height, then tighten up and job done.
Maybe its as simple as this on the Toyota.
All the time these days we rely on diagnostics equipment, only to find that good old fashioned head scratching and common sense is all that is needed.
On another note, I have come up with a very simple 3 page web site just to introduce us to folks that need spheres. It's not flashy with no bells or whistles, but hopefully this is all thats needed.
Regards.
Martin.
http://sites.google.com/site/pleiadessu ... heres/home
It is sitting high at the back or low at the front I'm not sure! The height control button won't let me do anything but yeah it sits in the centre on the rear but I don't have a Voltmeter. If its not a sensor problem is it an Ecu problem? The cables all looked ok around the system.
Hi pleiades I spoke to one of you guys last week about spheres but I don't think that's the problem on this. It won't go up or down on the button and won't self level when it's running and it's probably not a sensor fault by the look of it either!!
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If the back is not low AND the sensor diag reading says minus 57 mm, there is something very wrong back there. It is not uncommon that the sensor linkage gets bent, damaged or stuck (ball-joints).
1
If you detach the sensor linkage from the suspension (bottom leading arm of the rear axle), can you then move the linkage arm and sensor arm freely up and down?
2
And, when the car is at a normal height, will the sensor linkage fit at around the middle of the adjusting slot with the sensor at mid-travel?
1
If you detach the sensor linkage from the suspension (bottom leading arm of the rear axle), can you then move the linkage arm and sensor arm freely up and down?
2
And, when the car is at a normal height, will the sensor linkage fit at around the middle of the adjusting slot with the sensor at mid-travel?
Yes to both, I removed the rear sensor to check it and it was sitting middle and the arms and ball joints are few moving too. The one thing I've noticed is that the system does nothing at all when the engine is running so no noise of the pump trying to level out or any movement just a flashing OFF light on dash. The back might not be low and that it is the front that is high which I'd say is the case as it seems higher when driving.
I've just been to toyota to get a "definitive" diagnostic and it's still a merry-go-round!! Fault code c1731 present(height control solenoid front gate circuit) further investigation needed to diagnose fault! At 62 quid an hour I don't thinkso!!
So does anyone know what/ where this is and can it be repaired cheaply?? Thanks
So does anyone know what/ where this is and can it be repaired cheaply?? Thanks
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There is always a possibility that the pump is not live, or that the pressure sensor is faulty. This can easily be checked. The pump can e.g. be tested with 12 v feed directly for a second.
But,
The rear: When the car is at normal height and the sensor reading says -57.4, which is lower than low, there is something wrong there. That means the ECU gets cr@p in and will give cr@p out. Could you measure the voltage of the centre pin of the rear sensor while it is running? I believe it is easiest to do at the ECU.
On the ECU, the input named SHRR should have 2.5 volts when the rear sensor is at mid-travel. That is pin 2 of plug S8 (that's the middle plug of the ecu). Reference (zero volt) is ground, e.g. pin 7 of plug S7.
The front gate valve can also be checked with an ohm meter. You have to grab the FSM and read a bit. It is very clear on fault finding, just that you have to read a bit in a couple of places, and that's more than the average mechanic can manage.
But,
The rear: When the car is at normal height and the sensor reading says -57.4, which is lower than low, there is something wrong there. That means the ECU gets cr@p in and will give cr@p out. Could you measure the voltage of the centre pin of the rear sensor while it is running? I believe it is easiest to do at the ECU.
On the ECU, the input named SHRR should have 2.5 volts when the rear sensor is at mid-travel. That is pin 2 of plug S8 (that's the middle plug of the ecu). Reference (zero volt) is ground, e.g. pin 7 of plug S7.
The front gate valve can also be checked with an ohm meter. You have to grab the FSM and read a bit. It is very clear on fault finding, just that you have to read a bit in a couple of places, and that's more than the average mechanic can manage.
Ok just so I'm clear on this! I put the red probe of the multimeter on S8 no 2 pin and the black probe on S7 no 7 to get a reading??
I am unsure about the pump test as there are 3 lots of cable connectors that I can see! Do I get 12v to the one nearest the bulkhead which has just 2 wires going to it (e.g two connector blocks are close together and the one near the bulkhead is on its own)I take it I just touch the terminals for a second to see if there is any action from the pump? thanks for your patience!!James
I am unsure about the pump test as there are 3 lots of cable connectors that I can see! Do I get 12v to the one nearest the bulkhead which has just 2 wires going to it (e.g two connector blocks are close together and the one near the bulkhead is on its own)I take it I just touch the terminals for a second to see if there is any action from the pump? thanks for your patience!!James
