Did you try priming the pump on your bench? Or cracking the lines after the pump? Just curious.
HELP Needed AHC 2010 LX570 (5 Viewers)
- Thread starter Solboricua
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- Thread starter
- #42
No but I will def do this once the new pump is here. I am thinking new OEM shocks, new globes and now new pump...almost all the system will be new. But I do think that in another situation I might just have swapped the suspension for the regular Land Cruiser set up. I am sure the work would have been extensive but I figured let’s give it one last chance. Fingers crossed.
You still bleed the 5th accumulator right?
Does the old pump still pump fluid when powered up?
Does the old pump still pump fluid when powered up?
@turbo8 has done a full swap and managed to eliminate all the dashboard lights. But sounds like you are on the right path. Sounds like you already paid for a new pump, so might as well use it, but I would try priming the one I had. From the previous thread on the pump tear down, it appears to be a pretty robust unit.
- Thread starter
- #45
New Updates: worked and now not working.
1) Installed the new pump and bleed as described. Worked perfectly and the car went up and down. Decided to take it for a stroll and see the drive ability. Perfect. Was ordering the kids some food and playing with the 4Hi and 4 Low and then the infamous "Check AHC system" light came up, with no problems on the car whatsover.
2) Went home and the same code came up, C1763. Cleared it and turned on the car and the code came up again. At this point the car does not want to go up or down, stays in Neutral.
3) Decided to bleed the system to see if that would remidy the situation (per the manual). After bleeding the car went down a little but now its stuck in the lower position from bleeding. I did also bled the 5th unit height control accumulator.
4) One thing that I noticed is that the fluid level on the reservoir did not change in height, before I would add fluid and it would spread it accordingly and the level would go down. Now the pump primes and does not decrease in the oil level. I thought, well there has to be an obstruction so I disonnected the pump and turned the car on and it started pumping out fluid perfectly.
5) Now that I know the pump is not the issue, I am assuming that there might be an obstruction somewhere. I was thinking of following the metal pipe from the pump to the location (I think it connects to the AHC valve, disconnecting it and blowing compressed air to see if something is obstructed. Please note that the height accumulator (the one next to the exhaust) is not discharging any fluid now. I am thinking there has to be an obstruction somewhere before the 4 corners to not let the oil go to the central unit.
Any help would be highly appreciated.
1) Installed the new pump and bleed as described. Worked perfectly and the car went up and down. Decided to take it for a stroll and see the drive ability. Perfect. Was ordering the kids some food and playing with the 4Hi and 4 Low and then the infamous "Check AHC system" light came up, with no problems on the car whatsover.
2) Went home and the same code came up, C1763. Cleared it and turned on the car and the code came up again. At this point the car does not want to go up or down, stays in Neutral.
3) Decided to bleed the system to see if that would remidy the situation (per the manual). After bleeding the car went down a little but now its stuck in the lower position from bleeding. I did also bled the 5th unit height control accumulator.
4) One thing that I noticed is that the fluid level on the reservoir did not change in height, before I would add fluid and it would spread it accordingly and the level would go down. Now the pump primes and does not decrease in the oil level. I thought, well there has to be an obstruction so I disonnected the pump and turned the car on and it started pumping out fluid perfectly.
5) Now that I know the pump is not the issue, I am assuming that there might be an obstruction somewhere. I was thinking of following the metal pipe from the pump to the location (I think it connects to the AHC valve, disconnecting it and blowing compressed air to see if something is obstructed. Please note that the height accumulator (the one next to the exhaust) is not discharging any fluid now. I am thinking there has to be an obstruction somewhere before the 4 corners to not let the oil go to the central unit.
Any help would be highly appreciated.
Edit: Realized there is a big flaw in my logic. It’s treating the accumulator as a static volume reservoir, rather than dynamic that is always under quite a bit of pressure. So the only way any of the below makes sense is if there is any dead space that air/or fluid that isn't under pressure could get into within the accumulator.
The accumulator only empties when you go from L -> N or from N -> H. If you "bleed" or empty it, it will not refill on it's own. It is my understanding that it will only refill after a raised vehicle event. So if you are not getting a successful " L -> N" or "N -> H" you won't get the accumulator filled.
I've read the FSM and AHC description docs a few times now, and this is my interpretation. Take it for what it's worth.
C1763 triggers when the AHC system fluid pressure is below 87 PSI for .6 seconds while the pump is running. To me, if you clear this event and it comes back, then you probably don't have enough pressure in the system to not trigger that alert. I'm not sure if there is 0 PSI (eg. from disconnecting the pipe) that the pump can generate 87 PSI (this is a pretty big number in pneumatics but not so much in hydraulics) in the .6 seconds. It could be that sometimes it does and sometimes it doesn't . If this is the case, then clearing the alert and then forcing a raise with the AHC Test utility in Techstream should cause the pump to run enough to get past the 87 PSI threshold. Should be able to perform the test on any corner to get the pump going. Alternatively, hitting the Lift button after a restart before the AHC has a chance to complete it's self test may also solve the problem. So clear the alert, restart the truck and before AHC light has a chance to go off use the lift button.
It doesn't sound like there is a clog because there are codes C1764 / C1765 that are triggered when there is more than 2683 PSI for .3 seconds recorded on the AHC system pressure sensor. Unless the clog is in front of the sensor (note: the sensor is part of the pump mechanism which is before the pipe you are planning to clean out).
The other piece to this puzzle that I may be confused about is the accumulator. If you drain the accumulator but the truck "thinks" it is full (eg. by bleeding it), when you go to raise the vehicle the ECU is going to open the accumulator valve to help raise the truck. In reality what will happen is the accumulator will need to fill with fluid first before any pressure will build up in the system. This may be the cause of the C1763 code. When the truck opens the accumulator to find that it's not under pressure and has to pressurize it, the pressure on the sensor falls below 87psi and the DTC gets thrown and the pump shuts down. I can't find any documentation that shows that there is a sensor on the accumulator to notify the AHC ECU of whether or not it is storing pressure before it opens the valve. (Edit: The accumulator is under pressure from a nitrogen gas chamber charged to 856PSI (5.9 MPa). I assume this means that fluid won't even start filling the accumulator until pressure in the system pushes over this).
With the above in mind, you may have to repeat the steps to get the accumulator full enough to stop triggering the DTC.
OF course all of this is ignoring the fact that you had it working and then it stopped working. So I suspect there is more to the story. Your issues are mirroring another forum members. He took apart his pump and cleaned it and verified it was working. Put it in the truck, everything worked great for a few days then it stopped working.
The manual states any time you do a lift, you should let the truck run for 25 seconds to let the accumulator recharge. I wonder if people are running into an issue where they are playing with the up/down buttons and then turning the truck off only to come back to a DTC waiting to happen, because possibly they raised the truck using up the stored accumulator pressure but did not give the pump time to refill the accumulator. I've read on this forum that the accumulator only fills on a N->H maneuver, but I don't know if that makes much sense. Then people who use "easy access" mode would never be raising the truck off the accumulator when going from L -> N every time they restart.
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Another thought to add to the long post above. When moving the truck up or down the leveling valves also open. I suppose if there was any free space there that would allow the pump to be active without creating enough pressure, but if you aren't sitting on the bump stops then there should be pressure behind the leveling valves already. Also, if there was still pressure in that part of the system, I would assume that it would push back towards the pump and into the accumulator until the accumulator was full. If any of these assumptions are correct, then using Lowering to flow fluid back towards the accumulator might speed up the whole process.
The accumulator has a volume of 1 liter, so I could see it taking a while for the pump or backflow from suspension to fill that up. I'm not sure what the flow rate of the AHC pump is.
The FSM provides a pretty good bit of detail about how the system generally works, but it would be cool if we could uncover a bit more of the mystery about what inputs the AHC ECU uses to decide which valves to open. That's the glaring hole in the FSM. Every valve descriptions basically ends with..."in accordance with the signal received from the suspension control ECU." Would be nice to know how it makes its decisions. You can piece some of it together with the FSM troubleshooting guide for DTCs.
The accumulator has a volume of 1 liter, so I could see it taking a while for the pump or backflow from suspension to fill that up. I'm not sure what the flow rate of the AHC pump is.
The FSM provides a pretty good bit of detail about how the system generally works, but it would be cool if we could uncover a bit more of the mystery about what inputs the AHC ECU uses to decide which valves to open. That's the glaring hole in the FSM. Every valve descriptions basically ends with..."in accordance with the signal received from the suspension control ECU." Would be nice to know how it makes its decisions. You can piece some of it together with the FSM troubleshooting guide for DTCs.
- Thread starter
- #49
First and foremost thanks so much to you and this entire community for the help.
-I have hit the test AHC utility and neither the front or rears go up, even when using the go up with accumulator. I have also turned the car on and hit the Up botton to get the car up before the "check AHC system" and the pressure goes up to 2.75 and the code comes up again. I am not able to lift the car up or down using this method.
So there are 2-3 threads going with similar issues right now. I believe one person found that vacuum in the reservoir was keeping his pump from being able to feed the hydraulic lines with fluid. He opened the reservoir fill hole while the truck was lifting and this allowed the pump to work. I’m not sure if this is a permanent fix, but maybe getting the system going and full without air, then there won’t be a vacuum issue.
I wouldn’t be worried about the accumulator not helping, since it probably has no pressurized fluid in, and won’t until get the pump going again.
I wouldn’t be worried about the accumulator not helping, since it probably has no pressurized fluid in, and won’t until get the pump going again.
- Thread starter
- #51
I agree. I tried that this morning and the code 1763 comes up right away when I remove the reservoir fill plug. One thing to note is that when I removed the hardline from the pump I heard alot of bubbles coming from the pump and no fluid coming out of the hardline hole. I think that the system is trying to pump againts air in the hardline. I tried to open the union nut (there are 2) but the locations are almost impossible to access. The one next to the pump is a 10mm and did not budge also the small space did not allow an open wrench to fit so I had to use one of the smallest 4 inch wrench and I was not able to open the line. The second union nut next to the actual muffler of the car is a 14mm if I remember correctly but again no space to work or move the wrench. I might have to remove the muffler to crack that line open.
This is getting into wild speculation on my part, but if you need to "crack a line" easily because you think it's pushing against air, possibly open a bleeder or two at the wheels? Maybe on the same axle. If that seems to help, maybe do all four? I don't know though, the manual certainly never suggests that and i'm not a hydraulics specialist.
I will say this though, Code C1763 doesn't suggest to me that you are pumping against air. For one thing, even if the system was completely full of air (at atmospheric pressure, the air would compress and not stop the fluid from entering.
The other guy that is having the same issue as you, complete with the step of it worked for a bit then stopped working said that he found an issue with his AHC fluid. Said the fluid was "hazy" and this possibly caused his pump to be stopped up on the intake. I've included the link for the fluid pictures, but I'd definitely read through that hole thread for some insight.
forum.ih8mud.com
I will say this though, Code C1763 doesn't suggest to me that you are pumping against air. For one thing, even if the system was completely full of air (at atmospheric pressure, the air would compress and not stop the fluid from entering.
The other guy that is having the same issue as you, complete with the step of it worked for a bit then stopped working said that he found an issue with his AHC fluid. Said the fluid was "hazy" and this possibly caused his pump to be stopped up on the intake. I've included the link for the fluid pictures, but I'd definitely read through that hole thread for some insight.
AHC Pump Fun - Disassembly and Clean - Verbose Edition
Stumbled on this thread that is a few years old. It has pictures of the filters removed from the pump housing. Sounds like the OP destroyed the filter trying to remove. So i guess if you don't have replacements, i wouldn't try removing...
forum.ih8mud.com
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When I replaced the hard line in mine I had enough space at the second union. You need two wrenches, one to hold the bracket and the other to loosen the nut. You need to remove the spare. I didn't need to lower the muffler until it was actually time to remove the line, but you can unhook the muffler from the last three rubber hangers and let it drop a bit if you need more space.
any new updates @Solboricua? i’m experiencing the same issues as you post bleed and replacement of two front struts. the only difference is i’m not doing the work and my rig is with longo lexus dealer. i’ve been following along and want to know if you remedied the lack of pressure. the tech / engineer is on the 3rd pump but same symptoms as you were describing. they had the lx for two weeks now
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- Thread starter
- #55
Unfortunately no new developments. I took the pump off the car and it started to make noises like bubbles, completely disconnected. I talked to the people who sold me the pump in MD and they are willing to refund my payment. Thinking of just going for a normal non-hydraulic suspension.
In case you aren't following this thread..
forum.ih8mud.com
HELP! AHC Pump Issue After Reservoir Drain/Refill
forum.ih8mud.com
@lx200inAR I saw this (thank you) and called my dealer right away. Now it’s convincing them to investigate the clog by opening the pump - while mom and pop shops are open to this approach, dealerships normally remedy issues by buying new partsIn case you aren't following this thread..
HELP! AHC Pump Issue After Reservoir Drain/Refill
I forgot to mention Longo Lexus is exploring alternative suspension fluids. If all else fails I’m going to explore deleting the AHC and going with a more traditional suspension. Anyone want to start a class action lawsuit against the supplier?
i know its been like 4-5 years but did you end up fixing the problem?
