- Thread starter
- #21
I’ll try bleeding now. Ran for maybe 15-20 seconds or so while I held it down
AHC failure only after flush
- Thread starter AClarko
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- ahc failure lx470
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Do you have the pages from the code 1762? The one you posted is similar, but not quite what @AClarko needs if the pump runs.
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- #23
Ok an inch worth of clear fluid came through the tube. Looks like there was an air bubble as well.
So should I keep repeating this (SST and same front driver side) or repeat the SST and move to the next corner and keep alternating?
Awesome. Every air pocket moved out is one step closer to solving this.
I would try bleeding the other side before you doing another round, but then I'd repeat the process over and over until no air comes out. Run the pump for ~30-45 seconds, then bleed each side of the front. Repeat until no air comes out. At which point, I suspect you'll start to see the vehicle raising.
Here ya go
If the pump is running but you’re not getting fluid through the system it could be that there is a clog somewhere. Might want to take a look at this thread HELP! AHC Pump Issue After Reservoir Drain/Refill - https://forum.ih8mud.com/threads/help-ahc-pump-issue-after-reservoir-drain-refill.1261668/
This is a good point. The screen(s?) in the pump could be clogged up with gel. Since that's a more invasive fix, I like the bleed process as a first course of action, but the gelled up screen is good to be aware of should bleeding show only fluid.
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- #28
Okay, I ran the pump another 30 seconds and then moved to the rear passenger side. A small amount of fresh fluid came out with a bubble.
I am going to continue this tomorrow morning as it started raining.
Questions before I continue:
How soon after I see fluid come out of the bleed screw should I close it again? For the rear one a very small amount came out and stopped before I shut the valve, is this too late? Do I need to close it as the stream is moving out?
Should I try bleeding the accumulator in this process as well? I think I am in this mess because of the accumulator, I think I opened the bleed screw too much for too long when I didn't see the vehicle lower at all.
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- #29
I can't rule out a clogged pump..
but when I removed the old fluid from the reservoir and put in the new fluid it worked fine. the vehicle raised and lowered. It was only after I flushed the accumulator and front driver side actuator when the car would no longer raise. I also did them at the same time without turning it on again.
I am thinking I definitely just introduced air through the accumulator, as I thought the vehicle was supposed to lower, so I kept it open too long.
Focus on the front first. The way the manual reads, I suspect the rear valve is closed so any fluid movement there is relatively trivial at this point. It should all be up front.
Closing the bleeder should be done right when the flow stops. Crack it open, flow starts and eventually stops (usually abruptly). Close the bleeder then. It's not critical to time it well if your bleeder hose is sealed and filled with fluid. If the bleeder hose is not sealed or full of air then timing becomes critical. Make sure your hose is a good fit.
I would not bleed the accumulator now. Later, definitely. For now, focus on ridding the fronts of any air and getting that pump quieted down and acting normal. Then you will proceed to bleed the rear and accumulator.
Yup, sounds like air went back into the accumulator. Another member did the same exact thing months ago. Just needed a lot of bleeding to correct it.
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- #31
Last night while doing the SST, when I was pressing the "up" mode I didn't really hear the pump "whine". Normally every time I started the car the pump would whine for about 30 seconds. Very audibly.
Last night I expected to hear a whine in SST but thought it was doing something because when I pressed "up" I got a slight dim on the interior light, and a very slight sound from the pump. Had to focus to hear anything. I assumed this was good though and the pump was doing something although silent, because I saw a little fluid when I went to drain. I thought I was making progress, but it was such little fluid the level change was unnoticeable in the reservoir. Maybe an inch or two flowed through the tube when bleeding.
I think I took a step backwards because today when i tried the SST, I dont think I'm getting any action at all from the pump. And now when I turn the car on (just normally when I don't short the pins for SST) the pump doesn't whine. It just immediately flashes off. It used to try to engage for 30 second or so.
The pump used to whine when the car started now it doesn't, may the pump actually be shot? No real change in reservoir level.
Could be clogged. The strainers can clog with gel. Might be time to buy some orings and try opening it up. Annoyingly more invasive.
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Additional thoughts now that I'm at a keyboard and not on the move.
A very quiet AHC pump is normal. Between the brake booster and engine noise it can be tough to pick out the AHC pump. It should be rather quiet. Of course, a pump with heavily eroded gears would probably also be quiet, but nobody has seen that on an AHC pump so that seems unlikely enough that we can practically disregard it.
Dimming lights when the pump kicks on: I've never experienced that. Any chance the car has a dying battery? Are your windows slow to roll down/up? That sounds like a general electrical issue more so than anything AHC specific.
Immediate AHC off light: The trigger sequence for the oil pressure trouble code (1762) is a pressure change less than .5Mpa in 0.6s. All it needs is .6 seconds. At that point the pump is disabled. Arguably this is a poorly chosen behavior since allowing the pump to run a short while longer may move air pockets enough to avoid the "dead AHC" situation. I assume the design engineers limited it to this timeframe to prioritize pump health. In reality we see far more people with bleeding problems and the flashing AHC off light than we do with dead pumps so I think it's a good argument to say the engineering design was overly cautious.
At any rate. Reservoir level may not move much if the pump still has a little air. Please clarify what happens when you use the SST sequence to force the pump to run.
Does it cause the pump to turn on?
If you have a hard time hearing it, are you letting the car warm up enough for the engine fan to quiet down?
I had a similar problem, but not during the bleed but soon after doing some off-road. I believe the pressures were just near the max allowed at the front actuators and the off-road shenanigans pushed it past that threshold causing the exact problems you're having. I resolved this by simply cranking the torsion bars up a couple turns on the drivers side. Now it will be difficult to turn since your LX is stuck on L, but it will be doable. You should get immediate results after. Mine was flashing the light and the pump would only engage for maybe 10-15 seconds as well before it shut off, and after awhile, it just stopped turning on altogether. But once I cranked the torsion bar up, it worked immediately. You can do a search on google or here on the process of adjusting the torsion bars. It is recommnended that you use techstream in conjunction so you know what the exact pressures are at each corner, but just for getting the AHC to be functional again, cranking the bars works just fine. I still haven't used techstream to ascertain the exact pressures but I've gone on a few rougher off-road trips after making the adjustments and I haven't had it fail since.
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- #35
When I go to SST I can never hear the pump.
To confirm the pump worked I put power to it manually, it works I can hear it whine. In SST I do not hear the whine of the pump.
While powering the pump manually I cracked the line off the pump and fluid came through. Also, while having a helper power the pump manually I went to the 4 actuators and cracked them to see if fluid moved through the system. Clear fluid came through. I tried this multiple times each actuator, fluid was clear, no bubbles, although it came through slowly. I thought this may be a good way to bleed the system of air and check to see if fluid moved through the pump.
With this, would you eliminate the pump being clogged/bad?
However, when I tried this with the driver side actuator, I did not receive the same flow. Some fluid seeped out with some bubbles and then stopped. I am not able to cycle fluid through like I was able to with the other 4 actuators. I am not sure if there is some valve or something and this is normal behavior if the car is off and powering the pump manually though.
Where would you go from here?
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- #36
I think I may have terms mixed up. Referring to the driver side large Height Accumulator that does not bleed. The other 4 actuators do when I power the pump manually.
I know I'm out of the loop but have you scanned the ahc controller with techstream to see what the ride height sensors are reading. Could be a chance that when the suspension bottomed put maybe a ride height sensor failed and is causing a failure state. Also attempt bleeding the ride height accumulator first as that will make the empty individual accumulators a bitch.
Ah, that makes sense. The height control accumulator has a solenoid valve that's normally closed. It's only open when filling or raising. So your experience makes sense. That's how it should behave. To bleed the HCA you need to let the system charge it up. This is easy to verify by sound or Techstream.
