Lx470 Stuck in low and Cant Raise Back Up (1 Viewer)

[regularnothing]

Yes Another AHC post

I bought a 1999 LX470 about a month ago and everything was great until it wasn't. Seemingly overnight the rear end had dropped all the way to low and while driving I noticed that the ride quality was getting worse and worse and the back end felt like I was riding on the bump stops. The AHC light was flashing off and I looked in the AHC fluid reservoir the top was a little bubbly/frothy. The day before I had taken off the side steps so I thought that I could have messed up the rear height sensor but it appeared to be fine. So I bought a TechStream cable and hooked it up. I read the codes and got C1751 and C1762 I read somewhere to try and clear the codes and try the active test and it might fix it, so I did that when I tried to raise the back nothing happened and when I tried the front see if it would work it went down but it wouldn't go back up and now the front is on the bump stops too (I think). I tried the active test of connecting a paper clip to Ts and E1 in the diagnostic port under the hood to try and raise the vehicle like that but nothing happened and it didn't work. Next, I cleared the c1762 code again because it kept coming back (The C1751 hasn't come back) and then held the AHC off button and I could hear the pump run for about 10-15 seconds but it made a squealing noise then turned itself off and the c1762 code came back but no fluid had moved in the reservoir and I tried clearing the codes and doing that a couple more times to see if anything would happen and I probably shouldn't have done that because the pump stopped making the squealing noise but I could hear it activate for only like 2 seconds then turn its self off then the c1762 code would come back on TechStream.

After trying to do some research on what the problem is I'm pretty sure there is air in the system somewhere and I'm not sure how to bleed the system to try and get the air out since the car is stuck in low and the posts I've read to bleed the system require you to be able to raise and lower the vehicle and I can't. Also saw a post of someone replacing their pump sub assembly and it fixed it but I'm not really sure where to start and some guidance would be really helpful. One thing to note is that after I bought the car I went on a trip for about 10 days so the car sat for that long in temps of about 25-40 but it still stayed in N height after I got back and it drove fine for about 4 days without the ahc having a problem until I took the side steps off and the next day the back end dropped to low.

 

[GTV]

How rusty is it?

 

[regularnothing]

How rusty is it?

The car is pretty clean underneath.

 

[GTV]

Ok. I see you're from the northeast, rust is an AHC killer.

If it was mine I'd start by pulling the third row seats and any other extra weight you have in there and see if it comes up. If nothing happens give each torsion bar a few turns to take pressure off. Once it comes up bleed the system with new fluid, cross level and correct pressures.

 

[regularnothing]

Ok. I see you're from the northeast, rust is an AHC killer.

If it was mine I'd start by pulling the third row seats and any other extra weight you have in there and see if it comes up. If nothing happens give each torsion bar a few turns to take pressure off. Once it comes up bleed the system with new fluid, cross level and correct pressures.

Thanks I will try that tomorrow. If none of that works is there anything else I should try and do?

 

[suprarx7nut]

I'm guessing you've got a blown globe or two... or four. They're wear components (think of the globe like a shock - needs to be replaced every 5-10 years). When the globes die, they release gas into the fluid. This makes it tough for the system to build pressure and raise itself. It will throw code 1762.

Try bleeding. If you can force the motor to run at least briefly, you can bleed.

Often times when it's stuck in low, it's not completely on the bump stops. If you bleed and see any gas bubbles, you can be pretty sure you've got a dead globe. Buy a set and replace them. $600 or so from Impex. More from ebay. Way, way more from a local dealer. Take your pick and buy a set.

 

[regularnothing]

I'm guessing you've got a blown globe or two... or four. They're wear components (think of the globe like a shock - needs to be replaced every 5-10 years). When the globes die, they release gas into the fluid. This makes it tough for the system to build pressure and raise itself. It will throw code 1762.

Try bleeding. If you can force the motor to run at least briefly, you can bleed.

Often times when it's stuck in low, it's not completely on the bump stops. If you bleed and see any gas bubbles, you can be pretty sure you've got a dead globe. Buy a set and replace them. $600 or so from Impex. More from ebay. Way, way more from a local dealer. Take your pick and buy a set.

Thanks I’m going to try bleeding, is there any specific way I should bleed since I am not able to raise the car.

 

[Malleus]

^this.

I wouldn't personally try to adjust your suspension to repair a problem. Doing so will only introduce more variables into the problem.

Email Dave Stedman at Japan4x4 and ask him to quote you parts. A personal relationship with a real live human professional will result in better experience all around.

 

[Malleus]

Follow the bleeding procedure in the service manual. If you don't have a copy, download one from the Resources forum; don't rely on youtube instructions from someone you've never met.

 

[regularnothing]

Follow the bleeding procedure in the service manual. If you don't have a copy, download one from the Resources forum; don't rely on youtube instructions from someone you've never met.

Thanks. if bleeding doesn’t work. Is there anything else I could try. I’m just thinking of going to a traditional suspension set up because I’m just getting frustrated with the AHC

 

[willyroo]

Thanks. if bleeding doesn’t work. Is there anything else I could try. I’m just thinking of going to a traditional suspension set up because I’m just getting frustrated with the AHC

You should persist and get this sorted.

My previous LC was standard suspension, my LX has AHC. Just night and day in terms of off road capability, comfort and quietness.

 

[regularnothing]

You should persist and get this sorted.

My previous LC was standard suspension, my LX has AHC. Just night and day in terms of off road capability, comfort and quietness.

I really do want to keep the AHC but I feel like after I try to bleed the system nothing is going to change. I don’t feel like spending a ton money throwing new parts at it trying to fix it just for it to not work when that money could have gone to a traditional suspension.

 

[Malleus]

Take a break and go at it tomorrow. There's nothing like frustration to aid failure.

Anything that's failed can be fixed, and it'll take much more time, effort and money to remove the AHC system and replace with the Land Cruiser suspension.

 

[suprarx7nut]

Thanks. if bleeding doesn’t work. Is there anything else I could try. I’m just thinking of going to a traditional suspension set up because I’m just getting frustrated with the AHC

I really do want to keep the AHC but I feel like after I try to bleed the system nothing is going to change. I don’t feel like spending a ton money throwing new parts at it trying to fix it just for it to not work when that money could have gone to a traditional suspension.

I don't mean this in an offense way, but more of a coach or mentor.

This is what I hear you saying:

You don't need to fully raise to bleed. You only need to bleed a tiny bit because as soon as you see bubbles come out of the tube, I'm guessing you'll see frothy/bubbly fluid and you'll know immediately you need globes. Try each corner and report back. Take pics. Lots of em.

After that you can diagnose more.

AHC is not impossibly complex, but it does require some effort and careful thought. At least do the basic troubleshooting before dropping a ton of money on a downgrade conversion. If you're willing to put up with the diagnostics (really not that hard in 90% of cases, just takes more mental effort than old-school car mechanics), then you can enjoy a top notch suspension system.

 

[2001LC]

There are other issues, you may have. But "bump stop ride", was a big clue! So I'd start with inspecting globes:

As @suprarx7nut first stated. Likely your globes. Since you already stated you looked at rear high sensor. If came loose in slide, it slide up and down freely. This doesn't usually result in bump stop ride. But can result in to much pressure on old rear globes, resulting in a rupture.

You stated riding like on bump stops in rear. Which is how they feel when a globe ruptures. So very likely one or both rear globes ruptured.

Often I find which globe ruptured. By driving over a speed bump, one wheel at a time. Vehicle becomes unstable, when wheel/tire of rupture globe goes over speed bump.

When when a globe ruptures. The remain nitrogen gas is released into system, and fluid enters the globe. Which, we often then find debris in the system from ruptured bladder. A test, if you can bleed some off. Will be debris in rear fluid, found in your catch can, when filter through a rag.

Best to flush (bleed) a few times, after new globe installed. I, filter new fluid on second bleed and recycle it. Or use multiple 2.5L cans.

Warning: Do not use 1L plastic bottles. They may have jelled.

 

[J1000]

Frothy fluid in the reservoir is definitely an indication of a blown globe. New globes, new pump, and fluid comes out to less than $1000 and is considerably easier than replacing the t-bars and rear springs and then adding traditional shocks.

The pump is super easy to replace and the globes are easier.

 

[tjb]

I thought I may have blown a globe last winter but the car stayed at N and I kept riding it. About a month ago, I got the blinking off and set to L.

Last night, at about 0 degrees Fahrenheit, the truck suddenly went way down in the back.

I swapped my globes out with new ones from Impex a couple years ago, and promoted the price here. Has anyone else had any issues with blown Impex globes?

How dangerous is it to continue to drive in this condition?

 

[Rhetoric]

I thought I may have blown a globe last winter but the car stayed at N and I kept riding it. About a month ago, I got the blinking off and set to L.

Last night, at about 0 degrees Fahrenheit, the truck suddenly went way down in the back.

I swapped my globes out with new ones from Impex a couple years ago, and promoted the price here. Has anyone else had any issues with blown Impex globes?

How dangerous is it to continue to drive in this condition?

You might need your own thread that has more info on what your pressures were after globes etc/etc/etc.

Don't risk other's lives on the road when you know your truck has a suspension issue. Please.

 

[GremlinMobile]

Following this thread so I can learn from it. But also wanted to add - I'm pretty sure half of us here are driving around with bad globes but that doesn't result in what you're seeing. I don't believe in coincidences so I think you must've hit something when removing the side steps and that probably opened up the system, releasing some fluid out (which explains why the rear is now low) and introducing air into the system (which explains frothy fluid in the reservoir and pump unprimed and unable to work)

 

[J1000]

I thought I may have blown a globe last winter but the car stayed at N and I kept riding it. About a month ago, I got the blinking off and set to L.

Last night, at about 0 degrees Fahrenheit, the truck suddenly went way down in the back.

I swapped my globes out with new ones from Impex a couple years ago, and promoted the price here. Has anyone else had any issues with blown Impex globes?

How dangerous is it to continue to drive in this condition?

Have you replaced the pump? My guess is the pump went out, not the globes.