Sudden AHC failure and leak (1 Viewer)

[Tbay LX]

From everything I've read, AHC tends to give warning before failing. I've left my truck sitting at a friends house since Christmas, as I'm currently living out of town and only back here a couple weeks every two months or so. Anyway, I drove it back to my hotel from his place last night, and noticed the ride getting progressively bouncier. When I got out(8 km), I noticed the back end was sagging. The AHC light hadn't gone on at any point, though the ABS light was on since we started it (the battery had been disconnected while I was away). Started her up this morning, (ABS light off AHC Light on) popped the hood to check the AHC reservoir, and it was empty.... Looked under the truck, and there was a puddle on the drivers side, near the door.
I'm not sure what to do at this point. I just had the timing belt and water pump done maybe 1000km ago. Breaks and a U-joint (spider joint?) were replaced about 250km ago, just before I was in town for Christmas. Any chance these issues could be related to that work being done? The mechanic is very good, but not a Toyota guy. The truck drove fine over Christmas, except for the weird electrical gremlin mentioned in my previous post.
As much as I love this truck, I can't keep dumping money into something I only drive a couple weeks every couple months. What would be the cheapest AHC replacement option? I'd love to do an OME lift, but it just doesn't make financial sense for me right now. The truck's got 350,677km on it, for those wondering about AHC failures...

Also, I should mention, when we first put the battery in and started the truck there was some sort of burning, electrical smell, but it went away eventually. And... My exhaust pipe seems to have cracked while the vehicle was sitting unused... FML

 

[Ramathorn15]

From everything I've read, AHC tends to give warning before failing. I've left my truck sitting at a friends house since Christmas, as I'm currently living out of town and only back here a couple weeks every two months or so. Anyway, I drove it back to my hotel from his place last night, and noticed the ride getting progressively bouncier. When I got out(8 km), I noticed the back end was sagging. The AHC light hadn't gone on at any point, though the ABS light was on since we started it (the battery had been disconnected while I was away). Started her up this morning, (ABS light off AHC Light on) popped the hood to check the AHC reservoir, and it was empty.... Looked under the truck, and there was a puddle on the drivers side, near the door.
I'm not sure what to do at this point. I just had the timing belt and water pump done maybe 1000km ago. Breaks and a U-joint (spider joint?) were replaced about 250km ago, just before I was in town for Christmas. Any chance these issues could be related to that work being done? The mechanic is very good, but not a Toyota guy. The truck drove fine over Christmas, except for the weird electrical gremlin mentioned in my previous post.
As much as I love this truck, I can't keep dumping money into something I only drive a couple weeks every couple months. What would be the cheapest AHC replacement option? I'd love to do an OME lift, but it just doesn't make financial sense for me right now. The truck's got 350,677km on it, for those wondering about AHC failures...

Also, I should mention, when we first put the battery in and started the truck there was some sort of burning, electrical smell, but it went away eventually. And... My exhaust pipe seems to have cracked while the vehicle was sitting unused... FML

Since its near the door, it sounds like its probably from the accumulator or lines associated with it. I would crawl under and take a look at where its leaking from. Either way, its likely going to be more expensive than just swapping in a LC suspension. I think all you would need are 4 shocks and rear coil springs from a LC to do a swap.

 

[kusok]

Mine also failed suddenly. One day, was going home from work, started the truck up and right in the parking lot while stationary, the AHC went into low and OFF started blinking. That was the end of it. AHC was working fine up to that point. Turned out to be rusted read accumulator.

The trouble is when it happens, the pump works without fluid and likely is damaged, so probably its cheaper if you replace with non AHC (this is what I did).

 

[PADDO]

From everything I've read, AHC tends to give warning before failing. I've left my truck sitting at a friends house since Christmas, as I'm currently living out of town and only back here a couple weeks every two months or so. Anyway, I drove it back to my hotel from his place last night, and noticed the ride getting progressively bouncier. When I got out(8 km), I noticed the back end was sagging. The AHC light hadn't gone on at any point, though the ABS light was on since we started it (the battery had been disconnected while I was away). Started her up this morning, (ABS light off AHC Light on) popped the hood to check the AHC reservoir, and it was empty.... Looked under the truck, and there was a puddle on the drivers side, near the door.
I'm not sure what to do at this point. I just had the timing belt and water pump done maybe 1000km ago. Breaks and a U-joint (spider joint?) were replaced about 250km ago, just before I was in town for Christmas. Any chance these issues could be related to that work being done? The mechanic is very good, but not a Toyota guy. The truck drove fine over Christmas, except for the weird electrical gremlin mentioned in my previous post.
As much as I love this truck, I can't keep dumping money into something I only drive a couple weeks every couple months. What would be the cheapest AHC replacement option? I'd love to do an OME lift, but it just doesn't make financial sense for me right now. The truck's got 350,677km on it, for those wondering about AHC failures...

Also, I should mention, when we first put the battery in and started the truck there was some sort of burning, electrical smell, but it went away eventually. And... My exhaust pipe seems to have cracked while the vehicle was sitting unused... FML

How bad is your underside corrosion? You've possibly had a hydraulic line or union rust through, and the general area you describe has the height accumulator, a damper assembly and the main valve block so there are a few lines and unions. You'll need to identify where and what has failed so it can be repaired or replaced. A decent hydraulics fitter could sort out most issues with corroded lines and fittings. I doubt your pump is U/S, it's a simple gear pump and you'd damn near need to run sand through it to hurt it, plus the protection circuits should have saved it from constant running too.

 

[Tbay LX]

There's a fair bit of underside rust, that's what scares me off of spending the cash to keep building this thing. A fitting or line sounds ideal, I imagine that'd be a pretty affordable fix. too bad all that new fluid went to waste, I just flushed it a year ago... It's so hard to get under the vehicle now with all the snow on the ground, and its new low rider stance.

How bad is your underbod

How bad is your underside corrosion? You've possibly had a hydraulic line or union rust through, and the general area you describe has the height accumulator, a damper assembly and the main valve block so there are a few lines and unions. You'll need to identify where and what has failed so it can be repaired or replaced. A decent hydraulics fitter could sort out most issues with corroded lines and fittings. I doubt your pump is U/S, it's a simple gear pump and you'd damn near need to run sand through it to hurt it, plus the protection circuits should have saved it from constant running too.

 

[Tbay LX]

Not sure if these photos are any help. It's a bit tight under there. Looks like the accumulator and globes are pretty dry. I really can't tell where the leak is though.

 

[Ramathorn15]

Hmm. Only way I can think of to really find the source of the leak would be to add fluid to the reservoir and let the truck try to level itself while you look in the general area for the leak. If you do that, make sure you clean the area with brake cleaner fist, and wear safety glasses in case the fluid squirts out.

It could be a simple hose, but its impossible to tell unless you really pinpoint the leak.

 

[Tbay LX]

Good call. I think I still have some fluid left from the flush. Is there any danger to the AHC letting the pump run like that? Any idea how much fluid I'll need to put in? I don't want to waste it, that stuff ain't cheap, or easy to get up here, damn Canadian dollar.

 

[SWUtah]

Just have the AHC disconnected add the LC springs and shocks and put a piece of tape over the AHC light on the dash. Cheapest fix.

 

[Ramathorn15]

As long as there is fluid in the system, it shouldn't be a problem. As another member mentioned, the pump should have a safety shut off if it senses loss of pressure. I can't verify that though.

If it were me, I would hammer that area with brake cleaner, let it dry, check to make sure I didnt miss any spots, then pour maybe 100-200mL in the reservoir, check again before starting to see if anywhere is actively leaking. If I couldn't pinpoint the leak, I would then have someone start the car while I laid under and look for the leak. Make sure the person you have start the car knows to turn the car off as soon as you say so. If you can't find the leak after a decent bit of fluid has drained out, stop and try again.

 

[Ramathorn15]

Just have the AHC disconnected add the LC springs and shocks and put a piece of tape over the AHC light on the dash. Cheapest fix.

Probably right, but if its just a metal line, it could be fixed for pretty cheap. You could probably buy a flange tool, bender, and all the line you need for under $40.

 

[Tbay LX]

Okay, thanks a lot guys, I'll get to it over the weekend and report back. I'd honestly love to rip out the AHC and put in traditional suspension. That was always my plan for this rig. But, because of certain life events, I'm now living between two cities, and only drive the LX when I'm here for work. The last three trips I've been back, there's been a new problem each time. I'm afraid that if I put more money into this thing, on my next trip it will be undrivable for some new reason. You guys can see how much rust there is, I'm starting to think this particular LX may be a money pit. In fairness, I only paid $4000 for her, and have put in maybe another $3000 including tires, timing belt etc. Done some wheeling, made 3 years worth of great memories. I'd say that's a solid return on investment (too bad the timing belt and breaks were just within the last 1000K). I really don't know what to do... I love this truck.

 

[PADDO]

It certainly appears as if the fluid is coming from the control valve assembly area and if your pump did run dry then dtc 51 and or 62 would have cut it off. If these codes have been set then you'll need to clear them so the ecu will allow the pump to run. Detailed inspection is needed obviously and there are other options for fluid - hope you can find a good way ahead.

 

[Tbay LX]

Ahhh, that's great, thanks so much for sending that. I'll check for codes tomorrow.

 

[colossus]

Personally I don't think the rust is that bad compared to some of the rigs I've seen up here.

 

[Moo87]

I had the same problem on my 2006 LX470 at around 105K miles, the leak was under front passenger side door. I went through the same exercise of trying to figure out why it just happen without any warning or tale-tale signs of trouble. Things I consider at the time was rust, temperature swings, recent work, AHC service and driving conditions from the previous owners, my driving history...etc. Long story short, after a month of screwing around, there was 2 facts that stand out: 1> High moisture in the fluid, positively determined by multiple test with moisture strips at multiple locations, and the accumulator joints has rust around it when I took it off. 2> There is NO record of AHC fluid change from the previous owners. This was a stock very clean accident free southern rig with about 86K miles when I got it, the guy that had it live and work in the suburbs that has light traffic and he never wheeled the rig. So, I never expect the AHC system to blowup after 20K miles, it completely surprised me. I also remember checking all the fluids before I buy the rig, and the AHC fluid was very clean and translucent, and the system worked quickly and properly. So it gave me so much confidence that all is well. Moral of the story, if I ever get another 100 rig again, I'd not just go by clean fluids and "it works good" as a sign of confidence, it must have AHC service records at proper intervals and free of rust. Otherwise I just can't pay top $ for it, because there will be an increase chance of failure that would cost me big $ down the road, especially if I plan to keep the rig awhile. I didn't know as much back then so it was definitely lesson learned. I'm sure there're people that lucked out, but there's a good reason why Toyota / Lexus put it in their books as one of their many periodic service requirements.

 

[NicaNorth]

You'll be chasing the problem for a while when dealing with the AHC system; it's pretty complex and not really a DIY project unless you have the right tools. As some members posted earlier, just replace it with conventional LC suspension. There are some good kits offered for this exact swap and it's incredibly less expensive in the long term. The AHC is a great system, but very expensive to maintain.

However, this is just an opinion, so take it as you will. This is just a suggestion.

 

[Moo87]

I had the same problem on my 2006 LX470 at around 105K miles, the leak was under front passenger side door. I went through the same exercise of trying to figure out why it just happen without any warning or tale-tale signs of trouble. Things I consider at the time was rust, temperature swings, recent work, AHC service and driving conditions from the previous owners, my driving history...etc.

Long story short, after a month of screwing around, there was 2 facts that stand out: 1> High moisture in the fluid, positively determined by multiple test with moisture strips at multiple locations, and the accumulator joints has rust around it when I took it off. 2> There is NO record of AHC fluid change from the previous owners. This was a stock very clean accident free southern rig with about 86K miles when I got it, the guy that had it live and work in the suburbs that has light traffic and he never wheeled the rig.

So, I never expect the AHC system to blowup after 20K miles, it completely surprised me. I also remember checking all the fluids before I buy the rig, and the AHC fluid was very clean and translucent, and the system worked quickly and properly. So it gave me so much confidence that all is well.


Moral of the story, if I ever get another 100 rig again, I'd not just go by clean fluids and "it works good" as a sign of confidence, it must have AHC service records at proper intervals and free of rust. Otherwise I just can't pay top $ for it, because there will be an increase chance of failure that would cost me big $ down the road, especially if I plan to keep the rig awhile.

I didn't know as much back then so it was definitely lesson learned. I'm sure there're people that lucked out, but there's a good reason why Toyota / Lexus put it in their books as one of their many periodic service requirements.

 

[Tbay LX]

Pulled the codes today, all I got was a 0dtc and a c1249 which I assume was related to the ABS light being on? Or possibly related to my issue from this thread: Headlight indicator turning on when breaking. No dtc 51 or62 like PADDO suggested. Does that mean my pump is at risk if I run it?

 

[Tbay LX]

So, if I end up going the route of replacing the AHC with stock LC shocks and springs, would that give me the same ride height as the AHC in N? I've always found the H mode sufficient for the kind of wheeling I do, plus, much higher than that and my 265 75 16 Duratracs may start to look a little bit small. If I wanted to match that height, what sort of lift would be required? I assume it's not much, since we're abel to go to high mode, and not need a diff drop.