AHC Problems

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M

mscott

Joined
Jul 14, 2005
Threads
7
Messages
94
Location
Raleigh, NC
Hey guys, its been a while. Ok, I'm having AHC problems on my wife's truck today. Just happened. I've done a search, and I don't find anything similar. Hopefully I'm not a guinnea pig on this one.

When I turn the wheels to the right -- moving very slowly in the cul-de-sac -- the passenger side rear wheel drops to the bump stop. You can feel it hit. When I turn the wheels to the left -- same conditions -- the drivers side rear wheel raises all the way to its highest extension.

The truck is VERY difficult to move, and I am afraid there could be diff/tranny issues if I try to power through.

Then when normal speed -- 15+ -- everything is fine.

HELP!!!! My wallet is panicking right about now. Any ideas?

-- Mike
 
My only idea is to check how level the cul-de-sac is, and to try it in a different place, like a mall parking lot, same angle on the wheels.

I know that LX's (not sure about LC's with AHC) have an auto-leveling feature. If you're doing this Left turn with your front right wheel in the gutter (given, it would have to be fairly deep gutter), and because the rearwheels don't track exactly like the front, the rear right wheel would be slightly out of the gutter, the auto-level would try to extend the front right, and lower the left rear in order to keep the body of the truck as level as possible.

I could be completely wrong about this, but that seems like it could be the reason.


Truck is very difficult to move? At any time, or only when the wheels are turned to the lock? - Is the CDL engaged?

Thoughts?

-LX Pilot
 
Pilot,

Unfortunately not. The cul-de-sac is level, and I've driven out of my driveway thousands of times. This is an extreme situation and repeatable anywhere driving slowly and turning the wheels. Low is right on the bump stop, high is as high as it will extend up. It looks and feels like a carnival ride.

At least I know my actuators are working fine...
 
Strange indeed...
You say turning the wheels... Do you have to turn the wheels all the way? Or is a 30 deg turn of the steering wheel enough? (there is a sensor for that)
Also, do you get the same behavior when stationary with engine running, or do you have to be moving?

I would say you need to pull some codes. (Some codes can be "read" via different lights on the dash, if you put it in diagnostics mode. But you would need the FSM for that, rather lenghty procedure)

Could be water/corrosion or something loose, like a connector.
 
Not saying I would try this without further corroboration, but my insurance guy has an IS and said that by shorting the first and last terminals of the OBDII connector under the dash, some light in the cluster will start a flashing sequence - the number of flashes indicates the number - 3flashes 8flashes 2flashes = 382

The meaning of the code must be deciphered - most of them are available here:http://autorepair.about.com/cs/troubleshooting/l/bl_obd_main.htm

Personally, I'd put down the $80-some-odd bucks for a reader - nevermind not wanting to damage the diagnostic system, I don't have the patience to sit while it flashes a 4digit number at me - I'd lose track and come up with the wrong code.

-LX Pilot
 
I'm wondering if it would even be throwing codes, since there is no idiot light or any indication that the truck thinks there is something wrong?
 
As I understand things (which is not very well a vast majority of the time ;) ) Codes are generated all the time, and not all of them are tied to an indicator - or they'll be tied to a general indicator such as "Check Engine".

-LX Pilot
 
yesterday i saw a 03+ LX470 with MAJOR AHC problems. Haha was so funny looking. This lady was driving her white LX down Route 1, with basicly....the front SLAMMED and the back fully jacked up. Looked agressive! But i hope she realizes her truck needs servicing.

I have seen another woman once, a sand dollar LX470, with the FRONT fully jacked up on the AHC and the rear sagging....that thing just looked funny. I pulled up next to her and checked in the cargo area...empty!


Anyways, maybe your problem is somewhat similar to theirs, just yours goes diagonal across the car, and theirs are front/rear problems. Ied highly suggest you bring it to a lexus dealership for inspection of the system, as your problem could actually be dangerous if it were to happen in certain situtations.
 
Maybe just unhook the battery and try to reset everything and see if you would have the same problem, good luck!
 
I just picked up a 2003 LX for the wife and kids last week, 35K, all services from Lexus, CPO blah...blah...blah...

After two days of driving it felt like the suspension was a little soft, even in sport , in the morning the front end would be really low and pop up when she started it - so I asked lexus to check it out.

It turns out they replaced accumulators/shocks on all four corners.

Don't know if this was a big job not.

My guess is you may have one or more bad accumulators, altering front end geometry, and causing your Tcase to bind in turns.

Your sure your diffs are not locked...right...?
 
Had a Ride Height Sensor issue on the LX - had the slammed look 1LoudLX saw. Took it in they replaced all and no issues since. Seems the RHS are somewhat trouble prone (theres a TSB on them). Seems odd only one side is effected in a turn - could be RHS could be as lancaster points out . Take it in before you end up slammed and get laughed at as well.

RHS thread
https://forum.ih8mud.com/showthread.php?t=90170
 
There is a woman I see on the way to work, almost everyday, in a 2006 LX. The front of hers sits way up in the air, and the back looks normal. I saw her at a gas station one day and try to explain that she might want to have her car serviced. She looked at me like I was a serial killer and reached in her pocket book. When I concluded that she was probably reach for a can of mace, I told her to have a nice day and got the h*ll out of there. She be replacing CV joints in about a year.
 
hkeller said:
There is a woman I see on the way to work, almost everyday, in a 2006 LX. The front of hers sits way up in the air, and the back looks normal. I saw her at a gas station one day and try to explain that she might want to have her car serviced. She looked at me like I was a serial killer and reached in her pocket book. When I concluded that she was probably reach for a can of mace, I told her to have a nice day and got the h*ll out of there. She be replacing CV joints in about a year.
Click to expand...

People like this go around blissfully ignorant. Nevermind the fact that due to the nose up attitude, she is probably blinding everybody at night from her mis-aimed headlights. At least you tried to do the right thing.
 
lancaster said:
I just picked up a 2003 LX for the wife and kids last week, 35K, all services from Lexus, CPO blah...blah...blah...

After two days of driving it felt like the suspension was a little soft, even in sport , in the morning the front end would be really low and pop up when she started it - so I asked lexus to check it out.

It turns out they replaced accumulators/shocks on all four corners.

Don't know if this was a big job not.

My guess is you may have one or more bad accumulators, altering front end geometry, and causing your Tcase to bind in turns.

Your sure your diffs are not locked...right...?
Click to expand...

Prev. owner probably put the wrong fluid in the resevoir. That seems to be the only thing that kills the four accumulators (globes) with near certainty. AHC fluid isn't spec'd to be flushed until 60K mi. There are a series of diagnostic tests you can perform for the height (IIRC, you have to short out a couple of pins in the box behind the DRL relay and put the ride quality switch in a certain mode, then you can adjust each corner of the vehicle in 1/16 increments. You need vol 1 of the FSM. It's explained in great detail. I'm sure a tech w/ lexus tester can find the culprit in a fraction of the time as you can.
 
lancaster said:
So would have they replaced all the fluid along with the globes?
Click to expand...

I think so, as one can (2 liters) is enough to flush the 4corners (I think you need 2 cans if you want to flush the height actuator too). You have to bleed each damping accumulator after reinstalling the globe to get the air out of the system, and if you're familiar with the process, when you open the bleeder valve, the vehicle will drop to the bumpstop at that corner. The only place where there might be old fluid stuck in the system is the height actuator (the cylindrical shaped thing under the driver's side running board). When I had my dealer flush my AHC last summer, I specifically told them to do all 5 bleeder plugs. The service manager tried to give me some bull about there being air in there, so it was un-bleedable. I insisted it could be done according to the factory manual, and a tech standing nearby said it could be, although they ususally just do the globes. This just shows that whenever you have service done, make sure you know exactly what's being done and have the service manager write it on the form for the tech.
 
There would be old fluid in the shocks as well (although, from experience, the shocks seem to be ok with brake fluid for a while). And in the pipes between the actuators and the shocks. To get ALL old fluid out, you would have to take off the shocks and flush them, in addition to emptying the accumulator and flushing (bleeding) the whole system.
That being said, it doesn't sound like this is Mike's problem here. If the "globes" were shot from bad fluid, the symptom would be "no suspension", meaning a hard ride.
 
Well I have an update. It turned out to be the CDL. Apparently it was engaged without any indicator lights. So, the good news is that it just cost me $84 for diagnosis and remedy. Too bad I didn't mess with it myself to try to dis-engage it as I thought about that as a cause. Glad my wife wasn't driving it because she probably would have ripped it right out of the bottom of the truck. Now we need to have another converstaion about "that one button that you NEVER touch".

So what I was experiencing was the body being torqued aroung the axle as the wheels we trying to move at different speeds. Since the diff was locked, it was just binding up on the smooth pavement and causing the body to roll.

This story ends well enough, now I just need to determine why there was no indication it was locked...

Thanks for all the input.
 
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