lx470 AHC dropping / moving while driving (1 Viewer)

[saxman2u]

The lx470 ahc is moving while driving. I can't tell if it is moving up or higher when driving, but I can definitely tell when the truck is lowered or goes down while driving and then remains in a lowered position. It feels like the front of the vehicle is being lowered, but not 100% sure. Happens at any speed. 2001, 210K miles. No problems with the AHC before this at all and no lights are on on the dash. All original parts on the suspension and the truck rides nicely. Thoughts or ideas of where to start or what should be replaced/checked? This problem is intermittent and most of the time the truck drives fine.

Thanks for any input.

 

[2001LC]

Fluid level is first place to start looking.

 

[LXG8R]

Leveling while driving is normal. Mine did it more often before I read the AHC pressures and cranked the t-bar and added spacers to the springs.
I had mine go into low on a trip where I had accidentally locked the center diff without knowing it. I guess the LX tries to raise when its locked and mine just gave up. Stoping, unlocking it, and letting the pump cool down while we ate cured it.

 

[saxman2u]

Thanks for the input. Forgot to mention we are the original owners. The leveling down does seem odd and this seems like something new and out of the ordinary. Will report back after checking fluid.

 

[2001LC]

Condition of fluid is import to health of pump and seals. I'd have flushed fluid 3 or 4 times by 210K miles.

 

[saxman2u]

So, finally had time to flush and replace the fluid. The fluid was nasty, it has been a long time, well over 100K. While in park, the rig responds correctly when I select the "H" and the "L" for the AHC. However, while driving again the other day, in the midst of a 20 mile trip and going 55 MPH, I can see the front the truck dive down quite a bit. I never remember it doing this in all of the years we have had the truck. Fluid level is good, maybe a little overfilled. Not sure where to start? Thanks for any input.

 

[J1000]

A good place to start is getting Techstream working and reading the hydraulic pressures in the system and making sure they are within spec. Does the AHC indicator show L on the dashboard when you feel the front end drop or does it stay in N?

 

[saxman2u]

ok, is there a writeup on techstream or any info you can send.

As for the height, the green indicator light remains on "N" when the lowering in the front happens on the highway.

 

[bpe3]

I’ve had the same problem with my 2001 LX since I bought it at 158k miles. Now at 227k miles. I don’t notice it when driving, but from time to time at a red light I notice it raise or lower. It happens sometimes with the shifter in park too. The light on the dash doesn’t change. Just random up or down. When I use the button to raise or lower, it seems to always work fine. I’ve changed the AHC fluid twice. Fluid level is fine.

There’s always something of higher priority else that needs fixing, so I’ve just lived with it. Random Guess: height sensors.

 

[repsforjesus315]

I’ve had the same problem with my 2001 LX since I bought it at 158k miles. Now at 227k miles. I don’t notice it when driving, but from time to time at a red light I notice it raise or lower. It happens sometimes with the shifter in park too. The light on the dash doesn’t change. Just random up or down. When I use the button to raise or lower, it seems to always work fine. I’ve changed the AHC fluid twice. Fluid level is fine.

There’s always something of higher priority else that needs fixing, so I’ve just lived with it. Random Guess: height sensors.

Hey! Did you ever get around to figuring out why your lx does this? I’m having the same issue and am looking for answers.

 

[saxman2u]

It finally resolved itself on its own. I changed the fluid, it had not been done in a while, and the problem got better. My wife drives it more than me, but when I drive it now, i do not notice it. Change your fluids and wait a few months.

 

[777300er]

For anyone reading in the future, check your neutral pressures. I'd bet his are quite high up front.

 

[2001LC]

That is certainly one reason. For one: High pressure fluid gets to hot. Shut down system until cools.

 

[JohnVee]

I don’t notice it when driving, but from time to time at a red light I notice it raise or lower. It happens sometimes with the shifter in park too. The light on the dash doesn’t change. Just random up or down.

Exactly the same for me. I'd say well over 90% of the occurrences happen while stopped, and the rest while steadily moving slowly in traffic (under 15mph).

For anyone reading in the future, check your neutral pressures. I'd bet his are quite high up front.

That is certainly one reason. For one: High pressure fluid gets to hot. Shut down system until cools.

Not disagreeing with either of you, and I couldn't anyway since I've not checked my pressures, but it's a year 'round issue on my truck going between South Carolina and DC, though it can go weeks without happening, and is by far most common in the first 1-10 miles of city traffic no matter the air temps. Maybe there's a buildup of pressure upon startup that dissipates after a while? I never really gave the matter much thought until I saw this thread today. Reminds me that I've got some AHC fluid waiting on me at the house!