Ditching the AHC

[hickok]

Well I'm at a point where I either need to dump a bunch of funds into relpacing the pump on the AHC and other gadgets or just flat out ditch the AHC all together. I have had problems with the AHC since I've owned the truck and would prefer a less complicated system....back to the basics suspension.

Has anyone replaced the AHC system with Slee's system or OME?

Any imput would be appreciated.

 

[tabraha]

If they have I don't believe it's been posted about. Make sure you give us the details! I'd call Christo and talk to him about it too.

 

[uHu]

Interesting Project.
Would for sure like to know what has to be changed to get rid of AHC. Only know of 4x springs and 4x shocks.
You could find 2nd hand parts if you want to keep AHC.
Anyhow, what problems did you have?

 

[sleeoffroad]

Jimmy, on a 98/98 LX470 I think there is no problem to remove the parts and replace with OME. However on the later ones I have to check if there is a coupling between the suspension and the stability control systems.

There are a lot of imputs to the AHC, but I do npt believe it gives feedback to any of the systems. A look at the wiring diagrams might be helpfull.

 

[hickok]

Thanks for the info guys. Swapping out for OME parts seems to be cheaper and reliable way to go.

uHu - Last week I was in Florida traveling from Indialantic to Orlando and about half way to Orlando, the front suspension dropped to the "L" mode and stayed there. I checked all fuses, relays and height adjustments to see if anything was off. The front driver's side height adjustment was off by about 1/2", so re-adjusted it to the passenger side level. Nothing changed.

I disconnected the battery thinking maybe something needs to reset, nothing. I was able to manually set the relay with a screwdriver and I could hear the pump slowly trying to push fluid and then the pump would stop. The pump was making a moaning sound and when I placed a test light to it, there was a very low current powering the pump. Not sure of the voltage but the test light was very dim.

Also in the past, if I'm traveling at 70mph consistently for over an hour, the suspension automatically sets itself to the "firm" position and overrides all button or functions on the dash. I have to pull over, turn the vehicle off and then restart to "reset" the system back to normal.

 

[Tinkerer]

Let us know how it goes.

I had a similar highway "default to firm" experience, but only at one particular stretch of highway, near Anniston AL: The concrete pavement slab joints are severe, causing rapid high-magnitude (high-travel) suspension jounce, with very regular period.

After a several minutes of this, it would cause the "full firm mode, have a nice day". Reset by shutting off the engine, then restarting. (Rebooting)

I believe the system sensor inputs to the computer simply overloaded the computer and/or memory, causing the classic "stack overflow" crash, cauing the computer to then go into a limp mode.

Happened a few times, at that one location, but it never did it anywhere else.

 

[hickok]

I will let you know the progress. Looks like I'll be swapping out with OME. Easier, less expensive and more reliable than the AHC.


....although I do like the auto level with the Lexus system.

 

[hickok]

I also want to install a 2" body lift after the suspension for 37". So after my swap, I'll have a set of 315/75 r 16's Nitto Terra Grapplers for sale with about 5000 miles on 'em.

 

[hoser]

Keep in mind if you go 37's:

You won't be able to fit "off the shelf" bumpers and sliders.
You won't be able to fit a spare tire in the stock location, if desired.
You'll want to choose a narrow 37... something like 37x11.5-16
The required amount of brake pedal pressure has gone up signifcantly with 35's, It will go up even more with 37's.
You will need to regear to 5.29's

With that being said--go for it! I'd love to see bigger tires on a 100.

 

[Tinkerer]

....although I do like the auto level with the Lexus system.

Ya, discovered that this is actually useful, especially when towing...

But the KISS principle carries its own allure, too...

 

[SINCITY100]

Keep in mind if you go 37's:

You won't be able to fit "off the shelf" bumpers and sliders.
You won't be able to fit a spare tire in the stock location, if desired.
You'll want to choose a narrow 37... something like 37x11.5-16
The required amount of brake pedal pressure has gone up signifcantly with 35's, It will go up even more with 37's.
You will need to regear to 5.29's

With that being said--go for it! I'd love to see bigger tires on a 100.

Do you think ya` scared him Hoser ? !

37`s ?.. good lord !!

 

[tabraha]

40's!!!!! ;p

The quest for big tires never ends!!!

 

[greenflash]

Hi all-
Looks like I'm in the same boat as James (hickok): I'm seriously considering the Slee OME 2" lift upgrade/diff drop on a 1999 LX 470. (My OEM shocks failed at 105K miles, and the dealer wants $1700 to replace them!?)

The only downside seems to be losing the AHC functionality. But I'm wondering what happens with the AHC system (disconnected/removed)? I'm going to have a local independent toyo/4x4 shop do this- perhaps it will be apparent? Just looking for any definitive advice... Thanks in advance!

Daniel

 

[uHu]

I will let you know the progress. Looks like I'll be swapping out with OME. Easier, less expensive and more reliable than the AHC.
....although I do like the auto level with the Lexus system.

Hickok,
Any news? How did it go with your suspension? Did you ditch the AHC? Any issues with going OME?
Just thinking what to do when the next AHC problem hits me.

 

[uHu]

Hi all-
Looks like I'm in the same boat as James (hickok): I'm seriously considering the Slee OME 2" lift upgrade/diff drop on a 1999 LX 470. (My OEM shocks failed at 105K miles, and the dealer wants $1700 to replace them!?)

The only downside seems to be losing the AHC functionality. But I'm wondering what happens with the AHC system (disconnected/removed)? I'm going to have a local independent toyo/4x4 shop do this- perhaps it will be apparent? Just looking for any definitive advice... Thanks in advance!

Daniel

Is it really the shocks themselves that have failed?
Heard somewhere (maybe on some forum) that they can be serviced. Change some rings, as the shock function (dampening effect) is really in the actuators next to the gas spheres.

 

[Jim_Chow]

Aren't the AHC shocks only like $200 a piece?

 

[DMX84]

Also the torsion bars will need to be replaced. The LX uses a softer t-bar.

 

[Jim_Chow]

I checked the AHC connections in the 03 FSM electrical manual last night. I believe you can unplug the AHC ECU, but there are 2 inputs from the VGRS (tells you how many rotations of the steering wheel you've made), plus 2 inputs from the ABS/TRAC ECU (wheel speed). These are used by the AHC to increase roll resistance for stuff like when cornering, etc. Those outputs might expect to be connected to something. Since you have a 98, VGRS isn't a factor, leaving the wheel speed sensor inputs. That's the only show-stopper I could find.

 

[siglo]

I've just removed the AHC shocks.. I'm mainly experimenting, nothing was wrong with the system.. My LC is 2004 and has no TRAC etc AFAIK.. What I've had them do is bleed the system, disconnect the fuse, disconnect the pump and remove the shocks.. I have OME133 shocks in the front and 101s in the rear now.. OME t-bar is still there and I've replaced the OME860 coils with OME863s.. I'm still having problems, the rear is low now as the OME863 are not enough so I ordered 864s.. I can't crank up the font end because the bolts are stuck.. there seems to be some room still to tighten them though.. I'm having the t-bars removed and everything cleaned then I will try again..

If I like the OME setup, I will go ahead and remove the rest of the AHC components.. Any input will be greatly appreciated

 

[Greg B]

I'm still having problems, the rear is low now as the OME863 are not enough so I ordered 864s.. .. Any input will be greatly appreciated

Wow! The 863's are not enough? You must have some serious weight in that 100. I have 863's too, and I can't get them to drop at all. I know, from previous posts, you have an aftermarket rear bumper and cargo drawers. What else do you have in the back? I'm curious to know how much weight it takes to over-power the 863's.

As far as input on ditching the AHC, I doubt you'll get much. As far as I know, you are the first person that has done this. So consider yourself an AHC pioneer. Good luck to you, I hope all goes well with the conversion.