I would make sure I have working height sensors first of all.
To help you with finding the fault(s), I'll list the most common ones.
What happens on all AHC vehicles is that :
1 - The AHC pressure becomes to high because of lack of (annual check and) adjustment of steel springs, i.e. adjustment of front torsion bars and change of rear coil springs. (Check at least every 3 years)
2 - Height sensors wear out, i.e. that the carbon trace inside the lid wears through because of normal use. (10+ years)
3 - Globes loose their pressure over time. This does not affect the height adjustment in any way though, only the ride quality and suspension travel (Which also means loss of damping and dangerous handling). (10+ years, depending on point 1)
4 - Height sensors links/arms can be damaged because of external mechanical influence, like a branch or stick bending a link arm.
Then some faults that are more frequent under influence of water and salted roads:
5 - Height sensors corrode inside, giving same symptom as a worn out sensor.
6 - Cables to sensors and valve body fail. Most commonly the small cables from sensor to fender, or the 2-3 plugs (at the left rear) between ECU and valve body.
7 - Height sensors links/arms corrode and break or ball joints get stuck and break.
8 - Leaking pressure pipes because of corrosion.
All,
I am experiencing an AHC problem, also. 2003 LX 470. Having read posts years ago, I remember the stories that say, when AHC goes, replace with (name your 4X4 suspension vendor here). The above information is really encouraging because up until the last 4 months, I loved the way my truck drove.
I did a bleeding of the suspension a few months back but it seemed there was still air in the system. So I took the truck down to the Toyota dealer and asked them to bleed the system.
After review the dealer said, "Need new rear shocks. They are leaking. $1,900." I thought about it, and if I could get the drive back for $2K what the hell, I am going to put another 250K miles on it. "Go ahead," Is said.
Hang in there the story is just getting going.
Two days later I get a call. "Ah... we drove the truck and the rear did not fix. Our fault. You need front shocks, too. Another $1,900 but it was our mistake. How about another $1,000?" I thought about it and said,"My truck back like new for $3K. Sure, go ahead and do it."
Next day, another call. "The shop foreman who has been here for 30 years is looking at your truck. He said, this repair will be $9K."
Ah... not going to spend that.
The dealership was amazing. They said, our fault. Pick your truck up, new rear AHC shocks, you don't owe us a dime for any of the work we have done. You will need to replace with standard shocks at another shop.
So then I read this thread. I have done the fluid changes on this AHC. Always with original Toyota fluid. I have never seen a leaking shock or globe in the past. So now I am thinking, I got new rears, there is some good advice above on what might really be wrong. Where should I go from here.
Other changes. I bought a replace "ride switch" in the center panel and replaced it. No change. The truck height control switch still works and the truck raises and lowers. The fluid is clear and full.
Could this be a globes problem or height sensors problem I should try and fix?
One last item, Toyota said that my pressure reading should be 7 and mine reads 4.
Sorry for the thread hijack. Any advice would be appreciated.
