AHC bottomed out on the highway (2 Viewers)

[AtoyotA]

I was just driving on the highway for 8+ hours when all of a sudden my truck started pogo-stick-ing up and down at every slight bump in the road. I thought maybe i had hit a bad stretch of road, but no other cars around me seemed to be bobbing up and down like me so i kept driving another 5 min or so until i could safely pull over.

when i got out, i saw the truck was all the way lowered - basically sitting on the wheel wells. I immediately thought i had a leaking globe, but when i checked the AHC fluid level, i saw that ALL of the fluid was in the reservoir (well above the max line). the dash said the truck was in Normal height mode so i tried raising it to H: nothing happened, i tried lowering it to L: nothing happened. I was in the middle of bfe texas on a sunday night and my heart sank. finally, maybe 10 sec after i had pressed the height adjust button, the truck raised itself back to normal operating height and everything was good and i made it home.

what tf could have caused this? a pump on the fritz that just needed a reset? i now don't feel comfortable taking my truck on road trips.

 

[suprarx7nut]

I was just driving on the highway for 8+ hours when all of a sudden my truck started pogo-stick-ing up and down at every slight bump in the road. I thought maybe i had hit a bad stretch of road, but no other cars around me seemed to be bobbing up and down like me so i kept driving another 5 min or so until i could safely pull over.

when i got out, i saw the truck was all the way lowered - basically sitting on the wheel wells. I immediately thought i had a leaking globe, but when i checked the AHC fluid level, i saw that ALL of the fluid was in the reservoir (well above the max line). the dash said the truck was in Normal height mode so i tried raising it to H: nothing happened, i tried lowering it to L: nothing happened. I was in the middle of bfe texas on a sunday night and my heart sank. finally, maybe 10 sec after i had pressed the height adjust button, the truck raised itself back to normal operating height and everything was good and i made it home.

what tf could have caused this? a pump on the fritz that just needed a reset? i now don't feel comfortable taking my truck on road trips.

My guess would be a height sensor. Get yourself techstream (just need a mini-VCI cable for OBD2 and the free software posted here on mud). The code will be stored. Alternatively, you could use one of the bluetooth scanners that reads the AHC ECU if you do not have a laptop.

The sensors are an easy replacement and a couple hundred $$. A torsion bar adjustment is free. Get yourself setup with Techstream and figure out what's going on.

 

[AtoyotA]

My guess would be a height sensor. Get yourself techstream (just need a mini-VCI cable for OBD2 and the free software posted here on mud). The code will be stored. Alternatively, you could use one of the bluetooth scanners that reads the AHC ECU if you do not have a laptop.

The sensors are an easy replacement and a couple hundred $$. A torsion bar adjustment is free. Get yourself setup with Techstream and figure out what's going on.

i was hoping you'd see this. I'll have to hook up the techstream tomorrow. about a year ago i actually followed your ahc adjustment video to a t, so thank you for that!

do you think a faulty sensor could also be the reason my truck raises and lowers the rear end whenever i'm in park?

 

[AtoyotA]

another question: do you think it was bad that i drove without any fluid in the shocks? could i have damaged other parts of the suspension going 70mph+ with the truck lowered all the way?

 

[suprarx7nut]

i was hoping you'd see this. I'll have to hook up the techstream tomorrow. about a year ago i actually followed your ahc adjustment video to a t, so thank you for that!

do you think a faulty sensor could also be the reason my truck raises and lowers the rear end whenever i'm in park?

Yes, that's sounds like bad sensor behavior.

another question: do you think it was bad that i drove without any fluid in the shocks? could i have damaged other parts of the suspension going 70mph+ with the truck lowered all the way?

There was still fluid in the shocks. Impossible to say without seeing it, but I suspect it's all fine.

 

[AtoyotA]

is there any reason to get the lexus globes over the toyota ones? (i ordered the height sensor, now kinda wanting to replace the globes).

 

[uHu]

Which height sensor did you get? Are the other two confirmed good?
There is no reason to change the globes unless the old ones are bad. First get heights and pressures right, then check globes by counting fluid use (markings on the reservoir). Then you will know the state of your globes.

 

[AtoyotA]

Which height sensor did you get? Are the other two confirmed good?
There is no reason to change the globes unless the old ones are bad. First get heights and pressures right, then check globes by counting fluid use (markings on the reservoir). Then you will know the state of your globes.

i bit the bullet and got oem for the height sensor. i actually dont know if the front sensors are good or not and tbh i dont think i have the patience to do voltage tests. i know at least one of my globes is bad based on the graduation test.

 

[AtoyotA]

and it irks me that i never had ANY issues with AHC in my '99 (and it was never serviced) but somehow i have all these issues with my '05. did toyota intentionally make the 03-05 more prone to issues or was my PO just a bad steward of this truck? these are the questions i ask myself.

 

[2001LC]

Most common cause for height sensor failure, in ordered of most common first:
1) Frozen ball joint of adjustor turnbuckle. Resulting in bending or breaking adjustor.
2) Loose nut of slide adjustor.
3) Contacts within housing.
1 & 2 are easily spotted, by looking. Have you looked?

So funny, the "Lexus" is 20% more for same part. They're the same, even the box likely the same.

 

[AtoyotA]

Most common cause for height sensor failure, in ordered of most common first:
1) Frozen ball joint of adjustor turnbuckle. Resulting in bending or breaking adjustor.
2) Loose nut of slide adjustor.
3) Contacts within housing.
1 & 2 are easily spotted, by looking. Have you looked?

So funny, the "Lexus" is 20% more for same part. They're the same, even the box likely the same.

i havent looked yet, but several months ago i did adjust the rear sensor in order to lessen the travel of the random (failed) self leveling of the rear that i mentioned earlier. the part that doesn't make sense to me is why the ahc failed while i was driving. i didn't even hit a pothole or anything - it was just 8 hours into my drive, boom i have no suspension.

so it sounds like replacing the sensor will address all of the common problems?

So funny, the "Lexus" is 20% more for same part. They're the same, even the box likely the same.

lol that's what i thought, but just wanted to make sure. i also thought that aisin parts were identical to toyota aisin parts, but it sounds like that's not the case so I didn't know what to believe! the screenshot if from impex japan - have you used them before? that globe price seems too good to be true.