AHC debug... won't go HI (1 Viewer)

[TexFJ]

Just purchased my LX470 so bear with me.

My AHC will go down from N position to LOW. But it never comes up to N if requested through the UP button.
Once I start driving, it will go from LOW to N, as it should.
It will not go into HI from N... It will not go into N from Low.

Is my button UP button broken or is there a different possibility?

 

[Ramathorn15]

Just purchased my LX470 so bear with me.

My AHC will go down from N position to LOW. But it never comes up to N if requested through the UP button.
Once I start driving, it will go from LOW to N, as it should.
It will not go into HI from N... It will not go into N from Low.

Is my button UP button broken or is there a different possibility?

Does the green light flash on H for a couple seconds after you hit the button? Sounds like a classic over pressure scenario. You likely just need to get techstream hooked up, figure out your neutral pressures, then adjust the torsion bars and/or add rear spring spacers or new springs.

 

[TexFJ]

When it doesn't work, the light doesn't flash at all. Doesn't even look like it's trying. Either the button is messed up or the computer doesn't think it should be allowed to go there.

 

[riffman12]

just ruling out simple things here, are all your doors closed when you hit the up button?

 

[suprarx7nut]

When it doesn't work, the light doesn't flash at all. Doesn't even look like it's trying. Either the button is messed up or the computer doesn't think it should be allowed to go there.

Step one for any new AHC-vehicle buyer is to get a laptop that will run techstream. It can be a $50 10 year old PC off ebay or craigslist.

You need to measure neutral pressures and adjust the torsion bars to get reasonable pressures up front. That's probably 95% of the pain when dealing with AHC. The solution is super simple and often completely free.

 

[TexFJ]

just ruling out simple things here, are all your doors closed when you hit the up button?

Ha... I did try it one time and even LOW wouldn't work... until I closed my door
Unfortunately the doors were closed when I tried up.

 

[TexFJ]

Step one for any new AHC-vehicle buyer is to get a laptop that will run techstream. It can be a $50 10 year old PC off ebay or craigslist.

You need to measure neutral pressures and adjust the torsion bars to get reasonable pressures up front. That's probably 95% of the pain when dealing with AHC. The solution is super simple and often completely free.

Thanks for the tip. Do you know if Foxwell reader can do similar things? I'm assuming I would have to update my firmware on the NT510. Actually I never did get a response from Foxwell, seems like their customer service sucks. I'll just get the OBD USB cable and just get TechStream.

 

[TexFJ]

Here is a short video of the problem. Unsuccessfully tried HI twice then pushed LOW. For some reason it doesn't go into LOW until I start to drive slowly... hmmm

 

[TexFJ]

Step one for any new AHC-vehicle buyer is to get a laptop that will run techstream. It can be a $50 10 year old PC off ebay or craigslist.

You need to measure neutral pressures and adjust the torsion bars to get reasonable pressures up front. That's probably 95% of the pain when dealing with AHC. The solution is super simple and often completely free.

Anyone know a cheaper way to get TechStream?

 

[suprarx7nut]

Thanks for the tip. Do you know if Foxwell reader can do similar things? I'm assuming I would have to update my firmware on the NT510. Actually I never did get a response from Foxwell, seems like their customer service sucks. I'll just get the OBD USB cable and just get TechStream.

No idea what that is, but my guess is a confident no. Techstream is proprietary Toyota stuff.

Anyone know a cheaper way to get TechStream?
View attachment 2311242

Google "Techstream in 5 minutes" . Someone in here packaged it all up nice and tidy. All you need is a $35 cable and a laptop.

That $1500 getup is for professional techs. Not a diy dude.

 

[TexFJ]

No idea what that is, but my guess is a confident no. Techstream is proprietary Toyota stuff.



Google "Techstream in 5 minutes" . Someone in here packaged it all up nice and tidy. All you need is a $35 cable and a laptop.

That $1500 getup is for professional techs. Not a diy dude.

I'm a professional DIY'er.

BTW, I've heard there is an FSM with AHC. I have the 04 version but doesn't go into AHC.

 

[suprarx7nut]

I'm a professional DIY'er.

BTW, I've heard there is an FSM with AHC. I have the 04 version but doesn't go into AHC.

You and me both! But if you're not running a few grand a day through a shop, that $1500 Techstream isn't meant for you.

For the fsm, yes, there's a version specifically made for each model for each year. Any model/year combo that had AHC will have that in the manual.

The manual set is around 5,000 pages for the later year LX.

 

[TexFJ]

You and me both! But if you're not running a few grand a day through a shop, that $1500 Techstream isn't meant for you.

For the fsm, yes, there's a version specifically made for each model for each year. Any model/year combo that had AHC will have that in the manual.

The manual set is around 5,000 pages for the later year LX.

View attachment 2311319

That's a lot of trees there. PDFs are better

 

[TexFJ]

Got the TechStream up and running.

Unfortunately I can't get pressure readings and I'm getting a code C1762 ( abnormal oil pressure for Pump). BUT the semi-good news is that the UP button on the AHC control is not working as it should. TS recognizes my down button but not my up button.

So, I'll be debugging the switch and the error code. Someone on MUD had some air in the system and it fixed the code.

 

[planomateo]

Got the TechStream up and running.

Unfortunately I can't get pressure readings and I'm getting a code C1762 ( abnormal oil pressure for Pump). BUT the semi-good news is that the UP button on the AHC control is not working as it should. TS recognizes my down button but not my up button.

So, I'll be debugging the switch and the error code. Someone on MUD had some air in the system and it fixed the code.

Make sure you're selecting Lexus LX470. It will default to a 00 Land Cruiser.

 

[TexFJ]

AHC dataset does show up so it should confirm my setting of LX470. I’m guessing this dataset wouldn’t show up for LC’00 default config.

one thing I’ll try is to clear the code as perhaps it came on because I had the front end up changing the wheel bearings and rotors. During this time the height sensor LED showed “HI” on the dash so I guess that’s working.

 

[ticoman]

In your video, you are in drive .Do you have your foot on the brake? AHC will not engage if you have a brake,or E brake, or door or back hatch open. Have you read Definitive list of AHC maintenance items in it's entirety?.....Twice?

 

[TexFJ]

In your video, you are in drive .Do you have your foot on the brake? AHC will not engage if you have a brake,or E brake, or door or back hatch open. Have you read Definitive list of AHC maintenance items in it's entirety?.....Twice?

Interesting. Wasn't aware that hand brake caused the AHC not to engage. Unfortunately I just had my foot on the brake in the video and the hand brake wasn't engage (light wasn't ON the dash), and the N to Low was successful, just not the other way.

It'll probably rain today and keep me away from the lake so I'll read the Definitive list of AHC maintenance items instead

 

[suprarx7nut]

Interesting. Wasn't aware that hand brake caused the AHC not to engage. Unfortunately I just had my foot on the brake in the video and the hand brake wasn't engage (light wasn't ON the dash), and the N to Low was successful, just not the other way.

It'll probably rain today and keep me away from the lake so I'll read the Definitive list of AHC maintenance items instead

If the brake is on, AHC is supposed to not move heights. To move heights, put it in park, foot off brake. Hand brake should be ok.

If the car isn't totally on the ground, ahc isn't going to work and you should not cycle heights. If you're doing any other work on it and a wheel is in the air, wait until you've got it all back on the ground to troubleshoot ahc.

 

[suprarx7nut]

That's a lot of trees there. PDFs are better

If you can find your year and model that's fine. I could never find a PDF other than the one jumbled 2004 version.