AHC trouble, bouncy rear end (1 Viewer)

[grumblefish]

I've got an '01 LX with about 230k. I've had it for about 2 years now, second owner, and the original maintenance history is impeccable. The AHC has worked as intended, until yesterday. We flushed the fluid last summer, because we weren't sure when it was last done. Last night I noticed that the rear end was super bouncy, even over the smallest bump. When I got home I tried cycling the system, and only the front end adjusts. In the light of day, I can see now that she's sitting super low in the rear. Fluid reservoir is full and there is no evidence of leaks. I've been searching the forum trying to get an idea of whether this might be a globe/accumulator issue or of it might just be a height sensor issue, but am coming up blank. We do not have a techstream. I do like the AHC, but if I'm going to spend $$$ repairing it, I'd almost rather just delete and spend the money on a small lift. Is there much if anything that we can figure out without a techstream?

 

[GTV]

Nope. Techstream cable is about $30. It’s a small investment and it will do a whole lot more than just read your AHC pressures. Anything else is just guesswork.

 

[grumblefish]

Nope. Techstream cable is about $30. It’s a small investment and it will do a whole lot more than just read your AHC pressures. Anything else is just guesswork.

As I suspected. For some reason I thought techstream was significantly more expensive and was pleasantly surprised when I started looking at them this morning.

 

[suprarx7nut]

As I suspected. For some reason I thought techstream was significantly more expensive and was pleasantly surprised when I started looking at them this morning.

Yup, the hardest part of getting started with AHC work is setting up Techstream. Once you get over that hurdle, it's not too bad.

You're probably just over-pressure or have a bad height sensor. Techstream will likely reveal the answer in 30 seconds once you get it going.

Keep in mind that there are essentially no AHC failures that cost anywhere near as much as you might have heard. Insane/unethical/misguided dealer quotes have created a false impression that AHC is ungodly expensive to maintain or repair. It's a baseless idea when you consider current parts availability and community knowledge. Globes are a wear item and cost ~$750 every decade or so. New springs or spacers are a couple hundred at most. The shocks almost never require replacement. The pump is $250. Unless you have catastrophic rust that's ravaging your undercarriage, there's no normal failure of AHC that would be as expensive as even a cheap lift kit.

We can walk you through the journey.

Check out this if you haven't already.

AHC Info

Note: AHC services are now offered at the Air Down Gear Up shop in Frederick, CO. The owner of YotaMD, Andy, is also a co-owner of ADGU and happy to provide some of the common AHC-related tasks you may be interested in. See the link here for details...

www.yotamd.com

 

[nukegoat]

On the plus side your rigs new nickname can be "mr twerky pants"

 

[hoser]

As I suspected. For some reason I thought techstream was significantly more expensive and was pleasantly surprised when I started looking at them this morning.

Techstream is indeed significantly more expensive. For $30, you're buying "Tekstreem" in an unmarked package.

 

[grumblefish]

On the plus side your rigs new nickname can be "mr twerky pants"

Mr Twerky pants.

 

[grumblefish]

Yup, the hardest part of getting started with AHC work is setting up Techstream. Once you get over that hurdle, it's not too bad.

You're probably just over-pressure or have a bad height sensor. Techstream will likely reveal the answer in 30 seconds once you get it going.

Keep in mind that there are essentially no AHC failures that cost anywhere near as much as you might have heard. Insane/unethical/misguided dealer quotes have created a false impression that AHC is ungodly expensive to maintain or repair. It's a baseless idea when you consider current parts availability and community knowledge. Globes are a wear item and cost ~$750 every decade or so. New springs or spacers are a couple hundred at most. The shocks almost never require replacement. The pump is $250. Unless you have catastrophic rust that's ravaging your undercarriage, there's no normal failure of AHC that would be as expensive as even a cheap lift kit.

We can walk you through the journey.

Check out this if you haven't already.

AHC Info

Note: AHC services are now offered at the Air Down Gear Up shop in Frederick, CO. The owner of YotaMD, Andy, is also a co-owner of ADGU and happy to provide some of the common AHC-related tasks you may be interested in. See the link here for details...

www.yotamd.com

Awesome. Thanks for the link!

 

[Stuzu]

I would check the rear height sensor and/or replace. Maybe post a picture or two.

 

[loop737]

Rear height sensor, had the same issue, swapped it out, now good as new. You can get an Aisin unit on rock auto relatively cheap.

 

[TMack66]

Hi guys. I hope you don't mind me jumping into this thread. I have a 98 470. 355K miles. I love this truck. Having problems with a really bouncy ride. I've flushed and replaced the fluid. Saw a lot of air in the fluid when doing that. Took a while to remove it. The new fluid didn't do anything - other than let me know it's not a fluid issue. I've never replaced anything on the AHC. I purchased a Techstream cable. It also came with a Techstream installation CD. Techstream appears to need dealer registration codes, etc. to properly install. I don't have any of that. Do you recommend I take the time to figure out how to get Techstream up and running or should I simply take the step to replace the globes as I'm sure they're at the end of their life or very close. ? Could really use your guidance. I'd like to keep the AHC as it's been so good for so long.

 

[TMack66]

Hi guys. I hope you don't mind me jumping into this thread. I have a 98 470. 355K miles. I love this truck. Having problems with a really bouncy ride. I've flushed and replaced the fluid. Saw a lot of air in the fluid when doing that. Took a while to remove it. The new fluid didn't do anything - other than let me know it's not a fluid issue. I've never replaced anything on the AHC. I purchased a Techstream cable. It also came with a Techstream installation CD. Techstream appears to need dealer registration codes, etc. to properly install. I don't have any of that. Do you recommend I take the time to figure out how to get Techstream up and running or should I simply take the step to replace the globes as I'm sure they're at the end of their life or very close. ? Could really use your guidance. I'd like to keep the AHC as it's been so good for so long.

I fogot to mention that I only have 4-5 graduation levels change between high and low.

 

[YotaWagon]

I fogot to mention that I only have 4-5 graduation levels change between high and low.

7 graduations is considered end of life.

 

[TMack66]

7 graduations is considered end of life.

So I should start by replacing the globes?

 

[grumblefish]

Hi guys. I hope you don't mind me jumping into this thread. I have a 98 470. 355K miles. I love this truck. Having problems with a really bouncy ride. I've flushed and replaced the fluid. Saw a lot of air in the fluid when doing that. Took a while to remove it. The new fluid didn't do anything - other than let me know it's not a fluid issue. I've never replaced anything on the AHC. I purchased a Techstream cable. It also came with a Techstream installation CD. Techstream appears to need dealer registration codes, etc. to properly install. I don't have any of that. Do you recommend I take the time to figure out how to get Techstream up and running or should I simply take the step to replace the globes as I'm sure they're at the end of their life or very close. ? Could really use your guidance. I'd like to keep the AHC as it's been so good for so long.

I ordered a cable that came with a disc. It just came today and I started installing it on an old laptop. Buried in the files were instructions and the registration code was in there. Maybe check the text files on your disc.

 

[trdcorolla]

So I should start by replacing the globes?

AHC graduations are only valid if the pressure is in spec, get TS working and go from there.

 

[TMack66]

What is TS?

 

[TMack66]

What is TS?

BTW - I should add that the system appears to move somewhat properly from L to N to H, although there is an odd knocking sound (hard to describe) coming from both the front left and front right when I go from L to N. No blinking lights on AHC indicator and vehicle raises/lowers in accordance with the AHC switch. However, there is still only a 4-5 graduation change

 

[TMack66]

What is TS?

Just figured it out TS is Techstream. Thanks.

 

[grumblefish]

Update- sensors and accumulators are all in working order. The bracket that holds the rear height sensor in place broke and the sensor is just hanging. We figured this out after we got the techstream up and running and the rear sensor value was out of whack. The good news here, besides no catastrophic failure, is that I now have a techstream to make sure we get the sensor back in the right position and that my husband finally had an excuse to buy a welder.