The Dreaded AHC ...

[mwk]

Bought a used 2006 LC with AHC. Lemon Squad inspected and stated that the ahc was working but oil was low....
Well I got to Ohio, and it wasn't working...judging by the inspectors pics of the low oil reservoir(max is 1/3 from the bottom, btw) and the AHC LO led lit up...he clearly thought the led was an oil level indicator, rather than a positional one...
Fast forward to today...Dealer says its all these codes and you need an accumulator solenoid assy...



Nearly all have said once you start chasing this system, just go to a standard suspension and take AHC out.

CarSpec, John was fantastic btw, thought i ought to get one more opinion from an independent toyota centric shop...but in the end felt I was destined to remove the AHC.

Cruiser parts has a good price on the non ahc springs and shocks...no torsion bars.

Soooooo

My questions are:

1. Do I HAVE to change the torsion bars, or does the "AHC torsion bars are not up to the post AHC job "argument hold
2. Any downside to putting in the more affordable OME torsion bars with the Toyota OEM shocks and springs?
3. MUST i drop the diff in the above situation if it will only leave it at approximately the AHC Neutral height?
4. Do I need another opinion? I do not want to chew up good money on diagnostic hours

THX
MWK

 

[sdnative]

What are your plans for the truck?

If you just plan on leaving it stock, I would use non-AHC OEM components (new shocks, and either new or low mileage used springs/TB). From what I understand OME torsion bars ride harsh without a lot of weight. I still have the OEM on mine with a good amount of weight and the ride is fine.

If you are modifying the truck, well then it depends.

 

[mwk]

What are your plans for the truck?

If you just plan on leaving it stock, I would use non-AHC OEM components (new shocks, and either new or low mileage used springs/TB). From what I understand OME torsion bars ride harsh without a lot of weight. I still have the OEM on mine with a good amount of weight and the ride is fine.

If you are modifying the truck, well then it depends.

Thx mate so you would change the ach tb to non ach Toyota tab?

 

[mwk]

Thx mate so you would change the ach tb to non ach Toyota tab?

Yes stock

 

[mwk]

What are your plans for the truck?

If you just plan on leaving it stock, I would use non-AHC OEM components (new shocks, and either new or low mileage used springs/TB). From what I understand OME torsion bars ride harsh without a lot of weight. I still have the OEM on mine with a good amount of weight and the ride is fine.

If you are modifying the truck, well then it depends.

Sd. Do you recommend bailing out on the ahc?

 

[mgoblue]

I had AHC on my first 06, and I have it on my current one. I love the system, and have always taken care of it in both trucks (flushes, adjusted TB's etc) but as seen as it shows the first sign of going south (i.e. any of the components needing to be replaced) it's all coming out for a traditional setup. I would get a quote to repair it, because it really is a fantastic suspension, but if it's in the 4 figures, I'd bail for ICON. It would cost you more now, but at least it's done. That said, I hope you got a good deal on the truck, you'll love it.

 

[LBridges]

...

My questions are:

1. Do I HAVE to change the torsion bars, or does the "AHC torsion bars are not up to the post AHC job "argument hold
2. Any downside to putting in the more affordable OME torsion bars with the Toyota OEM shocks and springs?
3. MUST i drop the diff in the above situation if it will only leave it at approximately the AHC Neutral height?
4. Do I need another opinion? I do not want to chew up good money on diagnostic hours

From some things I have read (but not an expert so...

1. The torsion bars for AHC suspension rely on having the hydraulic boost. Even if you could twist the bar enough to get stock height it wouldn't be a good balance to the non-ahc shocks
2. Not sure, but I think all of these are made for increased height and so running at stock height is also not a good suspension/shock combination - read up on droop - think about vehicle suspension characteristics as the vehicle moves through the zero load point (twist from one direction to the other).
3. No, diff drop is only for changed height suspensions
4. Depends - try getting some advice from @PADDO - he seems to be one of if not most the most knowledgeable folks on AHC. That and consider acquiring one of the cloned Techstream devices via Amazon or EBay. Even if you don't do the work it will be comforting to know some data before asking a tech for help.

 

[mwk]

I had AHC on my first 06, and I have it on my current one. I love the system, and have always taken care of it in both trucks (flushes, adjusted TB's etc) but as seen as it shows the first sign of going south (i.e. any of the components needing to be replaced) it's all coming out for a traditional setup. I would get a quote to repair it, because it really is a fantastic suspension, but if it's in the 4 figures, I'd bail for ICON. It would cost you more now, but at least it's done. That said, I hope you got a good deal on the truck, you'll love it.

Thx m. I'm told the part I need is 1k. Cruiser parts said put in the stock shocks and springs an don't replace torsion bars just clock them a bit .... Thoughts

 

[mwk]

Also I do trailer a boat a bit but want ride and height as close to stock as possible

 

[camino70]

I'd search through user paddo's posts before I'd do anything. Just because someone said it needs an expensive part replaced doesn't make it so, it could be something easy and inexpensive.

 

[uHu]

Are you wrenching yourself, or will you have to pay dealer prices for work?

I very much doubt that you need a solenoid assembly. That's how the dealers work, change part after part until the problem is solved, or the owner ('s wallet) says stop. (even if the problem is a loose connector).

The problem with the ahc could be as simple as lack of torsion bar adjustment, or a faulty height sensor, but you really need techstream, and to read up on the system a bit.

If you are ok with conventional suspension, you just change the 4 springs (TBs & coils) and the 4 shocks. Remove as much of the ahc components as you feel like. OEM parts are good if you are running standard height. If buying 2nd hand, make sure the coils are newish, or get new coils. Coils are what wears fastest of the suspension components, both for ahc and conventional.

 

[mwk]

Are you wrenching yourself, or will you have to pay dealer prices for work?

I very much doubt that you need a solenoid assembly. That's how the dealers work, change part after part until the problem is solved, or the owner ('s wallet) says stop. (even if the problem is a loose connector).

The problem with the ahc could be as simple as lack of torsion bar adjustment, or a faulty height sensor, but you really need techstream, and to read up on the system a bit.

If you are ok with conventional suspension, you just change the 4 springs (TBs & coils) and the 4 shocks. Remove as much of the ahc components as you feel like. OEM parts are good if you are running standard height. If buying 2nd hand, make sure the coils are newish, or get new coils. Coils are what wears fastest of the suspension components, both for ahc and conventional.

THX uHu cruiser parts sells wo rears and all 4 toyota shocks, new for 499.00 could i use ome tb instead of the wildly expensive Toyota?

 

[mwk]

CODES ARE:
C-1718
C-1736
C-1764
C-1777


Feel free to respond.

 

[camino70]

Not sure how I missed lbridges response, but that's what I'd recommend to. I'd search or wait for paddo, but you should probably flush the fluid, ensure its properly full, ensure all the settings are correct in tech steam than reset the codes and see what codes trigger than.

If you do go with LC suspension, I'd look for OEM take off torsion bars with my second choice being ome torsion bars.

 

[mwk]

thx guys i reached out to Paddo

 

[dasgeek]

Congrats on your new truck. Once you get this sorted, you will love it.

I have a 2002 LX470 with 250K on it. I have the original AHC on it and it still works. I think the ride is a little stiffer (globes are slowly going out). Some day I may replace the system if something big fails or if I decide to add a lot of armor to the truck. If you are willing to spend some time checking out the system yourself, you can save a lot of money. I do not think many dealers really understand this system. They follow the service manual steps and replace items in the flow chart. That can get very expensive.

If you are not wanting to spend time evaluating yourself, then you may want to replace with OEM or nice 3rd party lift (Old Man EMU). If you are willing to spend you own time (and like to work on your vehicle), do some more reading on MUD. Here is one thread with some good info.

 

[dasgeek]

Also, one thing that can really screw up this system is add anything other that the Toyota AHC fluid to the system. I have seen posts where some service tech adds brake fluid to the system not knowing what it is. This can cause permeant issues in the system.

 

[PADDO]

Those codes implicate the pressure sensor cct and height accumulator solenoid/cct. As mentioned in my pm I'd check the integrity of the connector/wires to the height acc. solenoid and main solenoid. Pull the shroud off the height solenoid and check the wiring hasn't chaffed as that shroud is prone to keeping grit in. Do the manual dtc clear procedure and see if that unlocks the AHC ECU.
The main valve and height accumulator valve assemblies can be checked for continuity, pressure sensor can also be checked.

 

[mwk]

Paddo, if the wiring integrity cheks out ok, then what is issue in your opinion? Is it then time to change to standard suspension

 

[PADDO]

If your solenoid coils aren't open cct and the wiring/connectors check out I'd then look to the ECU outputs, if the ECU isn't sending the correct pulses (after fault codes have been cleared) to the height or main valve block solenoids then you'd consider a used replacement ECU. Having access to Techstream would help you a lot, but check the continuity of those solenoids and wiring first. If your height solenoid is open cct I've got a spare I'll loan you till you can source a used replacement
Going to conventional isn't without its own costs, but if that's ultimately what you want to do and better suits your needs then by all means do it. I just hate to see AHCs thrown out for relatively minor problems.