Looking at 2006 with blinky AHC... walk away?

[AppleTech]

So I'm looking at potentially picking up a 2006 100 with AHC. Overall the truck is in good shape and I am seriously considering it. I'll likely use AHC as a bargaining chip if it is indeed bad, but I don't know if I'm getting in over my head.

Symptoms on my short test drive (not sure what is normal and what is not - first test drive of a 100 ever):
- Truck idling in park, system did not move up or down when changing the selector
- Seemed to move about on it's own when driving (mixed city and highway) but did seem to move between states alot, and when I was in stop and go never stopped blinking on the dash.
- Never seemed to stick to the setting I put it to and on occasion just sat blinking.

If I get serious about this I will definitely do a longer inspection and really test it out, but I don't know anything about the system and I'm a bit overwhelmed by the search results here.

Any insights appreciated!

 

[Junglejack]

Hello,
AHC does lower at near highway speeds. Unless it was stuck in the "Low" position, most likely it is fine. Blinking is normal as it changes from "N" to either L or H.

This can take a hot minute to do. Moreover, retrofitting the standard suspension is quite common with myriad writeups. That said, most seem to be replacing it due to the additional weight of the armor not playing well with the AHC.

If i were a betting man, I would wager it is operational. If it was not, I would look kinda "slammed' to the ground and I think it would have made a strong impression.

 

[v8tuff]

My 04 is rock solid in "N" all the time unless I switch it to H or L. Sounds like a bad situation to me. I'd insist on a dealership estimate of repair or some kind of inspection before proceeding.

 

[AppleTech]

Should I expect it to be able to move up and down when truck is not driving? It did not seem to.

 

[Slickspawn]

https://forum.ih8mud.com/threads/ahc-problem.834439/#post-9558092

https://forum.ih8mud.com/threads/thinking-of-buying-a-lx-ahc-concerns.852207/#post-9702481

 

[Sandroad]

If you test drive again, grab the owners manual from the glove box and read the section on AHC operation. That way you'll know if it's working correctly. If it is not and you still want the truck, you have a huge bargaining chip for lower price.

 

[PADDO]

Sandroad gives the best advice so far, read up on the system because it's hard to know what bad looks like if you aren't sure what good looks like. OP, I believe I can explain the blinking light examples as normal operation: ie vehicle won't raise or lower if a door is open; stopped with foot on brake for more than five seconds and push H or L again nothing will happen; put it in H (or L) and start driving and it will come back to N. All normal operation. If you're interested PM me and I'll email some AHC pre check FSM info.

 

[brosama]

Use it as leverage to get a huge chunk off the price. Put some of that toward a lift kit. Head for the hills. Done.

 

[Bretthn]

I recently learned that a low battery or dying alternator (not bad enough to trip the dummy battery light) will prevent the system from working properly and give some of the same symptoms you saw. Just an FYI. You may be concerned about the suspension and find you have low voltage and need to replace an alternator soon.

 

[rustydrummer]

Yea, use it to negotiate the price down, then spend $800 and put an OME setup on it.

 

[TeCKis300]

Should I expect it to be able to move up and down when truck is not driving? It did not seem to.

Yes, but only when the engine is running and all the doors are closed.

 

[stridertexas]

Should I expect it to be able to move up and down when truck is not driving? It did not seem to.

I have an 07, and it will typically drop while still, but will raise when in drive or moving slowly.

I'd get it in low then drive off and see if it raises after 10mph. Then do the same with putting it in high and see if it lowers after 20mph.

Also can you tell if the AHC tightens up when moving between comfort and sport? I wouldn't just test the height control to determine if it's working properly.

 

[Weatherman]

Make sure you meet these conditions before trying to raise or lower with the selector button:
- Truck is in park
- Parking brake is set
- All doors are closed
- Engine running
- Foot off the brake
It will just blink and not raise/lower if the above conditions are not met.

 

[Bretthn]

Make sure you meet these conditions before trying to raise or lower with the selector button:
- Truck is in park
- Parking brake is set
- All doors are closed
- Engine running
- Foot off the brake
It will just blink and not raise/lower if the above conditions are not met.

Good information minus the parking brake. It is not required and will actually make the pump work harder as the rear tires need to roll ever so slightly as the rear axle will move forward or back a tiny bit as the suspension goes up or down. Mine doesn't like to move with the e brake on but works flawlessly without it.

 

[uHu]

The AHC is pretty solid. Even if there is a fault condition, it will serve you well after being fixed.
With a bit more info on the behaviour, I think we'll be able to diagnose it here.
The most common problem which could match your somewhat vague description, is related to sensors: Either misaligned, faulty sensor, or faulty/loose/stuck/bent linkage.

 

[Junglejack]

Especially considering how expensive 2006-2007 LC/LX's and the AHC concerns, I would recommend taking for a PPI either at a Lexus or Toyota dealership.

 

[Weatherman]

Good information minus the parking brake. It is not required and will actually make the pump work harder as the rear tires need to roll ever so slightly as the rear axle will move forward or back a tiny bit as the suspension goes up or down. Mine doesn't like to move with the e brake on but works flawlessly without it.

I stand corrected. I Just read the manual and there is no mention of the parking brake. I have been operating it incorrectly for the past few months. Thanks for the heads up.

 

[PADDO]

Make sure you meet these conditions before trying to raise or lower with the selector button:
- Truck is in park
- Parking brake is set
- All doors are closed
- Engine running
- Foot off the brake
It will just blink and not raise/lower if the above conditions are not met.

It will raise whilst moving in D as long as you're under the upper speed threshold (19mph iirc), so you're not limited to making a H selection in park.

 

[mgoblue]

My first thought...'were the doors closed?'

 

[AMGAndrew]

They AHC system isn't terribly complicated and easily servicable but replacement parts can be pricey if buying OE new if/when it does break. AHC is a really good system, better than a lot of people give it credit for. I wouldn't let AHC deter you from buying as long as you can come to terms with the seller regarding the current "issues". It could just have some air in the system and needs new fluid and flushed.