AHC with harsh ride (1 Viewer)

[PabloCruise]

Is it possible the tires get stiffer as they dry out over time? How long have you been running the Hankooks?

 

[PabloCruise]

It's the short Ts & E1 in dlc1 test. It should identify if you have a non responsive corner, you can also measure the resistance of the step motor coils, 12-13.6 ohms between each pin to pin 2 (common return) at the dampers. Pin 2 is the centre one of the 3 pin row. Getting that neutral pressure down along with reasonable tire pressures is desirable.

Sorry to sound like a buffoon, but is there a more detailed description of how to run this test?

 

[ylexot]

Is it possible the tires get stiffer as they dry out over time? How long have you been running the Hankooks?

I have thought about that. These tires are less than 2 years old and have less than 10k miles on them (closer to 7 I think). I don't think they have gotten appreciably harder or stiffer. They were mounted on my 80 for a while and I had a similar harsh ride complaint with it, even after replacing the shocks. I love the traction on these tires. they've been great in the snow and ice, a couple little mud pits, and a few loose wet steep obstacles.

Attached is a pdf of some AHC diagnostic tests. Test 4 is the Ts/E1 DLC1 16 step test.

 

[PADDO]

Sorry to sound like a buffoon, but is there a more detailed description of how to run this test?

It's a very straight forward check to help identify if a certain corner isn't responding to changes in damping settings, starting at the softest position, 1 through to 15. For example it will identify a blown globe or a damper assembly that isn't responding to the ECUs commands, or a globe that has lost more charge than its counterpart. It is also very valuable in that you can set your damping to the softest response and go for a drive: you've locked out the electronic control aspect of the damping system so if you still feel the damping is harsh or unsatisfactory then you are most likely looking at a physical mechanical problem as opposed to an electronic control problem.
With the vehicle off short terminals Ts and E1 in the DLC1 connector. Start the vehicle, you are now in AHC test mode (Christmas tree dash lights flashing) and damping is set to 1, softest. Walk around and push/bounce each corner and get a feel for the response. Touching the brake pedal steps you to position 2 of the damping scale, again walk around and feel each corners' response. Repeat the brake pedal pushes and, hopefully, feel an even progressive increase in the effort needed to push down each corner.
When done turn off and remove jumper, re start and confirm that AHC lights are all back to normal.
Repeat the test if you wish whilst driving, note that the system will incrementally step up in damping each time you touch your brakes until above 3mph, so if you want to drive in position 1 then it's an idea not to have to reverse and brake to get out of your driveway or garage. Don't forget to remove the jumper on completion.
You can also drive with techstream running, AHC data screen selected and observe lots of things switch and changing.

 

[PabloCruise]

I have thought about that. These tires are less than 2 years old and have less than 10k miles on them (closer to 7 I think). I don't think they have gotten appreciably harder or stiffer. They were mounted on my 80 for a while and I had a similar harsh ride complaint with it, even after replacing the shocks. I love the traction on these tires. they've been great in the snow and ice, a couple little mud pits, and a few loose wet steep obstacles.

Attached is a pdf of some AHC diagnostic tests. Test 4 is the Ts/E1 DLC1 16 step test.

Thank you for the PDF!

What pressure are you running in these tires?

 

[PabloCruise]

It's a very straight forward check to help identify if a certain corner isn't responding to changes in damping settings, starting at the softest position, 1 through to 15. For example it will identify a blown globe or a damper assembly that isn't responding to the ECUs commands, or a globe that has lost more charge than its counterpart. It is also very valuable in that you can set your damping to the softest response and go for a drive: you've locked at the electronic control aspect of the damping system so if you still feel the damping is harsh or unsatisfactory then you are most likely looking at a physical mechanical problem as opposed to an electronic control problem.
With the vehicle off short terminals Ts and E1 in the DLC1 connector. Start the vehicle, you are now in AHC test mode (Christmas tree dash lights flashing) and damping is set to 1, softest. Walk around and push/bounce each corner and get a feel for the response. Touching the brake pedal steps you to position 2 of the damping scale, again walk around and feel each corners' response. Repeat the brake pedal pushes and, hopefully, feel an even progressive increase in the effort needed to push down each corner.
When done turn off and remove jumper, re start and confirm that AHC lights are all back to normal.
Repeat the test if you wish whilst driving, note that the system will incrementally step up in damping each time you touch your brakes until above 3mph, so if you want to drive in position 1 then it's an idea not to have to reverse and brake to get out of your driveway or garage. Don't forget to remove the jumper on completion.
You can also drive with techstream running, AHC data screen selected and observe lots of things switch and changing.

This sounds very useful! Thank you.

 

[ylexot]

I still haven't tried the step 1 driving test Paddo described. I've done it stationary and confirmed that suspension was doing what it was supposed to be doing. I should do the rolling version of the test just for fun. There is a wonderfully textured stretch of road in my neighborhood that I drive over every day, which is part of the reason this has been driving me nutso.

Tire pressure: factory 29psi front and 32 back.

 

[hkeller]

Need to do this this weekend. Can I use techstream to get it in the number 1 setting?

 

[chuckscap]

I had my AHC replaced by Slee. They did an awesome job. I had a $3000 within 60 day guarantee on my 2000 lx470 (I bought it for $9600, it came with a new set of 265/75/16 BFK KO tires) and Lexus came back and said the AHC repair was $3600 just in parts, so the Nissan dealer whom I bought it from paid me the $3000. I had Slee put in their 1.5" OME lift kit with diff drop and SPC UCAs and I love everything but the OME Nitro Sport shocks. I'm replacing them with OEM Toyota LC shocks soonest. If my AHC was functional or repairable I would've kept it, but it wasn't.

 

[PADDO]

Need to do this this weekend. Can I use techstream to get it in the number 1 setting?

No, not that I'm aware of and I've spent an hour or three trying. Techstream lets you do AHC functional tests in the utility section to check solenoid operations and the like but the only way I've found to put the system into damper check mode is to short Ts and E1. It's an fsm procedure, not an unapproved hack if you're concerned about shorting out terminals as I know some aren't comfortable with doing things like this.

 

[PADDO]

I had my AHC replaced by Slee. They did an awesome job. I had a $3000 within 60 day guarantee on my 2000 lx470 (I bought it for $9600, it came with a new set of 265/75/16 BFK KO tires) and Lexus came back and said the AHC repair was $3600 just in parts, so the Nissan dealer whom I bought it from paid me the $3000. I had Slee put in their 1.5" OME lift kit with diff drop and SPC UCAs and I love everything but the OME Nitro Sport shocks. I'm replacing them with OEM Toyota LC shocks soonest. If my AHC was functional or repairable I would've kept it, but it wasn't.

Sounds like you made out like a bandit! In your case these ridiculous Lexus dealer quotes of $3-4K worked out for you, I feel for those that pay these "replace everything" prices when in the majority of cases it simply isn't warranted or justifiable. Do you happen to know what parts they proposed to replace? Likely 4x globes and 4x shocks?

 

[hkeller]

Thanks, again, Paddo. In that case, I will download the FSM pages and give it a shot.

 

[chuckscap]

Sounds like you made out like a bandit! In your case these ridiculous Lexus dealer quotes of $3-4K worked out for you, I feel for those that pay these "replace everything" prices when in the majority of cases it simply isn't warranted or justifiable. Do you happen to know what parts they proposed to replace? Likely 4x globes and 4x shocks?

I assume Slee either trashed them or has them.

 

[PADDO]

I was curious as to what parts the dealer proposed to replace for $3600, doesn't really matter as it all water under the bridge.

 

[chuckscap]

I was curious as to what parts the dealer proposed to replace for $3600, doesn't really matter as it all water under the bridge.

I don't remember, I do know that didn't include labor

 

[hkeller]

Ok. I have not had time to dig into this, but the ride is definitely better when it is warmer, and even better if it rains. Am I nuts? Maybe warmer and damp
equals better contact at the height sensors? Stumped.

 

[hkeller]

I've read most if not all of the recent AHC threads and haven't found my solution. I bought the TechStream software, have pressure within spec front and rear (didn't write the pressures down but they were in spec when I tested them last week), flushed the fluid, etc. The AHC system is functioning just fine as best I can test it (other than a squeal from the pump when reaching max height).

My problem is a harsh ride. The AHC works well on medium and large bumps, but the suspension is transmitting a far harsher ride than it used to for small bumps - more like texture in the road. The best way I can describe it is that rough ride feel you get with tire pressure through the roof or on a car with super low profile tires. Every crack or seam in the pavement seems to pass right through the suspension for a harsh ride where my LC used to ride like a cloud.

Assuming my testing is right and the AHC is functioning fine, what else could I look at? Are there bushings that could be shot?

If it helps - 2007 LC, but low miles (about 60K miles). This seems to have either started or gotten worse when I got a new boat that has a much higher tongue weight than my previous boat. The tongue weight overwhelms the AHC and I'm wondering if the extra weight "crushing the suspension" could have ruined some kind of dampening that used to be in the suspension somewhere. I have to admit I'm not much of a mechanic and don't know much about my suspension design, though I'm picking it up from this board and trying to figure out my AHC.

Sorry for resurrecting's this old issue, but I have been doing a bunch of AHC reading and it seems many of us have this issue, and it has never been solved. I have yet to see whether a mere flush of the system fixes it. Many people on Mud and Club Lexus say things like, "It's worth a try", but no one has said, Wow, I flushed my system and it fixed the harsh ride." On one of our LXs, replacing the globes and then getting the pressure in spec didn't fix it. Is it an AHC ECU issue?

I now have a LX 570 the dealer can't sort out and I don't really feel like laying in the cold in my driveway replacing the 10 accumulators it has and flushing the system, if that won't fix the problem.

Any ideas? Thanks!

 

[CivicFerio]

Sorry for resurrecting's this old issue, but I have been doing a bunch of AHC reading and it seems many of us have this issue, and it has never been solved. I have yet to see whether a mere flush of the system fixes it. Many people on Mud and Club Lexus say things like, "It's worth a try", but no one has said, Wow, I flushed my system and it fixed the harsh ride." On one of our LXs, replacing the globes and then getting the pressure in spec didn't fix it. Is it an AHC ECU issue?

I now have a LX 570 the dealer can't sort out and I don't really feel like laying in the cold in my driveway replacing the 10 accumulators it has and flushing the system, if that won't fix the problem.

Any ideas? Thanks!

I have my 06 LX470 since new and I can't remember how it rode when new, it may felt exactly the same. It currently has 80K miles and I do noticed the impact harshness on cracked pavement on city streets and freeway expansion joints. But I feel that is not as bad as many people suggest. I have an 2008 Tundra 4X4 ( SOLD ), 1997 80 series and a RAV4 EV to compare it against and the LX does not jump out in term of ride harshness when I switch vehicles it actually is the opposite. It may just be the characteristics of the a heavy unsprung mass components on our vehicles.

 

[OEMGUY0720]

A little off-topic for AHC equipped LC and LX owners. Do you guys notice when the rear door (passenger or driver side or even the rear tail gate/hatch door) opens, the AHC lowers the truck down (I've noticed this when the suspension is on N (neutral) setting I thought I was experiencing vertigo. Has this happened to any of you too?

 

[Mbchance]

A little off-topic for AHC equipped LC and LX owners. Do you guys notice when the rear door (passenger or driver side or even the rear tail gate/hatch door) opens, the AHC lowers the truck down (I've noticed this when the suspension is on N (neutral) setting I thought I was experiencing vertigo. Has this happened to any of you too?

Not that I’ve noticed. 07 Lx470

When the car is running?