2009 LX 570 ACH Pump Not Working after picking up from Body Shop (2 Viewers)

[ohlancaster]

Hello Everyone. I've found this site very reliable and helpful over the past couple of years. Now I'm seeking advice on how to handle my situation regarding my 2009 LX 570.

I've lost power to the AHC pump 175 miles or 3 days after getting vehicle back.

Important notes regarding my vehicle: Average 300 plus miles a day for the past 2 years or 200,000 miles over the past two years. I've had one issue with the vehicle in all 11 years. Lexus LX 570 is a beast.

Notes about my issue:

-Rear-ended on the freeway in poor icy driving conditions 6 weeks ago whereby my vehicle sat dormant during 40 days to repair. Primary Impact Rear of vehicle sliding into wall.

-Last Monday, I finally was able to accept the vehicle after 42 days to repair. Driving home, I noticed a lot of looseness in the steering and the ACH check 4 wheel alert popped up.

-I removed one of the AHC fuses on the passenger side fuse box before a long trip home in order to protect the pump. Haven't been able to get the pump to work since.


I've driven this vehicle very hard over the past 2 years. It doesn't break. I contacted the insurance company that was paying for everything and I was advised they will cover the breakdown only if the mechanic will announce the accident played a role in this defect.

Whatever my issue may be, I know the accident resulting in my car sitting dormant would be the straw that broke the camels back. Are there not a hundred ways to articulate how an accident might have resulted in the straw that breaks the camels back?

Both the body shop and the lexus dealership have told me over the phone there is no correlation between this happenings and the accident. I just find this hard to believe.

Couldn't something that was about to break due to 285,000 miles become exacerbated by a major rear impact collision and gradually break during those 175 miles I drove after picking up the vehicle?
\
Any thoughts?

 

[TeCKis300]

Can you clarify what you mean by you lost power to the AHC pump? Any chance you have techstream to get the actual CEL/MIL codes?

I would check the AHC reservoir first (behind passenger rear tire well). Is there fluid in there? Plausible that the accident caused a lead in the system that allowed all the fluid to bleed out over the 175 miles?

 

[grinchy]

I've got a 730 at Lexus tomorrow am, but it's barely drivable now. I filled up with gas earlier so I am not sure if it has worsened or if the gas load is an explanation to the recent deteriorated state.

Maybe premature till the data is pulled, but it's not a leak issue, the system will work once after a reset, but i've only observed elevation using H and H only.

Then it appears to go into alarm state for obvious reasons and unable to bring it down sitting still. You got to get on the road and that's just to get it to where the rear drops. So, i don't believe fuses play a role except if #27 - ALT is the culprit. Life would be so great if it were!

So, it's not a total system failure. The pump functions, lifts, but favoring the driver side by 2.5 higher than pass. Further, it also favors driver side after it's failed and dropped. So, that's a clue. Maybe the control system is fried, but wouldn't it just not work in whole. I think it's fair to say that the things that are trying to work aren't broken. What's broken is what is causing that 2.5 variance in height between driver and passenger side. I don't know crap, but I'd still bet that if it were the computer, it would be a total failure.

Can something small cause the right to fail? I don't think the rear dropping is any indicator there is something wrong specific to hardware back there. The rear dropping is what happens automatically once the computer detects alarms and then shuts down.

What could cause that 2.5 variance?

There was a member in Minnesota that had a persistent side or corner inbalance. It ended up being the computer.
post accident there are several baselines that need to be reset, calibrations etc.if this wasn’t done it could be contributing to the issue

 

[grinchy]

well a broken arm on the sensor would do it . . . a member on here replaced one themselves with an itty bitty steering link, I didn't bookmark the page but it was $15 or less if I recall

thanks for the DTCs.

 

[grinchy]

I was casting about for likely causes. The fsm has a couple calibration activities to do after making adjustments to the sensor offsets. Most skip them and it’s fine.

yes you can see the height control sensors from under the car. They are little levers attached to the suspension. Like 4 inches long.

 

[grinchy]

Post in thread 'LX570 AHC height modifications (lift it!)'
LX570 AHC height modifications (lift it!) - https://forum.ih8mud.com/threads/lx570-ahc-height-modifications-lift-it.971211/post-10803147

 

[grinchy]

Body shop should have found the broken arm then.

yes, but most body shops would not be educated on how AHC works. Perhaps the biggest downside of the system is that it is not installed on very many vehicles, so the typical mechanic won't be familiar with it.

 

[TeCKis300]

You're making solid progress! Hang in there as I think you're getting to the root of the issues. I believe there to be 2:

1) First thing I would do is address the firm items. A single broken height sensor/misadjusted sensor is enough to cause all the issues you've described. I wouldn't jump to conclusions that the AHC ECU is faulty as that's exceedingly rare. Replace the broken arm but also have them evaluate whether the potentiometer (arm angle sensor) has been damaged/bent, or anything else in the vicinity. They'll need to properly setup the calibration on the new arm/angle sensor for the system to work properly. This last calibration - there's very real potential for the tech to not have enough skill in this area and you may need to step in with the hive minds help. @radman is a master at this.

2) Separately for your electrical gremlins, I suspect with the amount of time the car was in the body shop, they've killed your battery by letting it deeply drain. That can cause all sorts of non-descript issues. Get a replacement battery before chasing anything else.

 

[lx200inAR]

Have you verified the broken sensor arm? Could you post a picture? I'd love to see how one of those could be broken, without there being considerable damage around it. Wonder if during the collision something grabbed it as it went by and yanked on it. They are attached between the frame and upper control arm in all 4 spots. The two rear arms don't look identical, but the two front arms do. You can see the front arms from outside the wheel well, Just look over the top of the tire. The rear you have to climb under, but don't have to remove anything.

I also second the replacing the arm (also could check ebay for replacement part) and changing battery before doing anything else. If you are only getting 10v off the battery, it's probably pretty much toast. You could try just charging it, but if you drove for 2 hours and it was still 10v after that, doesn't sound good.

 

[grinchy]

Is it in L or N? I had that same error recently and it was a not quite seated connector back by the trailer wiring harness. Right rear near the body mount.
here’s a pic
The lower one is for the AHC pump and sensors.
Unplug and replug it.

the AHC dtc can Definitely be read in tech stream. Those will help a lot in determining what is up.

 

[ohlancaster]

Yes, I say "lost power" because I never heard the pump working days after messing with the fuse. I performed that reservoir check and it showed the fluid at maximum capacity as the vehicle being in the "low" state. Ii learned to check this from previous threads from this forum.

I have tried 4 low position, waiting for lights, turning off and the restarting. That somehow did affect or change the way the vehicle handled, but it did not affect the height or activate the pump. Normally, the pump can be heard cycling through, but still nothing.

Coincidentally, my Escort Passport 9500, which is a direct wired Radar, stopped working right after the accident. I decided to try and trouble shoot problems, and while searching , I found this burnt out wire that runs vertically from rear of vehicle along side of the passenger floorboard...Underneath the silver lexus outer floor trim that aligns underneath the door.

I'm wondering if this blue cord might be the pumps power source.

I recognize there are so many possibilities here. But, since the pump reservoir is full and I never heard any kind of alarming sound from the pump like it was failing, I figured this had to be electrical.

Perhaps I should wait until I get the diagnostic back from Lexus to try and glean how this accident contributed to whatever has failed.

It's hard to believe I can go from 300 miles a day for a couple of years uninterrupted and now suddenly this happening so soon after the vehicle sat dormant while being repaired, and it not being a byproduct of the accident.

 

[ohlancaster]

Is it in L or N? I had that same error recently and it was a not quite seated connector back by the trailer wiring harness. Right rear near the body mount.
here’s a pic
The lower one is for the AHC pump and sensors.
Unplug and replug it.

the AHC dtc can Definitely be read in tech stream. Those will help a lot in determining what is up.
View attachment 2633981

I tried this...and it's in the "N" position when I turn it on. If I initiate the 4 low and kill the engine, restart, It starts to the N with the Arrow pointing up. However, no pump action. I can detect some variation when I begin driving immediately afterwards, but without the pump making any noise to indicate it's active.
When adjusting the control switch setting to high or low from that point, I lose the arrow from the center box, but the text does appear,. i.e High, Low, Normal.

If I stop and restart the engine after losing the arrow, the arrow remains lost upon restart even though it indicates it's switching to "normal." The only way I can get the the arrow in the box with the 4 low hack or whatever.

 

[grinchy]

The dealer will pull the codes, the issue will likely be in the wiring or physical damage to a hardline. I’m sure like you that its a wiring issue from the accident or the repair. That is how mine was behaving when the connector was loose, I had N, it the height switch had no effect and no arrows. there isn’t too much wiring for the AHC, so it will hopefully not be a complicated fix.

 

[ohlancaster]

The dealer will pull the codes, the issue will likely be in the wiring or physical damage to a hardline. I’m sure like you that its a wiring issue from the accident or the repair. That is how mine was behaving when the connector was loose, I had N, it the height switch had no effect and no arrows. there isn’t too much wiring for the AHC, so it will hopefully not be a complicated fix.

Yeah, thank you. I read all your posts or threads rather. I've read just about everything on this matter. I just wish I was more technical and could perform these voltage test or resistance as attached. I found this I believe from this sight...maybe club lexus.

My hunch is with the mulitmeter being the best start. But, I bow to all of you folks that are way more knowledgeable. I just wish I hadn't touched anything as I'm now feeling complicit and reckless having possibly ruined my chances for recovery from insurance.

 

[ohlancaster]

Is it in L or N? I had that same error recently and it was a not quite seated connector back by the trailer wiring harness. Right rear near the body mount.
here’s a pic
The lower one is for the AHC pump and sensors.
Unplug and replug it.

the AHC dtc can Definitely be read in tech stream. Those will help a lot in determining what is up.
View attachment 2633981

Wait, the sensor I pulled was directly accessible from the little panel in the rear well. I don't think what I unplugged is the same as this at least from this visual.
I'll hop underneath and take a look tomorrow. Regardless, I'm going to be all over this again tomorrow. Hopefully I don't cause more problems than I've already got.

 

[grinchy]

Wait, the sensor I pulled was directly accessible from the little panel in the rear well. I don't think what I unplugged is the same as this at least from this visual.
I'll hop underneath and take a look tomorrow. Regardless, I'm going to be all over this again tomorrow. Hopefully I don't cause more problems than I've already got.

For orientation those two large bolt heads are where the rear tow hook bolts. I have an aftermarket bumper so my frame rail may look different.

you just pulled a fuse, that is not something they can hold you liable for.

 

[grinchy]

When the shop tells you the dtc that will certainly help us figure more closely what is going on.
Did the ahc work and you had arrows when you got the rig back?
And what do you mean by loose steering?

 

[ohlancaster]

@grinchy I reviewed your old posts and appears you have a great rig. You need a train horn from hornblasters.com.
That aside, yes, the AHC did work the day of receiving the vehicle and driving 135 miles of the 175 miles. Arrows yes.
Loose steering might best be described as the difference between how steering feels when in normal or low versus high high or just high.,
if you know what I mean.

 

[grinchy]

You need a train horn from hornblasters.com.

I'll take that under advisement

Failure en-route? Hmm. There are several options from failed hardline (you'd have fluid), to what you suspect with pump prime, to an electrical issue (likely since you've found some smoked wires). We really need the DTC.

Definitely replug that specified connector, it might not have been well seated when they had the rear end apart. Inspect it for burn when you have it apart.

 

[ohlancaster]

@grinchy I reviewed your history

I'll take that under advisement

Failure en-route? Hmm. There are several options from failed hardline (you'd have fluid), to what you suspect with pump prime, to an electrical issue (likely since you've found some smoked wires). We really need the DTC.

Definitely replug that specified connector, it might not have been well seated when they had the rear end apart. Inspect it for burn when you have it apart.

You guys are great. Unplugged and plugged the sensor located above the tow hooks as advised and wha la.

So now I have arrows and a functional pump. However, upon test drive, any hard breaking or speeding through curved declivities prompts the AHC warning and I lose arrow and N remains static as pump doesn't engage.

Interesting observations:
1. about 3 minutes for the the arrows and pump to engage after resetting sensor via plugged/unplugging.
2. Driving in high causes the steering wheel to rotate 20 degrees to the right and vehicle to veer right.
3. Back to square one with no arrow and no pump action, after a minute, resets and arrow.
4. Perfunctory measure tire to paint at N
Lr 5.0 / Lf 5.5
Rr 4.75 / Rf 4.88
5. Apologies for the pics, but at H, it's bad
Distributing height and clearly left side is higher


So, little disclaimer in that I've had periodic AHC warnings when breaking hard, but it would pass and everything has been normal UNTIL THE ACCIDENT.

I'm betting this new info provides way more insight into what's happening.

How can I link this to the accident?
Anyone have a confident answer to this puzzle?