2009 LX 570 ACH Pump Not Working after picking up from Body Shop

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Joined
Apr 2, 2021
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3
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63
Location
chicago
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?
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Any thoughts?

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Solution
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...
If you have ‘good’ ride at any time it is probably not accumulators, though these could be replaced at this age and mileage.
Sounds to me like you’re losing pressure as the pump is intermittently getting power.

It may take a few days to track down the root cause.
Order a tech stream cable, we will need that. I recommend the vxdiag option.

It may be that there is a computer fault, if that’s the case it could be cost effective to just put in a normal suspension rather than replace the computer four accumulators and possibly the pump. With the accident it could be that enough stuff got messed up that repair will be difficult to find a single cause.

don’t know yet because we can’t tell what is wrong on the computer side.
Im about to pull the trigger. My greatest fear is having an 11 year old rig sit idle 42 days. Ive always heard dormancy in old vehicles is the root of all electrical issues.
 
Again, I appreciate all the advice I've received. Not trying to beat a dead horse, but the fuse to my horn blew. WTF, right. Related?
Once Again, I went over all the fuses in the engine compartment for a 2nd and 3rd time cuz of this.
The little yellow pick with the green light, showed 100% green aside from horn. I own a multimeter, but barely know how to use it.
And, thought using a MM when checking continuity should be a 1 or close to zero.
My findings showed everything in the red circle to have a number much higher than zero. Everything not highlighted or in green was 0.
27-30 are bolted and didn't test but wish I was able. Anyway, I read somewhere much of the AHC is correlated to #1 A/F exhaust sys.
Using the MM at 20k, I was getting .14 for #1 even after replacing fuse. But, after replacing #3,4 fuses, #1 now reads zero.

Oh yea, the 3rd row seat was making a weird noise, but worked. The Hatch, I had to manually close, but worked once the engine was started.

Long story short, horn prompted all this and admittingly I don't know what the hell I'm doing, but does any of this data make sense or possess any value in terms of understanding the AHC problem?

lexus fuse.jpg
 
Also, that Blue wire that was burnt showed in earlier thread, for some reason I'm thinking that belongs to the video system. But, I'm not sure. The beating the car has taken appears to have fixed my RR TPM at least temporarily so that's good. Hell, maybe the fixed wired radar detector will start working again.

last note, when I click ignition twice where everything powers up but no engine, It appears i have 10 volts, but after it cranks, I have 13.5. Is that normal?
 
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?
 
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
 
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 issueTh
I'm full of hunches, that's all I have. I'd take this as an outcome. Can't be too much to reset all this crap. But, how could an accident have caused this?
 
I'm just going in there tomorrow and waiting. Telling them to run the diag and print out. And, to tell me how it is possible for my accident to have caused this.

Period. below is a quote from the guy that put that full dissertation out on the ACH and full rebuild/restore. And, that's my point. Impact could easily have dislodged old corroded 5 years in snow censors and connectors.

All they must do is make the connection and then they can go balls to the wall and rebuild the whole lexus as far as I'm concerned. She's already priced out 4200 in the estimate, which is funny since there is no data for that quote to be based off of.

"be VERY careful when disconnecting rusted/weathered/corroded/dirt-fused connectors."
 
$4200 just to diagnose?! It’s becoming a money pit. At that rate, you may save by just selling or trading it in.
 
Back from the dealership with the diag. The Tech indicated left rear sensor needs to be replaced and something to effect of an arm that identifies the height snapped. Tech said he temp taped the arm together to complete the rest of the diagnostic and everything came back smelling like roses. Said pumps great.
He said the all the sensors are pretty bad and need to be replaced, but they work.

So, my hunch was right on and praise the lord for that. Thanks @grinchy and tech300 for your insight. Couple other things I thought I'd share:
1) they balked at doing a flush. They said leave it. So, that says something about their integrity not wanting to hose customers.

Well, actually, just 1 thing.

TeCKis300


ach_diag.png
 
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.
 
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.
He must of found it before the other sensors froze crashing the system thus requiring recalibration.
Is that fair to say? Thinking the recalibration you'd want done at the dealer, no?
 
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.
 
also wondering if they will take a close look at the spring since the car has taken a beating...there was a couple real bad bumps...loose your breath bad.
Or, does the calibration insure the whole system is intact including the spring
 

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