09 LX570 - AHC Failure (1 Viewer)

[aryanalp]

Greetings folks. I live in Toronto, Canada and I drive a 09 LX570 with 236,000 KM on the clock and few days ago the AHC started giving up on me.

It was a rainy day and the truck was driving fine, up until I added one luggage (probably 10-15kg) into the trunk and drove off. 5km later the infamous "Check 4 Wheel AHC System" came up - at this point the truck was still sitting at normal height so I changed course and drove back home to drop the car and cab it to the airport before further damaging any parts.

Researching online while I waited for my TechStream cable to arrive, I decided to drop the vehicle at the dealership to diagnose the cause. Note that at this point I could hear the AHC pump running and working for 1-2 minutes upon starting the car. After dropping it at the dealership for diagnoses, they came up with the following fault codes of C1714 & C1763; left-rear height control sensor is seized and abnormal oil pressure for pump motor and instructed to initially start by replacing the 89408-60020 - SENSOR SUB-ASSY, HEIGHT CONTROL, REAR LH (back order of 1 month) and then if the issue continues; replace the entire pump motor

So I ordered the height sensor and picked up the car until the part arrives in a month, however at this point, I could not hear the AHC pump running any more and the truck was sitting flat on the lowest height possible. The Lexus dealer did not sound very confident of their knowledge about LX platform or the AHC system; as a matter of fact they had very little knowledge about either of them. Hence I am creating this thread to seek your opinion, as the members here are more knowledgable about AHC system overall.

Anyway, the TechStream cable arrived today and I took couple pictures from the AHC tab to get some insights about any abnormal data/numbers that stands out to you folks. Note that the C1714 error appears as history and not current.

I have searched the topic and the code through the forum, but the one's I found were related to LX470 and not exactly LX570. I don't know much about the technicalities of the AHC system, and I'm not sure that the faulty height sensor could cause all this problem? Nevertheless, has this issue come up before? Could the abnormal oil pressure for the pump motor be a cause of the faulty height sensor?

Any sort of help or discussions are welcome to just get the ball rolling in the right direction while I await arrival of the part, as well as, to educate myself. It's also worth mentioning that the AHC oil was flushed about 5000 KM ago.

 

[razzyrazz]

I'm by no means an expert, but have fooled around in Techstream quite a bit. Did you run the AHC tests? Results from those might help others diagnose your issue.

 

[NYC570]

It might not be a coincidence that there's a failure right after a flush. You can check the hydraulic fluid level first, then try to restart the pump from techstream. Was the flush done at the dealership?

 

[tbisaacs]

It might not be a coincidence that there's a failure right after a flush. You can check the hydraulic fluid level first, then try to restart the pump from techstream. Was the flush done at the dealership?

this is where I would start

 

[grinchy]

I think low fluid level too, though inability to raise could be a pump. You'd think the dealer novice or not would've checked fluid level.

Switching out a height sensor shouldn't be a big deal.

 

[aryanalp]

Thank you all for your instantaneous responses.

@razzyrazz is there any specific AHC test I should be running or just overall trying the active test for every parameters within the AHC tab?

@NYC570 the AHC flush was done at my trusted garage; Cyrious GarageWorks. I wasn't sure when or if at all the previous owner had changed the AHC fluid, so I had it changed. After the flush, I could notice the quality of comfort improving, as well as, the time it would take the truck to raise or lower.

@grinchy & @tbisaacs - I doubt the dealer ever checked the AHC fluid level at all. They were not very familar with the LX series. I had to guide and explain to the technician as to what the AHC system is, he was under the impression there is something wrong with the 4 wheel drive system according to the dashboard warning stating "Check 4 wheel AHC system". I'll get some tools and open up the lid to check the AHC fluid level and get back to you guys!

Furthermore, while digging online I noticed some people experiencing the same error due to blown fuses. Would a blown fuse come up within the TechStream or I have to check for it manually?

 

[Phalen302]

Sorry to hear. Would recommend trying another Lexus shop. The title of this thread is misleading- it’s sound like total AHC system failure. The cause be no proper AHC fluid exchange, fuse, a globe or motor. I personally could not suggest solutions, ideas with out proper diagnostic. You can spend days on this goose chase.

 

[NYC570]

Thank you all for your instantaneous responses.

@razzyrazz is there any specific AHC test I should be running or just overall trying the active test for every parameters within the AHC tab?

@NYC570 the AHC flush was done at my trusted garage; Cyrious GarageWorks. I wasn't sure when or if at all the previous owner had changed the AHC fluid, so I had it changed. After the flush, I could notice the quality of comfort improving, as well as, the time it would take the truck to raise or lower.

@grinchy & @tbisaacs - I doubt the dealer ever checked the AHC fluid level at all. They were not very familar with the LX series. I had to guide and explain to the technician as to what the AHC system is, he was under the impression there is something wrong with the 4 wheel drive system according to the dashboard warning stating "Check 4 wheel AHC system". I'll get some tools and open up the lid to check the AHC fluid level and get back to you guys!

Furthermore, while digging online I noticed some people experiencing the same error due to blown fuses. Would a blown fuse come up within the TechStream or I have to check for it manually?

Did you buy the hydraulic fluid for the shop to do the work? If not, make sure the shop added the proper hydraulic fluid. I read a couple of threads where the shop added brake fluid instead of the hydraulic fluid. The hydraulic fluid is a lot more expensive than brake fluid.

 

[aryanalp]

Valid points gentlemen, it has been 14 days since I have ordered the height sensor and there are 14 more days to go until its arrival to Canada. While waiting, I have been researching other alternatives in case the issue does not resolve by changing the height sensor. Alternatives such as replacing the whole AHC pump and motor according to the novice dealer.

The dealer here in Toronto, Canada has quoted me the following parts with their respective price:

08886-81221	SUSPENSION FLU	4	39.50	158
91631-G0830	BOLT, W/WASHER	2	1.98	3.96
96341-11200	BOLT UNION	1	7.56	7.56
48942-60020	GASKET, HEIGHT	1	6.40	6.40
48997-60010	TUBE, HEIGHT CN	1	172.39	172.39
48999-60010	TUBE HEIGHT C	1	145.18	145.18
48998-60010	TUBE HEIGHT C	1	185.14	185.14
48910-60031	PUMP & MOTOR A	1	4419.18	4419.18

In total it rounds up to just a little over 5000 CAD (excluding labour). Pump and motor being the most expensive part on the list, I tried looking if it could be found cheaper somewhere else. The same so called genuine Toyota/Lexus part is available via ebay and ships from Japan for 800 USD to 1200 USD. My question is, has anyone tried the ebay parts and what's their feedback? It would really make a big difference in the bill.

Oh and if we have any other Canadian members from Toronto, Ontario, I would really appreciate your recommendation to a garage that knows a thing or two about LX series or AHC overall. The Lexus dealers I have tried, seem to be very novice about technicalities of AHC and keep up-selling the most expensive product and services to me.

 

[g1701gst]

What did you find with the fluid level?
Were you able to confirm what fluid was used for the flush?
Do you see any fluid leaks under your vehicle?

I had a cracked rear no 4 height control tube recently, lost fluid and it got stuck in the low mode because there wasn't enough fluid. I needed to drive home so I pulled the AHC fuse under the hood so the pump would stop running and prevent further damage.

 

[grinchy]

I just ordered four globes from eBay. They're due in later today. I expect them to be fine, will let you know if not. I won't be doing the replacement for a few more weeks, still gathering parts.

 

[nwfl4runner]

Motor is 48910-60032 (superseding part # I believe) and $990USD on Partsouq. All their stuff is legit.

 

[grinchy]

Globes look fine. PM me if you want the vendor I used @aryanalp .

I just reviewed the screen shots above. I suggest you do a manual height adjustment on your RR sensor and see if the techstream reading changes. As it is, it sure does look to be the odd one out. It is very easy to adjust the height, just loosen the nut and slide the little arm to another position.

 

[bloc]

These AHC systems have so few problems I’d personally be fine running an ebay pump if you find one cheap. That said, that price from partsouq is very compelling for a brand new OEM part.

 

[airforce1]

sorry to hijack this thread but how often should the AHC be flushed?

 

[LXCruza]

I second above question. I'm at 193,000KM and got really worried after reading this thread!

@aryanalp, I've bought multiple OEM parts from Partsouq on Ebay and they are absolutely legit.

 

[aryanalp]

Thank you for your testimonials everybody, you are a gentleman and a scholar.

Due to my parking location, the car sitting extremely low, and the lack of space in the wheel well I couldn't tool around much. Here is a picture of the AHC pump and its fluid. It is not clear enough, but from my understanding the fluid's there and not leaking? and yeah the shop has used the AHC fluid that's for sure.

As per other's inquiries about flushing the AHC, i am not an expert by any means but according to the maintenance manual it has to be replaced at 72 Months or 60,000 Miles and 144 Months or 120,000 Miles.

 

[airforce1]

Well if that’s the case then our AHC needs a flush. Thanks for posting!

 

[aryanalp]

Alright so finally the part arrived and my trusted mechanic was able to start working on her. Below is his finding:

Ok so we found that the right rear sensor was bent causing that sensor to be faulty, straightened it out, it worked fine, there is a connection problem with the Left rear sensor, we cleaned it and it seems to be working now, we will probably still replace that sensor with the one we have here. The main problem is the pump.. We bypassed the entire system and put direct power to the pump and it did not come on.. So your gonna need a pump. This job could get ugly, the lines back there going to the pump are pretty rusty, a bit worried about those breaking when we take it apart, in which case we would need new lines and such as well..

Given the depth of the issue, I'll be not hesitant in ordering a new AHC pump from the third party you guys have recommended. It will be both cheaper and faster then ordering from dealer. Just want to make sure if there is anything else we should be looking into making sure the pump is gone for good prior to making an order.

Suggestions and recommendations are all welcome, feel free to drop hints.

P.S: I have attached a PDF file that helps in diagnosing the error I was receiving. Couldn't find it on the forum and thought it would save someone else some time in the future.

 

[aryanalp]

Just to update and wrap up this thread; I ended up ordering a new pump, as well as, new lines from partsouq in addition to the height sensor that was ordered from the dealer. The shipment from partsouq came about 2 days after making the order and was shipped through FedEx. I was dinged with 380~ CAD in customs and duty charges for a package worth of 1700 CAD (in comparison to what the dealer was quoting north of 5000). The supplied parts were completely brand new and very well packaged. We replaced all the parts and now the truck runs smoother than ever. Thank you to everyone here who had helped pointing me out to the right direction, the partsouq peeps for the parts, and my mechanic and his crew for the top notch job.