Finally fixed my AHC! Changed pump~ (1 Viewer)

[Joe422]

Like some of you, I had my AHC issues ('04 LX, 120k miles)... and I tried swapping Actuator globes (both B&B and new OEM)... then swapped out the front shocks... tried to bleed, and failed 1/2 way through the process. Then thanks to BonS' posts, I ordered a new AHC pump sub assembly. Meanwhile I managed to install new rear shocks as well.

My final problem was the AHC pump sound was loud (at least I new it was spinning), and it couldnt get any pressure. The fluid in the reservoir never moved, and the suspension was just at the lowest setting.


First I drained the reservoir. Luckily I have a fluid evacuator (suction pump/tank) that made it simple to empty the AHC fluid. I can't imagine not having one in the garage.
Installing the new pump was very easy. I swapped out the new AHC pump subassembly, new O-rings (2 of them), new AHC motor seal, and the shaft coupler (I didn't have to do this, but it was just a precaution, and only cost a couple bucks). It must have taken 30 mins. All you need is a 10mm socket, 10mm box wrench, and an allen tool (for the actual pump.. sorry, forgot size)
I paid a little over $300 for the new pump sub-assembly, Orings, motor seal, coupler, and 2 cans of AHC fluid w/ tax. Not too bad (compared to the other AHC hardware)

Next fill the reservoir almost to the top! Once the car started (w/ jumper on the diagnostic connector for manual pump override) I couldnt hear the pump sound. A little concerned, I check the reservoir and the fluid was 1/2 gone! It primed itself, and pressurized the system so quick, and so silently! I raised and bled the 4 actuator globes, and the height accumulator about 2-4 times each, and went through almost 2 cans of AHC fluid.


Now the ride is smooth, the height changes quickly and silently (no more sudden drops and rises), and the AHC fluid gradation change is spot on.
Thanks to everyone who posted their tips and advice, and also for BonS who posted info about the pump sub-ssembly!!


**Tip: Be very careful w/ the 2 sensors on the Pump unit. the small one is temp sensor and cost over $45... the bigger pressure sensor is a whopping $400!!. You don't have to remove these, so just be careful w/ them.

-Joe

 

[uHu]

Joe,
Some great posts from you on the AHC system. Thanks.
We need this kind of info as the T0yota mechanics with ahc knowledge are hard to find.

 

[Joe422]

Thanks... Just glad we have these forums to share info and tips...

btw, if anyone needs to replace their AHC pumps, here's some part #'s...

48901-60010 Pump Sub-Assy
90301-70003 O-ring (big)
90301-06012 O-ring (small)

optional:
90311-10001 Oil Seal (motor) <--- not a must, but very easy to change... and just couple $$. I'd say it's worth it
04977-60010 Motor/pump coupler <---- not a must, but less than $1.50

08886-01805 AHC fluid 2.5L (x2 cans)


The pump itself lists for $291 at my local Lexus dealer... but they can be found in the low $200 range.

 

[NC-Grayson]

Thanks... Just glad we have these forums to share info and tips...

btw, if anyone needs to replace their AHC pumps, here's some part #'s...

48901-60010 Pump Sub-Assy
90301-70003 O-ring (big)
90301-06012 O-ring (small)

optional:
90311-10001 Oil Seal (motor) <--- not a must, but very easy to change... and just couple $$. I'd say it's worth it
04977-60010 Motor/pump coupler <---- not a must, but less than $1.50

08886-01805 AHC fluid 2.5L (x2 cans)


The pump itself lists for $291 at my local Lexus dealer... but they can be found in the low $200 range.

Bumping this up for anybody who has replaced their AHC pump sub-assembly

What is this 04977-60010 motor/pump coupler? I see nothing of that part number anywhere, and these parts diagrams aren't that common either.

I know it's not necessary...but...when in Rome right?

 

[uHu]

I think he actually means this one:

 

[JessPurviance]

My AHC is on the fritz. The pump seems to be struggling to raise the vehicle. It is making a squeaking sound when engaged. It fails about 20% of the time, turning off the AHC system. Symptoms started after I crossed a flooded road last month. Maybe the cause or maybe just coincidence.

My question is if I need to replace both the motor and pump? Or just one of them?

 

[namsag]

Congrats sir I salute you for fixing the system instead of just ripping it out. I am one who believes that AHC is worth repairing and maintaining. Thanks for the post on this.

 

[uHu]

My AHC is on the fritz. The pump seems to be struggling to raise the vehicle. It is making a squeaking sound when engaged. It fails about 20% of the time, turning off the AHC system. Symptoms started after I crossed a flooded road last month. Maybe the cause or maybe just coincidence.
My question is if I need to replace both the motor and pump? Or just one of them?

Start with some checking, instead of changing expensive parts until you find the problem.
Typical ahc fault after water crossing is sensor fail.
What are your pressures and heights, both reported height and physical height?

 

[JessPurviance]

Start with some checking, instead of changing expensive parts until you find the problem.
Typical ahc fault after water crossing is sensor fail.
What are your pressures and heights, both reported height and physical height?

Welp...

 

[uHu]

Pressures have to be read after moving to N from Lo. The idea is to check that your front and rear pressures are not abnormally high, because that would make the pump struggle. Assuming you'll be able to move it from Lo to N, if it works 80% of the time... And before doing that, measure actual height, front and rear, otherwise the pressure readings are skewed.
From your screen shot, it looks like the sensors ar OK, if they also give consistent readings when in Lo and Hi.
Next steps are checking pressure sensor, relay, motor, and bleeding pump. Could also be contamination of the fluid.
Se attached.

 

[JessPurviance]

Thank you for the help. I forgot I needed to adjust the height to read the pressures.

I figured out my problem and it was just low on fluid. I should have figured it out a while ago. I went about diagnosing this problem all wrong. Anyway, topped it off and now it is working fine. The reservoir is a little hard to see the fluid through and I never checked it properly. I shined a flashlight on the side of the reservoir and sure enough, at N the fluid was at the bottom, way below the min mark.

Thanks again. Sorry for wasting your time.

 

[uHu]

The fluid doesn't disappear by itself. You either have a leak, or flat globes (aka gas springs or gas chambers). The latter is more common. Is the suspension working well? How many graduations fluid level change from Lo to Hi?
PS
There is no wasted time. We learn, get to share info and gain knowledge and experience.

 

[JessPurviance]

The fluid doesn't disappear by itself. You either have a leak, or flat globes (aka gas springs or gas chambers). The latter is more common. Is the suspension working well? How many graduations fluid level change from Lo to Hi?
PS
There is no wasted time. We learn, get to share info and gain knowledge and experience.

You're right. Thanks for the response. I think one or more globes must be flat. I don't have a leak. I will check the graduations this weekend and try to figure this out. It is riding rougher than in the past.

 

[J1000]

Thanks for the help and part numbers in this thread. I preemptively changed my AHC pump subassembly and flushed the fluid at the same time. It was very easy, definitely sounds more intimidating than it is. I wasn't really having any trouble but every once in awhile I would notice the ride height drop suddenly and then come back up. And one time earlier this winter when it was the coldest I heard a noise from the pump for a few seconds on first start up. Both of which I think is indicative of a failing pump. The pump was pretty cheap at $159 on partsouq.com so I went for it and changed some seals too. I can't say for sure, but I think it raises up faster now than it was before. Ride quality is slightly better I think also. Very happy!

I did have a scare when I first started up after doing all the work and the AHC OFF light was blinking and nothing was working. I turned off the vehicle and wiggle the connections to make sure everything was tight and disconnected the battery for a minute or two and then tried again and it all worked perfectly.

I used this brake vacuum bleeder to remove the old fluid and it worked quick, easy and clean: https://amzn.to/2xf2fd2

Lowrider

 

[saudi]

Thanks for the help and part numbers in this thread. I preemptively changed my AHC pump subassembly and flushed the fluid at the same time. It was very easy, definitely sounds more intimidating than it is. I wasn't really having any trouble but every once in awhile I would notice the ride height drop suddenly and then come back up. And one time earlier this winter when it was the coldest I heard a noise from the pump for a few seconds on first start up. Both of which I think is indicative of a failing pump. The pump was pretty cheap at $159 on partsouq.com so I went for it and changed some seals too. I can't say for sure, but I think it raises up faster now than it was before. Ride quality is slightly better I think also. Very happy!

I did have a scare when I first started up after doing all the work and the AHC OFF light was blinking and nothing was working. I turned off the vehicle and wiggle the connections to make sure everything was tight and disconnected the battery for a minute or two and then tried again and it all worked perfectly.

I used this brake vacuum bleeder to remove the old fluid and it worked quick, easy and clean: https://amzn.to/2xf2fd2

Lowrider

i did the same thing replaced pump and nothing worked, after checkineverything else i hadnt pushed the connector on properly

 

[BonS]

Well, after all these years I'm back! My replacement AHC pump failed again. My OEM replacement pump lasted about 10-13 years which was way longer that the original. After the original pump failed I quit using the raise/lower function and just left it in the middle setting permanently. This seems to have extended the life from about 5 years to about 12. It's fun to find this thread and to see that my write up about replacing the pump instead of the entire pump assembly has helped others. Cheers!!