AHC Help Needed - 2007 Land Cruiser

[blitt]

2007 Land Cruiser with 198,000. We just purchased this vehicle and PO had not flushed the suspension fluid for at least last 80k miles so decided to do a flush. Followed this procedure:

AHC Fluid Change How To -- Need Input

I'm planning on changing my AHC fluid this weekend, and have done a lot of research as to the best methods to use. Everything I found was kind of spread out, so i took some time to combine it all into one step by step document (attached). Since I've never done this myself, was looking for...

forum.ih8mud.com

Drained accumulator first, start vehicle for a minute, then drained from drivers side front globe. Back to start the vehicle and the AHC pump runs but after trying for about 15-20 seconds, it stops and the AHC flashes off and height stays in Low. I had removed the old AHC from the reservoir and put about 2.25 quarts of new back in.

Would anyone have any insight/advice to offer on what I may have done wrong or may be wrong? The system has not pulled any of the new fluid in.

 

[JWick]

Props to PADDO's AHC fluid replacement method!

I just had my AHC fluid replaced. My local indy shop quoted me over 3 hours labor. After reading many posts here that people were getting it done in an hour or less, I reached out to PADDO for advice. He provided me a step by step process that I gave to the local shop. They ended up following...

forum.ih8mud.com

This was the process I used and it worked perfectly, much simpler IMO too...assuming there is new fluid in the AHC reservoir so the system has something to draw back in? I apologize if this sounds like a basic question.

 

[blitt]

Thanks for sharing this link. There is new fluid in the reservoir. It’s full.

 

[blitt]

More Info: After retracing my steps, I realize now that I did skip a step on the procedure. I put the truck in Low and used a vacuum pump to pull all the old fluid out of the reservoir. I refilled the reservoir and went straight to bleeding the accumulator instead of starting the truck up and taking the AHC back to neautral. This may be where I've created an issue, but could anyone give me an idea of how to repair? Ive ordered a cable for Tech Stream to hopefully be able to gather more info.

 

[JWick]

More Info: After retracing my steps, I realize now that I did skip a step on the procedure. I put the truck in Low and used a vacuum pump to pull all the old fluid out of the reservoir. I refilled the reservoir and went straight to bleeding the accumulator instead of starting the truck up and taking the AHC back to neautral. This may be where I've created an issue, but could anyone give me an idea of how to repair? Ive ordered a cable for Tech Stream to hopefully be able to gather more info.

Seems like there is now probably air in the system and is most likely causing your issue. I would search the site how to purge the air and re-introduce the fluid back in. If all else fails, @PADDO is the guru.

 

[blitt]

More info:
Received cable last night and ran techstream. Had DTC C1762 Abnormal Oil Pressure for Pump. Cleared trouble code . Shut down the truck and restarted hoping suspension would work. No go

AHC OFF signal began flashing and received DTC1751 Continuous Currrent to Compressor Motor. Clered Trouble code and started truck again with now success.

Ran the active height test manually by shorting the diagnostic port under hood. Tried this a couple times (10 seconds at a time) and truck eventually lifted. Took for a test drive and about 1/4 mile down the road the AHC went back in to fail safe and dropped to low.

Before my attempt to flush the fluid, the whole system functioned perfectly. I had 8 graduations in the reservoir when testing.

Im staring to become more convinced that I have air in the system but the active test that is commonly used to bleed the system doesn't seem to be working. Is there an alternative method to bleed air out of this AHC system?

I also cracked open the hydraulic line coming out of the pump to check for flow and an did have flow and I can hear the pump running.

Another possibility I am considering is that there is sludge that concentrated at the bottom of the reservoir and is not allowing enough flow to the system, thus throwing the dtc1762. Is this a reasonable culprit? If so should I just drain the reservoir, remove it and clean it? is there just a screen down at the bottom before entering the pump?

thanks in Advance for any insight!

 

[Jigsaw100]

Is it currently sitting low? can you drive it just a tiny bit without hurting anything? I had an AHC problem that healed itself after a bit of driving. Sounds like air is in there. Are your accumulator globes shot?

 

[blitt]

It is currently sitting. I’ve driven it some but not more than 10-15 miles. I don’t think the globes are shot because I had 8 notches of difference before flushing.

 

[blitt]

Last night I removed the reservoir from the top of the pump. the strainer at the bottom was free and clear it doesn't appear that sludge has clogged that up.

Still hoping someone one might have an alternative method of bleeding air from the system outside of the normal active test method where you short the diagnostic port and press the down AHC button 5 times?

 

[Jigsaw100]

when you open the bleed ports on (near?) the globes what comes out? have you put a clear tube on it? When I bled mine i had to go around a few times until all the air was out and the tube was helpful to see if there were bubbles.

I also read somewhere that rocking it back and forth was helpful.

Good luck, I know these kind of problems are really awful to deal with.

 

[Jigsaw100]

also, since you can raise it, maybe raise it a just a bit. bleed it back down. and repeat a few times

 

[blitt]

I haven't tried to get air out of the bleed ports as I was concerned I might let more in. I'll give it a shot and see. Thanks Jigsaw!

 

[Jigsaw100]

Good luck! use a a couple feet of tubing running into a bottle of fluid to make it less likely to get air in...run that hose into bottle with some AHC fluid in it (just like a clear plastic coke bottle). What I did was crack the bleeder, let some fluid out which you can monitor coming down the tubing then close it again as the truck settles. Do this a few times and I hope you'll be back up and running.

 

[blitt]

Update: Removed the reservoir again and took it a few steps further by removing the motor/pump assembly. Disassembled the pump and found the screen that filters the suspension fluid to have a fine sediment or something. I took the pump apart and blasted with carb cleaner. Reassembled everything, put fluid back in, started the truck and immediately the pump started sucking fluid in and I could visibly see the fluid level in the reservoir dropping!?!?!? The truck did raise to low according to the indicator although it appeared to be at the same level as when fail safe mode kicked in. I bled back and forth from side to side a couple times. Also ran the active height test but the truck never would come up all the way to N. One thing I noticed is that the pump ran super quiet when it first started and was pulling fluid in, but after a minute or so it stopped taking in fluid and the pump got load again.

After I bled both sides of the truck a couple times, I was no longer able to get the truck to raise any. It seems im back to where I started. My question, does this tell anyone anything about the pump? Im not opposed to replacing the pump sub assembly but of course id rather not replace a $300 part if necessary.

 

[blitt]

SOLVED! - Well after weeks of reading forums and trying different things, I finally have the LC back on the road. For me the solution was replacing the pump sub-assembly just under the reservoir. This is a 2007 LC with AHC. The truck is new to us but has 200,000mi. The previous owner had never flushed the suspension fluid and I could not find any service records that it had been done prior to his ownership. When I went to do a flush of the system, I bled one side and then started the truck to let it level out but it would not raise. In the midst of my forum reading, I came across a Toyota Service Bulletin CP-3006 (search- "cp-3006 ih8mud"). The TSB was for 2003 & older vehicles but the troubleshooting steps were helpful to me and pointed to the pump sub-assembly. The bulletin covers replacement of the height accumulator but that was not necessary for my situation and I did not do that. I only replaced the pump sub assembly and two O-rings.

Prior to finding the solution my old pump was very noisy and would not take fluid in. it would try to run for a good amount of time then go into fail safe mode and kick a DTC C1762. Last night I installed the new pump sub-assembly in about 30 minutes, said a little prayer and fired up the truck. It immediately started pulling fluid in and runs very quietly. I've used the active height test to manually raise the vehicle and bleed air. I've also excercised the system between low and high several times (at the advise of the master mechanic at the local Lexus dealership). Also bled a little air from the bleed ports from side to side. Suspension seems to be performing like it should now.

Here are the parts I replaced:
48901-60010 Pump Sub-Assy
90301-70003 O-ring (big)
90301-06012 O-ring (small)
(credit Joe422 https://forum.ih8mud.com/threads/finally-fixed-my-ahc-changed-pump.287320/)

I found the pump for around $260 in the US and fluid from the local Lexus dealership was around $80

It's tough to say what was the exact problem, but the PO stated that every time he reached his destination he would drop the suspension to "Lo" so it could be that the pump was just very worn. Once I bled the system down to the bump stops or close on one side, it may have been too weak to raise it back up. I'm not exactly sure as this is my first experience with hydraulics. Either way, this was the solution that got us back on the road. Im very grateful for all the posts here on ih8mud. I'm on my second LC and it's untelling how much money this forum has saved us. Thanks!

I will say that the pump is not difficult to remove. All you need is a 10mm socket and or wrench. There are two bolts for the reservoir that have to come off first. The one on the right is accessed from the back and difficult to remove. A ratcheting wrench is helpful for this one. Everything else is easy to disassemble.