My '03 LX AHC works great in all 3 modes on the front end but not on the rear. HI mode works on rear, N and LO seem to bottom out and run on the bump stops. Any ideas?
AHC rear end issues (1 Viewer)
- Thread starter twocircles
- Start date
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Springs are probably worn out. Miles? You got weight back there? Give a little more detail and more help will come through.
If you camp or carry a load frequently, upgrade to the King Springs, worth it if you keep the AHC. Do some reading here on them.
If you camp or carry a load frequently, upgrade to the King Springs, worth it if you keep the AHC. Do some reading here on them.
- Thread starter
- #3
150,000 miles, previous owner towed a boat, as soon as it comes out of HI it bottoms out and the rear end pogo's down the road at all speeds.
You may have a blown globe. I had the pogo effect as well on the front end. Once the globes were replaced the pogoing stopped.
How can you actually tell you have a blown globe? Unfortunately no easy way without removal.
Bleed out the fluid to the bump-stops , remove them from the accumulators/actuators (kinda a PITA w/o the right tools based on the tight space). A blown globe will have a large amount of fluid in it. It is very noticeable when comparing to non blown globes.
Good luck
I am selling a set I can't use anymore (long story) :
For Sale - AHC Components from a 2003 LX470 (110K)
How can you actually tell you have a blown globe? Unfortunately no easy way without removal.
Bleed out the fluid to the bump-stops , remove them from the accumulators/actuators (kinda a PITA w/o the right tools based on the tight space). A blown globe will have a large amount of fluid in it. It is very noticeable when comparing to non blown globes.
Good luck
I am selling a set I can't use anymore (long story) :
For Sale - AHC Components from a 2003 LX470 (110K)
- Thread starter
- #5
Do you still think it would work in HI if the globes were blown?
Yes, effectively you lost all dampening on one or more of the rear globes.
Each globe has a nitrogen filled membrane if ruptured you simply displace the membranes volume with more ahc fluid. This will still allow it to go into high but you lose all dampening that the membrane provided.
This is why you can identify the blown globe once it's removed because it just contains a large amount of ahc fluid compared to a non blown unit.
You can also do a gradient check from low to high on the ahc reservoir. I was at 7 gradients with a blown unit and went to 15+ once repaired.
Each globe has a nitrogen filled membrane if ruptured you simply displace the membranes volume with more ahc fluid. This will still allow it to go into high but you lose all dampening that the membrane provided.
This is why you can identify the blown globe once it's removed because it just contains a large amount of ahc fluid compared to a non blown unit.
You can also do a gradient check from low to high on the ahc reservoir. I was at 7 gradients with a blown unit and went to 15+ once repaired.
- Thread starter
- #7
Thanx, i'll have to look in to that gradient check. Unless you have a simple explanation on the procedure.
mark your reservoir where the fluid level is at hi mode, then lower low and count the marks on the reservoir (the range from low to hi or vis versa)
they say anything over 7 marks is still acceptable... but their are countless threads on here about ahc maintenance...
they say anything over 7 marks is still acceptable... but their are countless threads on here about ahc maintenance...
Sounds like a height control problem - probably rear sensor. If you post some actual vehicle front and rear heights in L,N and H that’ll help. Blown or flat globes have no affect on the vehicle maintaining its N height, they just affect damping, as does riding on the rear bump stops if you’ve got a failed rear sensor/linkage.
very good point PADDO, i hadn't considered that perspective... from the description i was assuming maybe he meant it felt like he was on the bump stops but i see your point, sounds very plausable
- Thread starter
- #12
So I did the HI LO test and the fluid went up and down about 13-14 marks on the reservoir. It still has the same issue. One time only after it was in HI the rear end dropped down about an inch. Could this be a glitchy height sensor that's causing this?
- Thread starter
- #14
Ride height measurements as requested. Keep in mind that I was only able to get it to work in all 3 modes 3 or 4 times, I did cycle it thru L, N and H about 12 times. I measured from the ground to the crease in the fender well directly above the tire. When It did work the measurements were in LO...….32.25" front and 32.25" rear, N...…..34" front and 35.25" rear, HI 35.50" front and 37" rear
Thanks, what I was looking for was some sort of consistent system behavior and you’ve seemed to confirm the rear height control is functioning pretty randomly, 3 out of 12 expected results, which implicates a rear height sensor that’s dead but doesn’t quite know it yet. I’d change that sucker out.
Similar issue, rear end is a pogo stick in n and l but works perfect in h, fluid, globes, springs are all good and under 2k miles on em, new rear height sensor did nothing, ahc fails 16 step test in rear only in l and n modes but passes in h
- Thread starter
- #17
Sorry to bother you PADDO,
Unrelated to the AHC issue that I had a year ago or so, I have a question about the VSC TRAC and VSC OFF lights on the dash. Both are on AFTER i had new tires installed AND an alignment done. They only come on after i start to drive. If i turn the ignition off, start the truck back up, the lights don't come on again until i start driving.
Here's the question........ I've heard/read on numerous pages that i can jumper 2 of the terminals in the DLC3 so that these lights will turn off. If true, which 2 terminal's are they? I've seen (Ts and CG) and also (Tc and CG). What are your thoughts?
2003 LX470
thank you
