2002 LX470. 172,xxx miles. I've read all the threads about replacing the AHC globes, but I'm confused about the situation I'm in and not sure if it would actually solve my problem - hoping to get some insight from the brain trust before I go and start spending $400+ on parts.
AHC system worked well LO>M>HI until a recent trip I took up north where temps got down to -10f. Exact moment and cause of failure is not totally clear - the day I really noticed it wasn't performing I had lowered it into park in the evening before and my wife was the one who drove it in the morning. I didn't drive it again until later that day and I noticed the car was sitting low and the "off" warning was flashing on the dash for AHC. She didn't say there were any loud sounds or odd behavior, though she did say "the car was really rough over bumps now that you mention it"
Symptoms:
- stuck in LO
- DTC codes 1751 (continuous current to compressor) and 1762 (abnormal oil pressure for pump)
- pump runs. Signs of life in the rear (raises ever so slightly) but no motion in the front. Connecting to bootleg techstream confirms this.
- Ride is very firm/harsh, especially in the front. Springs/sway bars definitely seem to be taking the load, and it's not hard to push the car down onto the bump stops with my weight on each front corner. There's still a little bounce and plushness in the rear but not nearly as much as it had when AHC worked.
I bled each corner as a test to see if there was air and all immediately spat out clean & translucent (but light brown) fluid. Things took a turn when I bled the center accumulator - it was as dark as coffee and had chunks in it. See photo:
While seems obvious that all is not well with that center accumulator, what's throwing me for a loop is the pressure test results I'm getting from the bootleg techstream device (Launch) I'm using to test the system:
Accumulator pressure readings test 3/13/25 before doing any bleed testing: rear: 5.3mPa, front 0.0mPa, center 6.3mPa
Accumulator pressure readings test 3/15/25 after bleed testing and attempting to raise car to N: rear 5.8mPa, Front 4.4mPa, center 0.0mPa
FWIW I have a receipt from the previous owner showing AHC system maintenance in 2023 - he said all four globes were replaced. On the invoice cost of parts was $752 and labor $110 which seemed low for all four, but looking underneath at the car all four globes do look pretty new (the one pictured is representative of all of them). Center accumulator does not look as new.
so with all that context, here are my questions for those who have more experience:
- Given the color of that fluid, is my center accumulator toast? I'm confused by the inconsistent pressure readings
- Is it possible to have globe failures, even if the fluid comes out clean and clear when bleeding? (again, confused by inconsistent pressure readings)
- I read a thread or two from folks who spoke of needing to clean filters... I know there's one in the pump assembly in the engine bay, but is there also one in the center accumulator? Is it worth me attempting dissasembly/clean of filters before replacing center accumulator?
Thanks for any help offered!
AHC system worked well LO>M>HI until a recent trip I took up north where temps got down to -10f. Exact moment and cause of failure is not totally clear - the day I really noticed it wasn't performing I had lowered it into park in the evening before and my wife was the one who drove it in the morning. I didn't drive it again until later that day and I noticed the car was sitting low and the "off" warning was flashing on the dash for AHC. She didn't say there were any loud sounds or odd behavior, though she did say "the car was really rough over bumps now that you mention it"
Symptoms:
- stuck in LO
- DTC codes 1751 (continuous current to compressor) and 1762 (abnormal oil pressure for pump)
- pump runs. Signs of life in the rear (raises ever so slightly) but no motion in the front. Connecting to bootleg techstream confirms this.
- Ride is very firm/harsh, especially in the front. Springs/sway bars definitely seem to be taking the load, and it's not hard to push the car down onto the bump stops with my weight on each front corner. There's still a little bounce and plushness in the rear but not nearly as much as it had when AHC worked.
I bled each corner as a test to see if there was air and all immediately spat out clean & translucent (but light brown) fluid. Things took a turn when I bled the center accumulator - it was as dark as coffee and had chunks in it. See photo:
While seems obvious that all is not well with that center accumulator, what's throwing me for a loop is the pressure test results I'm getting from the bootleg techstream device (Launch) I'm using to test the system:
Accumulator pressure readings test 3/13/25 before doing any bleed testing: rear: 5.3mPa, front 0.0mPa, center 6.3mPa
Accumulator pressure readings test 3/15/25 after bleed testing and attempting to raise car to N: rear 5.8mPa, Front 4.4mPa, center 0.0mPa
FWIW I have a receipt from the previous owner showing AHC system maintenance in 2023 - he said all four globes were replaced. On the invoice cost of parts was $752 and labor $110 which seemed low for all four, but looking underneath at the car all four globes do look pretty new (the one pictured is representative of all of them). Center accumulator does not look as new.
so with all that context, here are my questions for those who have more experience:
- Given the color of that fluid, is my center accumulator toast? I'm confused by the inconsistent pressure readings
- Is it possible to have globe failures, even if the fluid comes out clean and clear when bleeding? (again, confused by inconsistent pressure readings)
- I read a thread or two from folks who spoke of needing to clean filters... I know there's one in the pump assembly in the engine bay, but is there also one in the center accumulator? Is it worth me attempting dissasembly/clean of filters before replacing center accumulator?
Thanks for any help offered!
