I know we have 39 page AHC basics but I haven't seen too many threads on AHC failures so figure I will consolidate my issues here since looks like my system is pretty beat up.
In 2016, I made a mistake of buying a fairly rusty LX570 in Northern NJ. It was 2011 LX570 with 68k miles and has been driven a lot during bad winters up here (or just parked in an ocean for a while)
In 2017, I had fluid pouring down during one of my trips. Nice! Freaked me out a bit as I didn't know what it might lead to driving like that. I was fine. Car goes into low mode, shocks basically don't work so ride sucks, but car drives ok. I probably drove 100miles like this with a 4000lbs trailer.
I acutally use AHC a lot when I load/unload race car unto a trailer. It's super useful feature to angle the trailer by raising LX up and lowering to hook/unhook the trailer. I also use comfort access to so my AHC is used constantly.
So in 2017, 3 AHC lines running from the pump to the accumulator were replaced. They were 48997-60010, 48998-60010 and 48999-60010.
In 2021, I got around to flushing the system myself and there was definitely some air in the system in one of the accumulators. I haven't noticed any improvement after the flush but I didn't have issues either.
In 2023, on my was to Watkins Glen, "Check AHC" comes on and the ride get rough. I drove about 200miles there and 250miles back with the trailer and another 150 miles after that between my garage and dealer. My LX also left me completely stranted a few month before and would not start once during this trip, but that's separate non-AHC realted stories. Let's say I was ready to go buy a new seqouia, but you just can't and I'm not paying over MSRP for an already overpriced car that's arguably worse than my 12 year old LX.
Dealer was completely useless quoting 13k to fix the issue, consisting of new pump and 4 valve control units. I politely declined this generous offer.
Icarsoft gave me C1763 code (abnormal pressure at the pump), which is basically due to either a leak, failed pump or failed AHC ECU.
I didn't see any leaks, as the lines by the pump are all fairly new. Interstingly, the frame near the pump does have wetness around, but a kind that accumulates over time with some dirt. I assume perhaps that's coming from the breather hoses.
Pump is very easy to test. You unplug it and connect directly to any 12V battery and see if it works. Mine does absolutely nothing (you gotta be careful, as it's a high pressure pump). Mine also looks absolutely disgusting. A little bit of a better insulation would have gone big way.
Pump pricing is very interesting....dealer quote was 3200 (just for he part, price from online dealers is 2300, price on ebay from international sellers is about 1k. I just bought one from japan. It arrived in a week. Looks brand new in a box with toyota part number.
Removing old pump took maybe 2 hours because I was taking my time and didn't want to snap bleader valve on the main accumulator in order to release pressure.
Removal of the pump consistst of removing a few rear splash guards and 3 bolts that hold the tray with the pump. Then just undo the high pressure line and the breather hoses bracket. Taking spare tire out makes for ample access especially if you have access to a lift.
Updates to come.
Another project is replacing the alternator without touching the exhaust.
In 2016, I made a mistake of buying a fairly rusty LX570 in Northern NJ. It was 2011 LX570 with 68k miles and has been driven a lot during bad winters up here (or just parked in an ocean for a while)
In 2017, I had fluid pouring down during one of my trips. Nice! Freaked me out a bit as I didn't know what it might lead to driving like that. I was fine. Car goes into low mode, shocks basically don't work so ride sucks, but car drives ok. I probably drove 100miles like this with a 4000lbs trailer.
I acutally use AHC a lot when I load/unload race car unto a trailer. It's super useful feature to angle the trailer by raising LX up and lowering to hook/unhook the trailer. I also use comfort access to so my AHC is used constantly.
So in 2017, 3 AHC lines running from the pump to the accumulator were replaced. They were 48997-60010, 48998-60010 and 48999-60010.
In 2021, I got around to flushing the system myself and there was definitely some air in the system in one of the accumulators. I haven't noticed any improvement after the flush but I didn't have issues either.
In 2023, on my was to Watkins Glen, "Check AHC" comes on and the ride get rough. I drove about 200miles there and 250miles back with the trailer and another 150 miles after that between my garage and dealer. My LX also left me completely stranted a few month before and would not start once during this trip, but that's separate non-AHC realted stories. Let's say I was ready to go buy a new seqouia, but you just can't and I'm not paying over MSRP for an already overpriced car that's arguably worse than my 12 year old LX.
Dealer was completely useless quoting 13k to fix the issue, consisting of new pump and 4 valve control units. I politely declined this generous offer.
Icarsoft gave me C1763 code (abnormal pressure at the pump), which is basically due to either a leak, failed pump or failed AHC ECU.
I didn't see any leaks, as the lines by the pump are all fairly new. Interstingly, the frame near the pump does have wetness around, but a kind that accumulates over time with some dirt. I assume perhaps that's coming from the breather hoses.
Pump is very easy to test. You unplug it and connect directly to any 12V battery and see if it works. Mine does absolutely nothing (you gotta be careful, as it's a high pressure pump). Mine also looks absolutely disgusting. A little bit of a better insulation would have gone big way.
Pump pricing is very interesting....dealer quote was 3200 (just for he part, price from online dealers is 2300, price on ebay from international sellers is about 1k. I just bought one from japan. It arrived in a week. Looks brand new in a box with toyota part number.
Removing old pump took maybe 2 hours because I was taking my time and didn't want to snap bleader valve on the main accumulator in order to release pressure.
Removal of the pump consistst of removing a few rear splash guards and 3 bolts that hold the tray with the pump. Then just undo the high pressure line and the breather hoses bracket. Taking spare tire out makes for ample access especially if you have access to a lift.
Updates to come.
Another project is replacing the alternator without touching the exhaust.
