AHC pump out? With code 1762 (1 Viewer)

[suprarx7nut]

I have seen 1.x was able to program key, customize telescoping, door lock, window and sunroof settings.

The 1.x cable I own was able to program my key, disable my DRLs, and stop that annoying auto-telescope wheel from activating. I have a 01LX that doesn't have TPMS, and I have read multiple places that the V1.x cables don't allow TPMS manipulation.

I think for SURE the 200 series would benefit from the V2.x cable. On the Hundys, it is perhaps only a benefit for those folks with TPMS and maybe some more advanced key programming requirements?

Ah, ok, good info. This makes me think the 06-07s might be different then. With my 1.X cable I was able to program the customization features, but not able to "register" things like new keys or TPMS. With a 2.X firmware cable it all worked.

In that case, maybe the cable firmware 2.X is only meaningful for the 06+ crowd.

 

[BullElk]

It was the pump. I replaced with a good used pump and everything pumps up just fine. I can barely even hear the motor and pump. I took a few pics and plan to write up how I replaced the AHC motor/pump. When I get a laptop I plan to hook up Techstream and learn a little.

Thanks a whole lot for everyone's help especially 1sar39 for his generosity with supplying me with an excellent pump. I will be on the look out to see what I can pass on to another Mud Bud in need.

 

[1sar39]

Awesome! Glad to hear you got the pump installed and brought your AHC back to life.

 

[medtro]

It was the pump. I replaced with a good used pump and everything pumps up just fine. I can barely even hear the motor and pump. I took a few pics and plan to write up how I replaced the AHC motor/pump. When I get a laptop I plan to hook up Techstream and learn a little.

Thanks a whole lot for everyone's help especially 1sar39 for his generosity with supplying me with an excellent pump. I will be on the look out to see what I can pass on to another Mud Bud in need.

How many miles on the failed pump?

 

[BullElk]

How many miles on the failed pump?

2006 with 274k. I have a 2000 with 355k and never had any AHC issues at all.

 

[ramangain]

2006 with 274k. I have a 2000 with 355k and never had any AHC issues at all.

Thank your deity of choice

 

[BullElk]

Few pics of old pump with guts open. That jelly fluid is one year and 11 months old.

 

[ramangain]

Good example of why changing AHC fluid is necessary so that gunk doesn't build up like that.

I'd wager that is years of buildup, not just the stuff that built up since the most recent fluid change.

 

[IndroCruise]

Few pics of old pump with guts open. That jelly fluid is one year and 11 months old.

View attachment 2452451View attachment 2452452View attachment 2452454

Thank you @BullElk ! The very helpful but worrying pictures of accumulated ‘gloop’ made me wonder whether I had the same problem – or worse, whether a similar accumulation of ‘gloop’ was occurring elsewhere in the AHC system beyond the Pump -- such as the Return Valve, Attenuator, Control Valve Assembly, various solenoid valves, step motors and valves in the Damping Force Control Actuators (to which the ‘globes’ are attached) etc, etc.

I had already replaced my LC100 AHC Pump (whole pump-motor-tank assembly) and Height Control Accumulator with new Toyota/Lexus units. This was done in response to an occasional DTC 1751 and a persistent DTC 1762 with vehicle very slow to raise from “LO” to “N” – 30 to 40 seconds, and for long term reliability. [DTC 1751 = Pump and Motor Circuit; DTC 1762 = Fluid Pressure Abnormality].

For interest, I disassembled my old AHC Pump but found only very light accumulations of very fine dark material, similar to that seen on the inside of my AHC tank after 14 years, despite many AHC Fluid changes. These accumulations did not seem sufficient to be causing a problem. I recalled insights from @PADDO which were concerning the strainers within the AHC Pump at his post #16 and onwards in that thread.

I located these pressed-in strainers near the pump ports as shown by a ‘star’ in the following pictures but was unable to remove the strainers for close inspection. Blowing through the strainers did not suggest that they were obstructed.

A further search revealed a post concerning an AHC Pump on a LX570 by IH8MUD Member @Zel. The pictures of the LX570 AHC Pump itself looks very similar to the LC100/LX470 AHC Pump even though the rest of LX570 AHC system is very different. @Zel was seeking advice about replacement strainers (helpful pictures included) but received no replies.

The pictures below show my AHC Pump as disassembled and without cleaning. The component parts appear to be in excellent condition.

The pictures below are offered for interest as the internals of the AHC Pump are rarely seen.

The AHC Pump is a small, simple high pressure gear displacement pump and is well-described with diagrams at FSM reference: https://lc100e.github.io/manual/ (follow tabs starting at the top:
New Car Features > CHASSIS > Suspension > Active Height Control Suspension).

Sad to report – in my case even with a complete new AHC Pump assembly and a new Height Control Accumulator, the vehicle remains slow-to-raise from “LO” to “N” and DTC 1762 still persists – so I am missing the point somewhere! This will be the subject of a separate post seeking advice.

Meanwhile, any comments are very welcome ….

A series of pictures follows, spread across this post #69 and the next post #70:

AHC Pump Diagram From FSM

AHC Pump Cover Removed

Initial Disassembly

Gear Pump Exposed

Complete Disassembly

 

[IndroCruise]

Thank you @BullElk ! The very helpful but worrying pictures of accumulated ‘gloop’ made me wonder whether I had the same problem – or worse, whether a similar accumulation of ‘gloop’ was occurring elsewhere in the AHC system beyond the Pump -- such as the Return Valve, Attenuator, Control Valve Assembly, various solenoid valves, step motors and valves in the Damping Force Control Actuators (to which the ‘globes’ are attached) etc, etc.

I had already replaced my LC100 AHC Pump (whole pump-motor-tank assembly) and Height Control Accumulator with new Toyota/Lexus units. This was done in response to an occasional DTC 1751 and a persistent DTC 1762 with vehicle very slow to raise from “LO” to “N” – 30 to 40 seconds, and for long term reliability. [DTC 1751 = Pump and Motor Circuit; DTC 1762 = Fluid Pressure Abnormality].

For interest, I disassembled my old AHC Pump but found only very light accumulations of very fine dark material, similar to that seen on the inside of my AHC tank after 14 years, despite many AHC Fluid changes. These accumulations did not seem sufficient to be causing a problem. I recalled insights from @PADDO concerning the strainers within the AHC Pump concerning the strainers within the AHC Pump at his post #16 and onwards in that thread.

I located these pressed-in strainers near the pump ports as shown by a ‘star’ in the following pictures but was unable to remove the strainers for close inspection. Blowing through the strainers did not suggest that they were obstructed.

A further search revealed a post by IH8MUD Member @Zel concerning an AHC Pump on a LX570. The pictures of the LX570 AHC Pump itself looks very similar to the LC100/LX470 AHC Pump even though the rest of LX570 AHC system is very different. @Zel was seeking advice about replacement strainers (helpful pictures included) but received no replies.

The pictures below show my AHC Pump as disassembled and without cleaning. The component parts appear to be in excellent condition.

The pictures below are offered for interest as the internals of the AHC Pump are rarely seen.

The AHC Pump is a small, simple high pressure gear displacement pump and is well-described with diagrams at FSM reference: https://lc100e.github.io/manual/ (follow tabs starting at the top:
New Car Features > CHASSIS > Suspension > Active Height Control Suspension).

Sad to report – in my case even with a complete new AHC Pump assembly and a new Height Control Accumulator, the vehicle remains slow-to-raise from “LO” to “N” and DTC 1762 still persists – so I am missing the point somewhere! This will be the subject of a separate post seeking advice.

Meanwhile, any comments are very welcome ….

View attachment 2455878

View attachment 2455879

View attachment 2455880

View attachment 2455884

View attachment 2455887

Further pictures in the series started at my previous post #69 ....

Pump Inlet Port and Strainer Position

Pump Outlet Port Position

Pump Outlet Strainer Position

Pump Strainers (not removed by IndroCruise, picture by @Zel)

 

[aharlan001]

Anyone else want to donate a working old pump? I think mine is shot but I'm not sure.

 

[planomateo]

Great thread!

 

[parkeyjack]

Thank you @BullElk ! The very helpful but worrying pictures of accumulated ‘gloop’ made me wonder whether I had the same problem – or worse, whether a similar accumulation of ‘gloop’ was occurring elsewhere in the AHC system beyond the Pump -- such as the Return Valve, Attenuator, Control Valve Assembly, various solenoid valves, step motors and valves in the Damping Force Control Actuators (to which the ‘globes’ are attached) etc, etc.

I had already replaced my LC100 AHC Pump (whole pump-motor-tank assembly) and Height Control Accumulator with new Toyota/Lexus units. This was done in response to an occasional DTC 1751 and a persistent DTC 1762 with vehicle very slow to raise from “LO” to “N” – 30 to 40 seconds, and for long term reliability. [DTC 1751 = Pump and Motor Circuit; DTC 1762 = Fluid Pressure Abnormality].

For interest, I disassembled my old AHC Pump but found only very light accumulations of very fine dark material, similar to that seen on the inside of my AHC tank after 14 years, despite many AHC Fluid changes. These accumulations did not seem sufficient to be causing a problem. I recalled insights from @PADDO which were concerning the strainers within the AHC Pump at his post #16 and onwards in that thread.

I located these pressed-in strainers near the pump ports as shown by a ‘star’ in the following pictures but was unable to remove the strainers for close inspection. Blowing through the strainers did not suggest that they were obstructed.

A further search revealed a post concerning an AHC Pump on a LX570 by IH8MUD Member @Zel. The pictures of the LX570 AHC Pump itself looks very similar to the LC100/LX470 AHC Pump even though the rest of LX570 AHC system is very different. @Zel was seeking advice about replacement strainers (helpful pictures included) but received no replies.

The pictures below show my AHC Pump as disassembled and without cleaning. The component parts appear to be in excellent condition.

The pictures below are offered for interest as the internals of the AHC Pump are rarely seen.

The AHC Pump is a small, simple high pressure gear displacement pump and is well-described with diagrams at FSM reference: https://lc100e.github.io/manual/ (follow tabs starting at the top:
New Car Features > CHASSIS > Suspension > Active Height Control Suspension).

Sad to report – in my case even with a complete new AHC Pump assembly and a new Height Control Accumulator, the vehicle remains slow-to-raise from “LO” to “N” and DTC 1762 still persists – so I am missing the point somewhere! This will be the subject of a separate post seeking advice.

Meanwhile, any comments are very welcome ….

A series of pictures follows, spread across this post #69 and the next post #70:

AHC Pump Diagram From FSM
View attachment 2455878

AHC Pump Cover Removed
View attachment 2455879

Initial Disassembly
View attachment 2455880

Gear Pump Exposed
View attachment 2455884

Complete Disassembly
View attachment 2455887

Indro! Did you figure out what the culprit could be for the slooooow raise times? Mine is in the same boat. Thinking could be air in the system? Did you do active test after you put the new pump on to force some of the air down the lines?

 

[IndroCruise]

Indro! Did you figure out what the culprit could be for the slooooow raise times? Mine is in the same boat. Thinking could be air in the system? Did you do active test after you put the new pump on to force some of the air down the lines?

Sad to say, I still have not closed out this job with the necessary steps posted here. Next week, we were due to travel from home in Brisbane on the East coast of Australia to Perth on the West coast of Australia -- similar road distance as New York to Los Angeles. The vehicle is now located in Perth in the hands of my daughter and son-in-law -- who are not yet 'AHC-trained'! Meanwhile the Western Australian State Government (Perth is the State Capital) is holding fast on COVID Border Controls and quarantine arrangements, so we are delayed yet again!! When I finally get there, the review will be methodical as described at the above link. However, so much of the AHC system on this vehicle has new OEM replacement parts – four ‘globes’, AHC Pump, three Height Control Sensors, Height Control Accumulator, two Front Shock Absorbers, but no issues nor replacements of the original Rear Shock Absorbers nor of the original Damping Force Control Actuators nor the ECU nor associated relays and fuses.

So my primary suspicions really are air still in the system, and/or, improperly adjusted Height Control Sensors causing slow ECU response.

If the AHC Pump was not new, I certainly would suspect blocked internal strainers and reduced pump delivery pressure and flow. Maybe I have to check the new Pump anyway!

The vehicle has a few additions – ARB Deluxe Bar, Toyota tow-bar, Kaymar Rear Wheel Holder for additional spare wheel – but it is not particularly heavy. Weighbridge says 2,920 kilograms (6,437 pounds) with 141 litres = 37 US gallons of diesel fuel in tanks, no people on board, no other load – but 1HD-FTE turbodiesel is at least 120 kilograms (265 pounds) heavier than 2UZ-FE. Whatever, the vehicle weight is well within the FSM guidance on AHC weight limits but is much heavier than the stock kerb weight – so there will be some slowing effect on raise times. I don’t think weight is the whole story.

The vehicle also has Firestone Coilrite airbags inside the KING KTRS-79 Rear coil springs. It has been suggested that friction between the airbags and their Kevlar covers and the coil springs also will have slowing effect on raise times – possible – but I don’t think that is the whole story either.

So I think for me it is “back to AHC basics” – I will report further when I finally get that done.

Previous AHC Fluid changes were done twice by my independent mechanic when doing other work. He is a good man but I know he was in a rush at those times and for my own satisfaction I would like to bleed the system myself.

The PADDO Method for bleeding is excellent but when there are ongoing suspected residual air problems, I favour multiple bleed cycles from all five (5) bleeders including movements “N” to “HI” to “N” to “LO” to cause the Height Control Accumulator to discharge and recharge multiple times and to cause the AHC Fluid in the ‘globes’ and in the Shock Absorbers to empty and refill as far as possible multiple times. These never are completely ‘flushed’ because there is no ‘through’ path for the fluid – for example it moves in and out of the Shock Absorbers, not through the Shock Absorbers from one end to the other, and there always is some ‘unswept’ volume at the bottom of the Shock Absorbers. The solenoid valve at the Height Control Accumulator is normally closed, only opens on two occasions: (1) when releasing fluid to raise the vehicle “LO” to “N” or “N” to “HI”, and, (2) when the AHC Pump recharges the Accumulator with fluid after a raise has completed. When nothing comes out of the Accumulator when bleeding, it is because it has not been recharged and there is nothing in there -- assuming no other problems such as faulty solenoid or the system being in one or other of the 'fail safe' modes due to other faults.

I do use the “Active Test” at Page 6 of the attachment – with a paperclip bridging Ts and E1 in DLC1 in the engine bay, easier than using DLC3 under the dash as shown in some FSM versions -- to ensure that the AHC Pump is primed and to push fluid into the system. This helps but by itself will not ‘flush’ the system. The vital thing is raising and lowering the vehicle as part of each bleeding cycle, so as to get as much affected fluid and residual air out of the system as possible, being careful to shut off bleeders during outflow so as not to draw in any air.

This has turned into another rambling post – but maybe it will give you a few thought starters.

 

[parkeyjack]

Sad to say, I still have not closed out this job with the necessary steps posted here. Next week, we were due to travel from home in Brisbane on the East coast of Australia to Perth on the West coast of Australia -- similar road distance as New York to Los Angeles. The vehicle is now located in Perth in the hands of my daughter and son-in-law -- who are not yet 'AHC-trained'! Meanwhile the Western Australian State Government (Perth is the State Capital) is holding fast on COVID Border Controls and quarantine arrangements, so we are delayed yet again!! When I finally get there, the review will be methodical as described at the above link. However, so much of the AHC system on this vehicle has new OEM replacement parts – four ‘globes’, AHC Pump, three Height Control Sensors, Height Control Accumulator, two Front Shock Absorbers, but no issues nor replacements of the original Rear Shock Absorbers nor of the original Damping Force Control Actuators nor the ECU nor associated relays and fuses.

So my primary suspicions really are air still in the system, and/or, improperly adjusted Height Control Sensors causing slow ECU response.

If the AHC Pump was not new, I certainly would suspect blocked internal strainers and reduced pump delivery pressure and flow. Maybe I have to check the new Pump anyway!

The vehicle has a few additions – ARB Deluxe Bar, Toyota tow-bar, Kaymar Rear Wheel Holder for additional spare wheel – but it is not particularly heavy. Weighbridge says 2,920 kilograms (6,437 pounds) with 141 litres = 37 US gallons of diesel fuel in tanks, no people on board, no other load – but 1HD-FTE turbodiesel is at least 120 kilograms (265 pounds) heavier than 2UZ-FE. Whatever, the vehicle weight is well within the FSM guidance on AHC weight limits but is much heavier than the stock kerb weight – so there will be some slowing effect on raise times. I don’t think weight is the whole story.

The vehicle also has Firestone Coilrite airbags inside the KING KTRS-79 Rear coil springs. It has been suggested that friction between the airbags and their Kevlar covers and the coil springs also will have slowing effect on raise times – possible – but I don’t think that is the whole story either.

So I think for me it is “back to AHC basics” – I will report further when I finally get that done.

Previous AHC Fluid changes were done twice by my independent mechanic when doing other work. He is a good man but I know he was in a rush at those times and for my own satisfaction I would like to bleed the system myself.

The PADDO Method for bleeding is excellent but when there are ongoing suspected residual air problems, I favour multiple bleed cycles from all five (5) bleeders including movements “N” to “HI” to “N” to “LO” to cause the Height Control Accumulator to discharge and recharge multiple times and to cause the AHC Fluid in the ‘globes’ and in the Shock Absorbers to empty and refill as far as possible multiple times. These never are completely ‘flushed’ because there is no ‘through’ path for the fluid – for example it moves in and out of the Shock Absorbers, not through the Shock Absorbers from one end to the other, and there always is some ‘unswept’ volume at the bottom of the Shock Absorbers. The solenoid valve at the Height Control Accumulator is normally closed, only opens on two occasions: (1) when releasing fluid to raise the vehicle “LO” to “N” or “N” to “HI”, and, (2) when the AHC Pump recharges the Accumulator with fluid after a raise has completed. When nothing comes out of the Accumulator when bleeding, it is because it has not been recharged and there is nothing in there -- assuming no other problems such as faulty solenoid or the system being in one or other of the 'fail safe' modes due to other faults.

I do use the “Active Test” at Page 6 of the attachment – with a paperclip bridging Ts and E1 in DLC1 in the engine bay, easier than using DLC3 under the dash as shown in some FSM versions -- to ensure that the AHC Pump is primed and to push fluid into the system. This helps but by itself will not ‘flush’ the system. The vital thing is raising and lowering the vehicle as part of each bleeding cycle, so as to get as much affected fluid and residual air out of the system as possible, being careful to shut off bleeders during outflow so as not to draw in any air.

This has turned into another rambling post – but maybe it will give you a few thought starters.

Yeah buddy. I feel your pain. I too have all new globes. King springs. Drained multiple times. Did the active test. Drained again. Good news ( I think ) is I just picked up two take off pumps from LX 470 for 150.00 bucks for both shipped. Going to switch out pumps and see if that doesn’t help! If not. I will switch out with another pump. Lol. Is your pump loud? Mine is very loud compared to another LC with AHC.

 

[BullElk]

Mine is very loud compared to another LC with AHC.

Loud is not good. May be clogged up with jelly goop like mine was. Should run very quiet when clean and proper.

 

[suprarx7nut]

Yeah buddy. I feel your pain. I too have all new globes. King springs. Drained multiple times. Did the active test. Drained again. Good news ( I think ) is I just picked up two take off pumps from LX 470 for 150.00 bucks for both shipped. Going to switch out pumps and see if that doesn’t help! If not. I will switch out with another pump. Lol. Is your pump loud? Mine is very loud compared to another LC with AHC.

Loud is not good. May be clogged up with jelly goop like mine was. Should run very quiet when clean and proper.

Yup, agreed. If your pump is loud I'd put money on the screens being full of gelatinous slime or somehow sucking in air. New pump or clearing out the screens and new o-rings are good options.

 

[IndroCruise]

Yup, agreed. If your pump is loud I'd put money on the screens being full of gelatinous slime or somehow sucking in air. New pump or clearing out the screens and new o-rings are good options.

Agree with @BullElk and @suprarx7nut.

Clogged strainers in the AHC Pump is likely to cause cavitation, typically means pump cannot get enough fluid, vapour bubbles form on suction side, bubbles then collapse on discharge side, pump makes a harsh sound, sometimes described as a rattling kind of sound. Frothy fluid also is a likely a consequence.

Many hydraulic pumps – including the AHC Pump -- have two strainers: one strainer on the inlet side to catch incoming debris, jelly-like stuff in hydraulic fluid (which also may be a consequence of cavitation), etc, etc – and one strainer on the outlet side, typically intended to catch debris passing through the pump or caused by cavitation which can include metal lifted from pump surfaces. This debris is not wanted elsewhere in the system, especially in AHC system in the fine passageways and valves in the Control Valve Assembly and in the Damping Force Control Activators.

Noise in pumps need investigation. Either the strainers and the pump should disassembled and cleaned as described in earlier posts in this thread and other AHC Pump threads – or the Pump should be replaced.

Sadly, the FSM provides little detail beyond a general description about the internals of the AHC Pump. Instead, the diagnostic sections recommend replacement when Pump performance is unsatisfactory – possibly because the designers (probably a Toyota/Lexus supplier) and/or the Toyota/Lexus FSM writers know that a blocked and noisy pump may be worn from cavitation and/or other debris, and maybe not be worth workshop repair. This need not dissuade a DIY owner from having a look inside the AHC Pump.

There is lots of stuff on the internet -- and in the minds of hydraulic specialists -- about cavitation (and the slightly different condition of aeration) in hydraulic pumps. Here is a short video:

 

[parkeyjack]

Agree with @BullElk and @suprarx7nut.

Clogged strainers in the AHC Pump is likely to cause cavitation, typically means pump cannot get enough fluid, vapour bubbles form on suction side, bubbles then collapse on discharge side, pump makes a harsh sound, sometimes described as a rattling kind of sound. Frothy fluid also is a likely a consequence.

Many hydraulic pumps – including the AHC Pump -- have two strainers: one strainer on the inlet side to catch incoming debris, jelly-like stuff in hydraulic fluid (which also may be a consequence of cavitation), etc, etc – and one strainer on the outlet side, typically intended to catch debris passing through the pump or caused by cavitation which can include metal lifted from pump surfaces. This debris is not wanted elsewhere in the system, especially in AHC system in the fine passageways and valves in the Control Valve Assembly and in the Damping Force Control Activators.

Noise in pumps need investigation. Either the strainers and the pump should disassembled and cleaned as described in earlier posts in this thread and other AHC Pump threads – or the Pump should be replaced.

Sadly, the FSM provides little detail beyond a general description about the internals of the AHC Pump. Instead, the diagnostic sections recommend replacement when Pump performance is unsatisfactory – possibly because the designers (probably a Toyota/Lexus supplier) and/or the Toyota/Lexus FSM writers know that a blocked and noisy pump may be worn from cavitation and/or other debris, and maybe not be worth workshop repair. This need not dissuade a DIY owner from having a look inside the AHC Pump.

There is lots of stuff on the internet -- and in the minds of hydraulic specialists -- about cavitation (and the slightly different condition of aeration) in hydraulic pumps. Here is a short video:

Yeah. I already opened up the pump and all looked well. No jelly or anything. I have got two used entire pumps coming to me tomorrow in the mail. Guy took them off his truck and his dads truck. Look to be in excellent condition. Going to try swapping out and seeing if this fixes the problem!

 

[parkeyjack]

Yeah. I already opened up the pump and all looked well. No jelly or anything. I have got two used entire pumps coming to me tomorrow in the mail. Guy took them off his truck and his dads truck. Look to be in excellent condition. Going to try swapping out and seeing if this fixes the problem!

Well. Got the pumps in. And they look to be in good condition. Went to take off my whole pump and stripped the dagum feed line to the pump…soooo I said, “pump assembly is staying there for right now.”
Well I changed out the little pump with the good one the guy said there was no problems with. Nothing. Blinking off light. Tried active test. Nothing. So. Put in the second pump. Same freaking thing. Finally put back in my old pump and got it working again.

Still. Raise times are in 30 seconds.

After closer inspection you can see all three pump mechanisms have a small indentation in three completely different places. I assume this is why the pump would not work.

***Side note*** Is there anyway I can take one of the old fittings off the old pump and put it on my feed line…? And yes, I will be purchasing some flare wrenches in the future. To keep this from happening again.