There is couple discussions in 200 forum about issues after ahc flush.
there is a batch of bad AHC fluid being sold by dealers. Fluid has some contamination gello like stuff plugging pumps and filters
Some pictures of the problematic internal strainers/screens (not to be confused with the strainer at the AHC Tank) are found in #Post 70 in this thread:
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...
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Go back to Post #69 in the same thread for further pictures of the pump internals and also a diagram and description of the nature of the pump taken from the FSM.
Previously,
@PADDO made observations at Posts #16 and #19 in a different thread:
I hooked my 2002 LX470 with 80K miles up to techstream yesterday to see what my neutral pressure readings were after replacing my globes. I was only getting like 6 graduations from the old globes and my front suspension felt like it was stuck in sport mode. After replacing the globes I have...
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He noted that:
“The two screens are internal to the pump so the pump/reservoir assembly needs to be removed from the vehicle. It’s then a matter of taking off the circular external pump housing which gives access to the pump. It’s retained to the main body and held together, its a sandwich design, by four cap screws. Undo the screws, and disassemble the pump sandwich and the screens are revealed. They are pressed in and can be cleaned in situ with a blast of 100% hydrocarbon cleaner or you can back them out with a pick to clean. Reassemble, install the pump/reservoir fill with fluid and let it sit for a while to assist the fluid in working it’s way into the pump housing/intake and fire it up. If it times out because it’s airlocked and can’t prime then force run it manually*”.
* means operation of the pump by “Active Test” for about 10 seconds with AHC fluid at correct level or better in the tank, or operation by direct connection to the battery.
Note that the strainers/screens are located on the input and output sides of the tiny gears (smaller than a thumbnail) which provide the actual pumping action. Gear pumps usually are specified for high pressure / low volume applications where the fluid is free of particulates. The strainers/screens are intended to keep particulates out of the actual pump. Particulates might otherwise degrade or destroy the gear action.
When an AHC Pump is thought to have failed or a relevant DTC such as C1762 is recorded – meaning that pump has power at the motor and rotates but the pressure is weak and AHC response is slow – then this is more likely to be caused by clogged strainers/screens than problems in the actual pump, unless the screens are missing or have holes which allow particles to pass into the gears. The pump is small but fit for purpose -- it would take something like a stream of sand to destroy the pump.
It is a judgement call whether to disassemble the actual pump and inspect and clean as described by
@PADDO, or, replace the pump sub-unit (Part Number 48901-60010 – current Partsouq price USD165.31 plus delivery). For peace of mind, replacing the pump sub-unit every 15 to 20 years may not be such a bad idea – especially where long term neglect (infrequent AHC fluid changes and infrequent AHC pressure checks) by previous owners is suspected. If using a secondhand pump, suggest disassemble and clean the strainers/screens before installation of the pump in the vehicle.
Unless it is desired to renew other associated components or unless there is a very conservative view about reliability, it should not be necessary to replace the whole assembly consisting of pump/motor/tank/pressure sensor/temperature sensor/housing with Return Valve, etc (Part Number 48910-60012 – current Partsouq price USD1,237.34 plus delivery).
Suggest if disassembling the pump to clean the internal screens/strainers, either leave the tiny gears and their carriers in place, or, carefully mark and photograph their orientation to one another so that they can go back together with all parts in the same place and gears meshing in exactly the same way. Ideally, replace all o-rings encountered and also the oil seal between the pump and the motor.
Step by step guidance with pictures on removal of the pump assembly can be found here:
This is an attempt to explain how I removed and replaced the AHC pump with a few pictures to help. Tools needed are... --10 mm deep socket (for bolt under reservoir) --10mm wrench --10mm crowfoot or small 10mm ratchet would be gold for other bolt holding reservoir --fluid extractor hose and...
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There are extensive but confusing discussions on IH8MUD “200 series Cruisers” concerning possible problems with some AHC Fluid supplies in USA but not sure whether the problem is real. In 2020 and 2021, I have bought genuine Toyota/Lexus AHC Fluid in 2.5 litre drums from Australian Toyota/Lexus dealers (fluid made by Japanese oil company Idemitsu Kosan Co., Ltd) and not had any problems. Suggest check information with local dealers about whether there is fake supply in circulation and insist on receiving the genuine stuff, no substitutes.
