Won't any MOBD code reader pull the DTCs? Let's start with that and then address what we can via DTC based resolution.
I'm glad to see that you have go the pump primed and working, that is usually the biggest issue. Please do add some detail on what you did for the pump and micro filter cleaning, we've been looking for more beta on how to do this succesfully . . .
Tell us about what bleeding and fluid replacement you have performed already.
Thank you for your reply #grinchy.
OK, in response to #grinchy request I have written out the whole AHC pump disassembly, cleanse and rebuild.
It was surprisingly easier to get to the dissembled stage than I had anticipated, but alas I did make a few mistakes, the biggest one was not taking photographs of each stage and not carefully marking each component to ensure they were replaced precisely and exactly from where they had been removed.
As regards the photographs I will indicate where #indrocruise has kindly provided a small catalogue of photographs for forum members benefit.
May I just thank Indrocruise once again for these photographs and all the other hello and guidance he has given me.
Please find photographs on
Definitive List of AHC maintenance items;
and go to #Indrocruise#943 item or post no #943.
In particular as IndroCruise highlighted the gear wheels would of most certainly been better removed by somehow marking them so as they could be replaced with the exact same teeth and gears meshing with each other, tooth by tooth. I will admit I did study them but for the life of me I could not think of a way to mark them that would not possibly interfere with the precision environment in which they must work. So I confess I omitted to mark my gear wheels in this case.
However, I had to keep on moving despite these anomalies.
To my great pleasure I found quite a considerable volume of sludge inside the the pump housing End Cap. It is The End cap with 3 screw hole or fixing points and the large “Cross or plus sign on it”.
The AHC oil temperature sensor is attached to this cap.
To my utter surprise and to be honest, delight, I found there was approximately half of an egg cup full of sludge inside this End Cap.
I used rubber gloves throughout this whole disassemble and reassemble process, continuously jetting the rubber gloves with the aerosol carbon cleaner to ensure the gloves were kept spotless.
I cleaned all components thoroughly before progressing on to disassembling the actual primary pump mechanism itself, the small module that holds the two gear wheels. I will call this assembly The Primary Pump Assembly.
Each and every part was washed and cleaned thoroughly.
Please forgive my crude methods but I found that using a spray can of aerosol carbon cleaner, a small metal pick and a tooth brush to spray and clean each component to a pristine shine.
I then embarked upon getting the two small filters removed. This was quite a job but boy was I glad I persevered.
May I at this stage once again thank Indrocruise for providing an extensive library of photographs and his detailed description of the pump being taken apart stage by stage.
May I also apologise for not taking photographs as I went through this process. I note how you professional contributors make great use of both photographs and video.
I will endeavour to progress to the use of photographs soon.
However These pictures supplied by Indrocruise are of immense help to anyone contemplating taking on this job.
These pictures are also extremely useful in understanding the following observations and suggestions as regards to rebuilding the AHC pump.
Now back to the Pump filters;
I tried quite a few methods to withdraw them from the housing, initially without success, in the end however I found that using a perfect fitting wood screw was a perfect solution.
I ground off the point of the screw to prevent it from damaging the very small and very fine mesh of the filter.
I screwed the screw in very tentatively making sure not to go too far (thus avoiding jamming the filter) and when I judged the screw had sufficient grip I extracted the screw and filter by mocking up a direct lift cantilever type affair that lifted the screw in a directly straight upwards trojectory. Once I got the “tensions” all as near as I could gauge this actually worked very well.
Now I have read in a few posts that some folk have suggested that due to the difficulty of extraction of these very petite and fragile filters, that they opted to not take them out but alternatively they jetted hydrocarbon cleaning fluid both directions from the inlet and outlet orifices.
I fully understand this decision, but upon my findings I don’t agree with trying to clean this way.
This was because I found it was very difficult to clean the small meshes in these petite filters when I had them totally removed from there enclosures never mind attempting to do so by simply blowing from either end of the enclosure.
I found that the debris which was a very fine sand like material was almost embedded like concrete inside the small mesh and to make it even more difficult these small meshes have small overlaps of mesh (via their manufacturing process) that must be gently manipulated by squeezing between your fingers to open up these small overlaps or flaps to ensure that all that dust like grain is removed. You will find a very fine screwdriver or even a needle to be invaluable in cleaning these petite screens or mesh but I must stress, be very very careful.
It took me about 10 minutes to clean each of these filters thoroughly.
The degree of cleaning needed could not be achieved if the filters are not removed out of there receptacles or enclosures.
One of the filters (the oil inlet) was much more congested than the other.
I then took a very fine grade nail file and tidied up the top of the brass collar of the small mesh filter to ensure any scrapes or abrasions caused by my extraction were filed down smooth in readiness for reinsertion back into the respective orifices in the respective pump body parts.
When the pump body components are all thoroughly thoroughly cleaned ensuring that all the internal channels and journals are cleansed with certainty that the unseen portals or journals or oil-ways are absolutely spotlessly cleansed, then and only then the small filters must be reinserted.
I found it was necessary to press these small filters back into place.
I used vice grips with small pieces of rubber to protect the components from any damage.
This next stage is very very important,
The gear wheels and gear “axle” are a single unit with the gear wheel and the axle being milled as a single piece.
These axles fit into two small hubs that in turn press freely into the pump housing.
Here I made what could be a very significant observation,
There is a very petite cut-away or “Nick” machined out of the bottom edge of one of these hubs.
(This “cutaway or Nick can be seen in some of #indrocruise photographs)
It is vital that these hubs are replaced hub by hub, back into the housing precisely back into the position they came out of.
Thankfully there are only two options or ways to instal these hubs into the housing.
For ease of explaining from here, let’s just say there is the right way and there is the wrong way.
However, installing the right way the fluid can flow unimpeded on its proper pathway,
However installing the wrong way, the pump cannot function as the aforementioned “nick” is in the wrong place thus the fluid cannot flow unimpeded.
(If you were not aware of this observation, you could well complete the entire assembly before realising the pump was not going to work.)
I know I may be wrong here but so far I have never heard anyone mention this small “Nick” and boy is it not a vital part of the pumps mechanism.
I have read and studies hundreds of posts as well as watched many videos but to date I have never heard of or been told to look out for this petite “Nick”.
I suggest this might be the reason why so many people conclude their pump is obsolete after reassemble but in reality it was just that this oil-way was blocked by inserting this hub in the wrong way.
Now as I admitted earlier I didn’t take notes or photograph indeed I took no actual records of the disassemble as I should have done. I was so focused in attention to detail and I will admit one of my bad habits is to rush to reassemble so as to not forget how I disassembled.
Another word for this is “PANICK”
Boy did I have a problem here,
“How do I know which way to re-instal these hubs”
In the end I did a miniature mock up of the assembly and using a fine nozzle and compressed air, I blew the air into the oil inlet hole on the housing, and indeed yes my first attempt was wrong as the air was not getting through. So now I knew to insert the hubs the alternative way.
So by the skin of my teeth I got past this hurdle.
I however could not get out of the next slip up so easily.
I hadn’t marked and recorded exactly where the teeth of the gear wheels met, tooth by tooth.
In this my friends I was defeated.
I had to proceed and hope that the pump would function for me with just a random guess with positioning the two gear wheels.
I wish to share another idea here if I may.
[Public Health Warning]
The following is probably over-kill.
When I was assembling the components of the primary pump assembly I set up a very clean plastic jar in which I filled with New AHC fluid.
Always making sure my gloves were spotless.
I then set the components of the primary assembly into the AHC fluid and I assembled each component under the fluid ensuring each orifice was filled with AHC fluid from the onset of assembly.
This method also meant that all the components of the primary pump were assembled while submerged in the AHC fluid thereby ensuring that all the components were both adequately lubricated as the assembly progressed and it presented the possibility of removing potentially troublesome airlock problems.
Next step is to attach the Main Block of the pump to the primary pump module.
Being conscious of the need to avoid any and all air pockets I unscrewed the AHC Fluid pressure sensor out of the main block, filled the pressure switch orifice with AHC Fluid and then after testing the sensor electrically I reinstated the AHC fluid pressure sensor back into the main block. I then set the “main block” on its side with the large End Cap O Ring looking straight upwards and the electric motor directly beneath sitting on the bench.
There is a second much smaller O Ring sitting inside the large O Ring, on this block face. It is vital this small o ring is kept in its place.
( I promise this all sounds way much more difficult than it really is)
It is crucial to make sure the second small O ring is kept in place. I believe this O Ring seals the faces of the two assemblies at the orifice that allows fluid access to the pressure sensor.
I filled AHC fluid into the upper face of this main block before dropping the primary pump assembly down into the block. Once again attempting to ensure that all orifices were filled with fluid and all joints lubricated.
(This is not a perfect science and it is not possible to do the complete assembly without lifting the components out of the “oil-bath”
There are a two other O RIngs who’s locations are obvious. However these two small O Rings have two small steel backing washers.
It is vital to replace these washers and O Rings precisely in the order they come of.
However thankfully this is also intuitive in nature and can be worked out.
The washer and O Ring sit into a recess, with the steel backing ring going in first. Think of it as a shim that helps the subsequent O ring retain pressure.
So The washer goes into the orifice first, then the O Ring.
One other observation I made was that if you happen to slightly over tighten the primary pump assembly to the “main block” the pump will be too tight and the motor won’t be able to turn the gears in the gear Housing.
(There are proper torque settings for tightening these four studs, but I have not yet found them at this time.)
So I just trusted in my experience and I lightly tightened each stud while at the same time I tested the motor by connecting to a 12volt battery, thereby being able to identify when I was coming closer to the “Sweet Spot”
Once I found the sweet spot I backed all the screws out a half turn, gave the pump a wee tap on the bench, and then brought the tension back up to where each screw should be. (Ie, I don’t trust a bolt being left as finished with a loosening move, it must always be a tightening move)
Now the final “trick” I have to offer is as follows.
The final step of this stage is to attach The End Cap or housing, the black cap with three stud holes in which the primary pump assembly is housed. Or the black cap with the pressed “+” sign and with the temperature sensor attached.
Once again in an effort to ensure all orifices are filled with AHC Fluid, I got a large plastic dish.
The plastic dish was of a size that I could set the the End Cap upside down with the three protruding stud hole tags sitting on the edge of the plastic container.
I then filled the End Cap with AHC fluid.
Next I set the whole pump assembly down onto the end cap submerging the primary pump assembly into the AHC fluid once again in an effort to minimise any and all air pockets as the pump is assembled. The overflow of AHC fluid dropped cleanly into the plastic dish below thus saving it cleanly.
It is very important to make sure this dish is kept very clean so as to be able to reuse the overflowing AHC fluid.
I carefully inserted and tightened the three studs thereby sealing the End Cap onto the whole pump body.
All of the above “exercises” were conducted in an effort to ensure all the internal cavities of the pump were filled with clean AHC fluid and that all moving parts were adequately lubricated throughout the assembly.
Next I built up the entire pump assembly including the oil reservoir. I plugged the oil out port loosely.
I put a litre of oil in the reservoir, connected a 12v supply and observed the pump, pumping oil out the outlet port, pushing out my loose plug at the same time. Then when happy the pump was pumping fluid I plugged the hole loosely again. (Small bit of rag)
And Finally,
I uncoupled the cruisers negative battery earths and didn’t refit for periods 20 minutes.
This was to attempt to rest the AHC ECU.
Ps, When fitting the AHC FLUID reservoir on top of the pump, I filled the reservoir receptor orifice with AHC fluid once again to attempt avoid any air pockets.
I then re installed the reservoir onto the pump.
I put some more oil into the reservoir.
I re-installed the AHC pump assembly back into the cruiser. I re-joined the three plugs, the 12volt motor supply, the temperature sensor and the pressure sensor and the main AHC Fluid “out” line.
I then filled the reservoir to 2/3rds with AHC Fluid.
I bled the outlet pipe again using the 12volt direct method, and then retightened the output pipe.
I then reconnected my battery negative terminals.
I wasn’t sure if I would need to use “The Active Test “ to get the pump going, but I decided to just try.
To my great pleasure I noticed the AHC FLUID exiting the reservoir at quite a speed, and eventually after perhaps 2 or 3 ignition off / on and start engine again cycles.
And magically for the first time in over 3 months the front of the cruised began to rise. I had to keep cycling the ignition from on / off and restart a number of times and was delighted to See the rear of the vehicle rising.
I must admit I was very surprised that the cruiser lifted right up to its maximum height without any further bleeding.
I knew i needed to bleed all the 5 points a few times the next day but
As it was now quite late here I decided to take the cruiser for a drive and I was of to bed.
When bleeding I started with the furthest away bleed point and worked forwards towards the nearest bleed point to the oil reservoir.
Before starting I raised and lowered the system a few times, and then I went from L up to N or neutral before starting bleed process.
I used genuine OEM TOYOTA AHC FLUID ONLY.
IT is crucial to have someone with you when bleeding. For two very important reasons, A, You are lifting and lowering a 3.5t vehicle while lying looking underneath it, real potential to get hurt.
B, You need someone to make sure the oil never depletes out of the AHC oil reservoir as this will introduce air into the system thus defeating the entire bleeding process.
I’ve got this post bookmarked!
