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Discussion Starter · #1 ·
It appears an alternate pressure sensor is badly needed. Monkeywrenchracing has been selling “used” sensors, but they’re out. New sensors are not even listed in Toyota parts breakdowns. And forget about LUK offering ANY support for their products - many have pleaded and begged. None have succeeded.

I invested $22 and ordered this one from Amazon. The pin pattern and connector is (almost) identical. I shaved off one rib from my HPU connector and it slides right on. The threaded barrel needs a solution. Possible alternate sensor has an M12x1.0 thread. SMT sensor needs M10x1.0. Also the body is too big and it will crash with a solenoid, so it needs a spacer/adapter to reduce the tread size and space the sensor about 3/8 inch further away. With that solved I can hook it up to a functioning system and see if it works. WHO HAS A LATHE?
I do see different resistances on the three pins when comparing the two sensors. Unfortunately the BGB doesn’t show me correct resistances.

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I believe only SMT Spyders were sold in Australia.
Have you tried to find parts from Australian sources?
 

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Discussion Starter · #3 ·
I haven't worked very hard to find used sensors. I actually don't need any. This is an exercise to help the community find a better source of sensors than MonkeyWrench, who is currently scarfing up all the used GSA and HPU, and selling parts for hefty prices. Like $145 for one used pressure sensor.

I had some limited success today. Installed one BMW pressure sensor on my HPU and it worked perfectly. However - it threw P0942 code "accumulator pressure error", and the run time for pump recharging was much too long.
 

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Discussion Starter · #5 · (Edited)
More details on my tests yesterday: Max pressure reading with the BMW sensor installed was 33.5 bar (should have been about 60 bar). Some helpful guys on facebook group reasoned that the low reading (which was likely inaccurate) caused the TCU to run the pump for the very long charge-time, trying to reach it's preferred min pressure of 42 bar. Regardless, the car shifted and ran perfectly - but threw the P0942 code.

Other peculiar behavior - with ignition on, the bleed down and recharge cycle was much too fast. About 15 seconds bleed down time, then 5 seconds recharge. (Normal cycle with the correct sensor installed is about 1 minute bleed down, and 10 seconds recharge)

I'm slowly finding other sensors for various applications, mostly anti-skid systems. It would be nice to find a part number de-coder to aid in selecting the closest sensor. However price seems to vary widely. The BMW sensor I tested costs $22 on Amazon. Joe Premecz found a sensor for "Ford Transit Durashift ASM" that has a part marking that is only a few digits off - however it costs about $90 plus shipping. The finally solution may be to select a cheap sensor and modify the output voltage.

I did some googling and found that these sensors are likely "Ceramic Capacitive Pressure Transducers". I also found a similar part number decoder, but nothing that decodes our exact sensor. I wonder if the numbering system is an industry standard, or specific to the manufacturer? (This is far out of my area of expertise!)

I will post screen grabs.

Any help deciphering this puzzle would be appreciated!

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My advice is to find a local instrument calibration company that can hook the stock sensor up to a hydraulic pressure calibrator and give you the characteristic voltage or resistance vs pressure curve for the sensor. Then find a sensor that matches that and ideally the port size. Forget the electrical connector matching just splice a new one on to match the replacement sensor. Digikey has lots of fluid pressure sensor options.
 

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Discussion Starter · #7 ·
My advice is to find a local instrument calibration company that can hook the stock sensor up to a hydraulic pressure calibrator and give you the characteristic voltage or resistance vs pressure curve for the sensor. Then find a sensor that matches that and ideally the port size. Forget the electrical connector matching just splice a new one on to match the replacement sensor. Digikey has lots of fluid pressure sensor options.
Good idea. I can buy a pressure gauge at harbor freight for $8. I have a GSA bench tester that will show voltage so I can create my own curve.
 

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Yeah you will need a hydraulic pump and good pressure sensor plus the fittings to build some kind of manifold. Most of those sensors are a straight line 0.5 to 4.5V over their sensing pressure range.
 

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Yes very expensive because of safety regulations surrounding high pressure hydraulics. Search 'high pressure fluid injection injury'. Or maybe don't.
 

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BTW, the minimum system pressure should be 38 bar when the pump recharges to a maximum of 55 bar. My thinking is we need a sensor with a max value of 55 bar (around 800 psi) because the output voltage will be linear and proportional to pressure. I think it’s important to be fairly accurate at the 38 bar mark for recharging. I like that you’re using the “run times” for comparison, and it’ll be interesting to see how that matches with the pressures you find when testing.
My guess is if a sensor is found, or one is custom made, the price will be in the $150-200 range for a quality one.
 

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The sensor may have a much higher sensing range than the max pump pressure the only way to find out is to test the stock one if a data sheet is not available. $150 to $200 could be about right plus the cost of the wiring connector and any mechanical adaptation for the threaded end (hopefully avoidable by finding a sensor with matching threads).
 

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I wonder if Kavlico can determine what’s needed and customize one by sending them a good working OEM sensor. The reason I never pursued it was because I assumed it would be cost prohibitive. IIRC, I had to enter a company name just to get the information that I posted earlier. If we ever do run out of theses sensors, we’re dead in the water.
 

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Would be expensive. I used to work for a pressure sensor manufacturer - there aren't a lot of different pressure ranges for the sensors so it should be pretty easy to determine the range of the stock sensor and find one with the same range that is all metal inside or seals compatible with the SMT fluid. Matching the threaded connection is also a bonus. I would say trying to match the wiring is a stretch goal.
 

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I haven't worked very hard to find used sensors. I actually don't need any. This is an exercise to help the community find a better source of sensors than MonkeyWrench, who is currently scarfing up all the used GSA and HPU, and selling parts for hefty prices. Like $145 for one used pressure sensor.

I had some limited success today. Installed one BMW pressure sensor on my HPU and it worked perfectly. However - it threw P0942 code "accumulator pressure error", and the run time for pump recharging was much too long.
Hello cyclehead you might want to check with Robert at MLREng i got one for my 2002 looks exactly same except different metal color good for up to 100 bars works good so far they are a pump company so they should have other parts also
 

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Hello cyclehead you might want to check with Robert at MLREng i got one for my 2002 looks exactly same except different metal color good for up to 100 bars works good so far they are a pump company so they should have other parts also
Also there sensors are 95.00
 

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Excellent contact! They appear to repair similar systems for BMW, Maserati etc. They should speak our language.
Excellent contact! They appear to repair similar systems for BMW, Maserati etc. They should speak our language.
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Excellent contact! They appear to repair similar systems for BMW, Maserati etc. They should speak our language.
Also Berkhart Engineering has what looks exactly like the factory sensor.
 

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EE here with a background in pressure transducers in a previous life.

I have an alternative for you. Buy an affordable sensor that fits and has a higher pressure scale than the OEM sensor. Use a cheap $7 microcontroller to remap the new pressure curve to the OEM curve. Everything you need is already there. 5V source, 0-5V signal line and a ground. It would take me an hour or two to write a controller program if I had both curves.
 
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