tn7con

I got the Mini VCI cable & sw from ebay, search for "Mini VCI Toyota J2534" and you should get lots of choice.
I bought it from here: http://www.ebay.com/itm/182462130797 (TechStream version 10.30.039). TechStream sw is only compatible with 32-bit OS version of WinXP/Win7 and should install just fine without any additional steps. To install in Win7/Win8/Win10 64-bit OSes, you will need to extract the included driver from the MVCI driver for TOYOTA.msi file then install the mini-VCI cable drivers manually and then apply some additional hacked entries into the OS registries. Check out this link for install help: http://www.ft86club.com/forums/showthread.php?t=73034

After installing the TechStream sw & mini VCI cable driver on your laptop, take the laptop to your RX, with engine still OFF, connect the mini VCI cable to the OBD2 port (located driver side/below the dash/above the brake pedal area). Start the engine (parked/idle), start TechStream sw on laptop and select "Connect to vehicle". Search youtube for many TechStream "How-to's" videos.

To answer your other questions, pics 1-4 are screenshots from TechStream sw running BEFORE booster circuit was installed. After you confirm that your issue is B1479 and the low flow sensor voltage (below 3.8v when AC is OFF, i.e. pics1-2) you can then select "Active Test" (yellow highlighted button in pic 3) then select Climate Control (or Air Conditioner) subsystem then choose "Magnetic Clutch Relay" test, and then select ON to manually engage the clutch to see if your AC compressor is running and producing cold air (pic 3). Then observe the temperatures & flow sensor value (should be dropping) in pic 4. If everything looks good then you are sure that a booster circuit would likely fix your B1479 issue. Then select OFF to turn off the Magnetic Clutch Relay before exiting the TechStream sw. Depending on how low your Flow Sensor value (when AC is OFF) you should use a different R2 value to boost your Flow Sensor value to around 4v (good valid range is 3.8v - 4.2v).

To build a booster, see diagram for connection reference, depending which op amp you will use, the op amp pin numbers may be different but connection is the same You will need a cable with 4 wires. I used a short CAT5/6 cable (4 pairs, each pair is joint as a singe connection for additional strength & better current flow). However, the OEM wires from the [F50 connector] pins 7/13/30 are thin (probably 24 gauge wires) so you could use only 4 single wires of the CAT 5/6 cable, these are also 24 gauge wires.

Does it help?

tn7con

>> Any recommendations on the techstream cable/sw brand or model, where do i hook up the techstream ?

Search "mini VCI techstream" on ebay or Amazon ...

>> So the make the booster , need an 8 wire cable.

No, you'd need only 4 wires, I happened to use the CAT5/6 cable with 4 pairs inside, I soldered each pair together as one thicker wire. IMO, 4 wires inside CAT5/6 cable are fine...

>> pictures 1,2, are reading or data prior to connecting booster fixture.and engine on?
>> pic 3, data during test, booster installed,engine on, ac on
>> pic 4, data after 3 minutes of test, booster installed engine on, ac on

Pics 1-4 show test BEFORE booster installed just to confirm B1479 code was there and when manually engaging AC magnetic relay, the system would cool ok ...
The rest of your captions are correct ...

tn7con

>>>Any recommendations on the techstream cable/sw brand or model, where do i hook up the techstream ?

Search youtube on how to use TechStream ...

>>>So the make the booster , need an 8 wire cable.

No, you'll need only 4 wires. I used 4 pairs of wires (from CAT/6 cable) soldered each pair as one thicker wire, 4 single wires should do fine ...

>>> pictures 1,2, are reading or data prior to connecting booster fixture.and engine on?
>>> pic 3, data during test, booster installed,engine on, ac on
>>> pic 4, data after 3 minutes of test, booster installed engine on, ac on

No, pics 1-4 are screenshots before any booster circuit is installed.

mitserolf

Thanks again for some clarifications. Today i brought my car to a friend mechanic, i asked to scan my car,, but when he scanned there were no codes showing ,,i was hoping to see error code B1479 as mentioned by car dealership service guy. Still i dont have air con,, no code B1479. Is there any explanation to that. im not sure if Lexus cleared the error through his shop scanner machine.

Is it possible that when i brought the car first time to Lexus ,, the mechanic might have siwthed off my ac through his scanner. He replaced serpentine belt, idler pulley, replaced transmission oil(saw him using computer during transmission oil change.

I watched some You tube Techstream videos. I saw a video showing in techstream a lot of a/c related menus, some ac related you can switch on/off some ac related task. Im wondering if my problem isnt related to ac compressor, but simply programming screw up. because it was perfect working ac , before i brought it there.

I just want to make sure,, before i play i make and apply this booster tyou created.

Any further advise. what happened to code B1479. My car was scanned today,, no errors.

Thanks again.

tn7con

What year is your RX350? If your friend mechanic is using a standard handheld OBD2 scanner, it's not going to find any Toyota/Lexus internal code. Most handheld OBD2 scanners only scan/report Generic Pxxxx code, not Toyota/Lexus specific code Bxxxx. You will need Techstream to read internal Toyota/Lexus code ....

Also check the service bulletin from the link at the beginning of this thread to see if your VIN is smaller than the VINs shown there. If it is then the B1479 service bulletin applies to your vehicle...

mitserolf

my rx350 is 2010, he doesnt use techstrem,, itss traight up scanner, not connetected to lap top. he said.if theres no "check engine light" his scanner will not see any anything. so could be the reason why. but back to my other q ,, is it possible to switch off compressor through techstream?

thanks.

mitserolf

yes my VIN is smaller than the VINs shown there. If it is then the B1479 service bulletin applies to your . so its abulletin .not a recall?
thanks again...You started this thread a year ago now,, i suppose your rx ac is well functioning till now. Some of my tech friends are hesitant to apply this to my car,, they said if they do,, they dont want to be blamed if they mess up something else.
So i cant find anyone here to work on my problem and create the booster.
Onesaid he can apply additional voltge to that wire to compressor,, just to see if it would run the ac,, but he went on vacation the next day. ill wit then when he come back.


Ill keep asking. Thanks.

tn7con

I don't think the Lexus tech did anything to your car to make the AC stop working ... B1479 seems to be an issue with the defective flow sensor built into many AC compressors from VW/Audi, Toyota/Lexus...
I didn't start this thread ...btw ... but using the booster circuit, my AC compressor works fine again ... mine is also 2010 RX350 model ...
Lexus will repair/replace the AC compressor if your car is still under warranty ... your best bet would be to find out for sure if your car has DTC code B1479 using Techstream, check/confirm the flow sensor voltage is below 3.8v when AC is off. If so you can use the Utility function in Techstream to manually turn on the Magnetic Clutch to see if your AC compressor is running and your vent has cold air again ... then build the booster circuit, it works for me and could work for you as well ...
Your next cheapest method is to buy a new flow sensor (on ebay about $50-60) and replace it in the compressor, then recharge the system ... this would cost a few hundred bucks but much less than replacing the whole AC compressor ...

tn7con

Another thing your mechanic friend could check is to make sure all wiring/connectors on the AC compressor have tight connection. It's possible that whoever worked on your car might have disconnected some cables from the AC compressor and/or some connectors didn't snap back tightly thus the AC compressor stops working ... never hurt to check ...

mitserolf

Hi , thanks for the additional check,,just reading your last advise,, I might ask someone to check that,, however I was told to get to the compressor how many harnesses or connectors go to ac compressor? How complicated is it to access the compressor? That's what I suspect initially, but I have gone back to lexus and they said they checked all , connections, fuses and scanned ac thus getting B1479.. If there is a connection problem will I stll get the error code B1479? or something else error which code is different? I don't have any 'check engine , or any other warning light onmy dash". Thanks again. I tried the last 4 days,, switching on and off this ac,, auto, dual switches,, but no luck. I was hoping it can kick start the ac in case it became intermittent as well. but no luck.

tn7con

Based on internet pictures of the AC compressor TSB19C, I believe there are 3 external connectors on the AC compressor. I can relate to what you are going through right now, I was in the same boat But after trying all what you tried, I realized the only way I could know for sure is to get the mini VCI cable and TechStream sw as suggested at the beginning of this thread to see if the code B1479 is set and the actual low voltage of the flow sensor. Then to build a booster circuit as recommended above. Either that or pay someone else big bucks to replace the AC compressor ...

tn7con

Here's the picture showing 3 connectors on the AC compressor, hope it helps someone ...

mitserolf

Hi TN7CON,
Thanks so much again for the picture. SO its possible that mechanic might have unknowingly touched any of those cable plug connects. If the D10 connector was slightly touched,, will there be no power to the AC sensor or clutch?. Yes youre 100% correct regarding the headache im going through, after spending 1600 on Serpentine belt, idler pulley, transmision oil, engine oil , changes, i came out with unexpected AC problem. Its hard to believe my AC was 100% working before all those jobs by lexus. Now they have quoted me with 2300$ job, replace compressor and AC clutch. I asked around even for used or jobber parts,, from 300 to 700 , plus labor. Im not even sure if i ask a non Lexus garage if mechanic even know how to get to the compressor because of tight squeeze. Ive read , mechanic migh need to remove bumper, condenser, alternator,, Tech as . Im even now tempted to forget about AC. But im still goint to get techstream, to confirm B1479,and it could be useful for other future tests on this car, but my problem is i cant find anyone here to make me the booster. unfortunately im not as Handy techy as you are. I appreciate all the help youve been sharing. Thanks .

mitserolf

Hi TN7CON, attached pics for your info. Mine and your pic, seems exactly same wire color coding and pin location on F50.
thanks.

tn7con

This is good ... the biggest (middle) connector is the F50 connector, press the locking tab on the right to release it and pull the connector out ....