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2012 Tacoma V6 climate control wiring mods?

Discussion in 'Technical Chat' started by kx250rider, Jul 29, 2012.

  1. kx250rider

    kx250rider [OP] Member

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    Charles
    Ventura County, CA
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    '96 4x4 Hilux 2.8 Diesel, '12 Prerunner V6
    Converted legally in CA to a Toyota "3L" 2.8 Diesel from Germany
    I just got a new '12 Prerunner TRD Sport V6 auto, to replace my '05, which was getting way up in miles. I love the new truck, but yesterday I drove it up to the desert, and discovered a serious annoyance with the heater-A/C controls. In the '05, the hot/cold control, the compressor, and the recirculated air were all driver-controlled. With the '12, the controls look the same, but the compressor and recirc are locked "on" when you dial the temp knob to coldest (or asking for no hot water circulation). I'm a little OCD, and I have this mental picture of a little bit of hot water seeping through the heater coils when all I want is unheated/uncooled vent air from outside.

    MY QUESTION: Has anyone else disliked this feature, and/or have you done any mods to change it back to how the earlier gen II had it?

    I will repost here with what I do about it. I'm an electronics tech and electrician, so I'll most likely be able to figure out a mod for it without disturbing the factory harness or affecting the warranty. But if someone else has, and I missed it in the search, thank you in advance :)

    Charles
     
  2. whippersnapper02

    whippersnapper02 Well-Known Member

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    Yes someone bitched about this before. No mod was done and he eventually lived with it.
     
  3. kx250rider

    kx250rider [OP] Member

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    Converted legally in CA to a Toyota "3L" 2.8 Diesel from Germany
    Glad I'm not the only one (I usually am, LOL)... I'll get on it today.

    Thanks, Charles
     
  4. whippersnapper02

    whippersnapper02 Well-Known Member

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    I just don't see why you can't leave the dial one turn above the labeled "MAX AC." I bet if you pull the compressor wiring and measure temps between MAX and the notch above it, there would be no temp change.
     
  5. DEEVON911

    DEEVON911 Semi-pro

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    Bethel Park, PA. Burb of the Burgh.
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    TRD Cat-back Exhaust. Semi-Debadged. Shorty 8 in. Antenna. Weathertech vent visors. TRD FJ Cruiser Center Cap Wheel Mod. Nitto Terra Grapplers. Inverter tapped into for outlet in cab. Tacomaworld sticker which adds 5 hp.
    I think I understad what your saying. My 2010 does the same thing. I actually like it, mine says Max A/C at the all the way cold point, so when you put it there it recycles the air automaticaly, then when you just back it off alittle, it turns off the recycle and lets in the fresh air. On mine, I can feel like a little "stop" and then I hit the Max A/C where it does what you say.
     
  6. kx250rider

    kx250rider [OP] Member

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    Converted legally in CA to a Toyota "3L" 2.8 Diesel from Germany
    I decided to mess around with it, and I discovered that the "max A/C" command is generated within the A/C computer; not in the control panel as I had hoped. What I had hoped was, that there was an extra contact on the temp dial, which would close and send a turn-on signal to the compressor clutch and air mix damper servo. This is not the case, or I would have been able to simply cut the trace on the board for that position. I disassembled and reverse-engineered the control head and board, and although I could have missed something, it looks like I'll have to live with it, or put bypass/interrupt switches in the power feeds to the air mix and vent damper servo motors, if I absolutely can't overcome the OCD issue.... Before anyone blasts me for fooling around and ripping stuff apart on a truck with under 200 miles on it, rest assured as I'm a former microelectronics technician, and have plenty of experience working on camcorders, digital camera, etc. In other words, yes it's back together, and there weren't any parts left over ;-).

    On a practical level, I agree... But it's a pet peeve for me, when a computer or device, takes control of something away from me. My wife couldn't agree with you more regarding the A/C & heat controls, and can't believe I'd even notice it, let alone want to alter it. It's kind of like spell-check and auto-fill in phones and on computers. I turn all that stuff off too, and I have disabled the lid lock on our washing machine.

    Charles (stubborn Irishman) ![​IMG][​IMG]
     
  7. DEEVON911

    DEEVON911 Semi-pro

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    :confused: Just don't turn it all the way to Max A/C. You are still in control. It doesn't care how cool you are. Or does it? :eek:
     
  8. tubesock

    tubesock Well-Known Member

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    Don't think of it as handholding, consider it a shortcut key right on the dial. If I want maximum coldness I can just hamfistedly slam my dial to the bottom and it turns on the compressor and closes the vent. Instead of having to turn the dial and press 2 buttons which are not close enough to hit them both at once. And if i don't want recirculated air, then I don't slam it to the bottom. Like someone mentioned, you can feel tactile resistance when you make that last jump.
     
  9. kx250rider

    kx250rider [OP] Member

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    True and reasonable... But it still bugs me :annoyed: .

    I have a habit of always reaching for the air temp knob, and being sure it's all the way down; the same as putting the key in the ignition. Now I have to remember not to do that, if I don't modify it. I can't find a factory '12 body wiring diagram online, so I'll try to stop by the dealer and get a printout asap. It's not only to fix an annoyance; it's one of those things that will bug me if I don't at least find out what the engineers did....

    Charles
     
  10. 03is300ztk

    03is300ztk Well-Known Member

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    Well all the MAX AC setting is for, is the recir option, doesnt change the ac temp, it should feel cooler because its no longer drawing the fresh ambient air in, its recirculating the already cool air thats in the vehicle.
     
  11. dibble9012

    dibble9012 Well-Known Member

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    Accord to the PDF below, if you can find or make (using resistors and a diode) a .5V to .7V source, and attach it to pin 2 of connector A33, it would prevent the max AC setting from coming on. If installed correctly on pin 2 of connector A33 (or internal of the climate control panel on that pin) it would ensure there is always at least .5V on that line. The max AC setting would never come on since the climate control ECU is looking for 0V to .4V on that line.

    2012 Climate Control Pinout
     
  12. kx250rider

    kx250rider [OP] Member

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    '96 4x4 Hilux 2.8 Diesel, '12 Prerunner V6
    Converted legally in CA to a Toyota "3L" 2.8 Diesel from Germany
    Yes & no... My issue with the A/C control, is that it has taken control of the various parts of the system out of my own control. The fly by wire still lets me decide how much gas to give. I don't like antilock brakes, but I can tolerate them. There are rare occasions when locking up the brakes could be necessary to induce a skid, as in if I'm going to hit something, I might rather spin the rear around to hit with, which I'm not saying I'm good enough to guarantee, but at least I'd rather have the chance to try. In a sure-head-on crash, if you don't have time to steer, you may still have time to spin left, and cause the oncoming car to hit in the passenger side (hopefully to the rear or the front of center), and avoid a dead blow hit, and disburse some of the impact into spinning both vehicles. In fact, my ABS brakes in my '05 Tacoma nearly CAUSED me to crash into the back of a car that stopped for no reason at the bottom of a hill on a badly washboarded road. The ABS kept releasing the brakes, "thinking" that the washboarding bounce was a lockup. Luckily I was driving at a safe speed, and had time to brake several times.

    Thank you for that page! I had not yet been able to get hold of any '12 wiring diagram, and therefore had put the issue aside for awhile. I'll get back on it, and will post up results.

    The other thing I think I noticed, is that there's no hot water cutoff valve. That will be corrected!!! I'll put an electric one that cuts the hot water with a switch I'll add.

    Thanks again!!!

    Charles
     
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