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Temp sensor testing?

Discussion in '1st Gen Tundras (2000-2006)' started by wiggilez, Apr 9, 2021.

  1. Apr 9, 2021 at 4:46 PM
    #1
    wiggilez

    wiggilez [OP] New Member

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    Is there way to test the temp sensor? the needle in the cab is always in the middle from start up till I shut it off.
     
  2. Apr 9, 2021 at 4:58 PM
    #2
    Jack McCarthy

    Jack McCarthy Truck repair enthusiast; Rust Aficionado

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    Does it go right to the middle as soon as you turn the truck on when it’s cold? I usually have to drive for 5 miles before it comes up to temp (in the middle) like yourself.
     
  3. Apr 9, 2021 at 5:46 PM
    #3
    wiggilez

    wiggilez [OP] New Member

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    pretty much as soon as its running the gauge goes straight to the center point.

    edit: it does it even in the winter when it's -15c out.
     
  4. Apr 10, 2021 at 9:15 AM
    #4
    BubbaW

    BubbaW Been Real

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    I would not discount the temp gauge sensor which supplies temp gauge reading on cluster. If AC and DC are same, my DC has the temp gauge sensor at same location as temp sensor. It will have one lead to it sending back to gauge. Mine is located on the passenger side front of engine next to temp sensor somewhat under the black cover that says V8 4.7. I would suggest troubleshooting that item also.
    1A9B8D1E-1918-4630-AC28-CAA029B04A89.jpg
     
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  5. Apr 10, 2021 at 6:38 PM
    #5
    wiggilez

    wiggilez [OP] New Member

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    I'm kinda hoping that its the temp sensor, but I'm trying to figure out if there is a way to test if the sensor to see if that is my issue or if its something more involved.
     
  6. Apr 10, 2021 at 7:41 PM
    #6
    Jack McCarthy

    Jack McCarthy Truck repair enthusiast; Rust Aficionado

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    If it’s anything like most temp sensors I’m familiar with then it’s just a variable resistance under temperature. It should be specified in the repair manual. If that’s the case, you could probably test that it reacts to temp with a simple heat gun or hair dryer and use a multimeter to measure the resistance.
     
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  7. Apr 10, 2021 at 10:17 PM
    #7
    wiggilez

    wiggilez [OP] New Member

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    good enough, guess I'll spend a few hours playing with it tormmorw :)
     
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  8. Apr 11, 2021 at 4:41 AM
    #8
    BubbaW

    BubbaW Been Real

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    Understand fully but the reason I personally would be looking at the temp gauge circuitry(temp gauge, wire to cluster gauge and Instrument cluster itself) is because that's how we see our idiot reading. In your case the temp gauge reading is abnormal.

    The coolant temp sensor talks to the ECU.

    Question just in case we are clear. The moment you start vehicle, the gauge shows 1/2 way ?
    If you turn key to IGN ON only, does the cluster gauge show a 1/2 way reading ?
    If you unplug the temp gauge sensor and put a gnd to that conductor, does your needle go full scale ?
     

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  9. Apr 11, 2021 at 10:56 AM
    #9
    wiggilez

    wiggilez [OP] New Member

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    That I have not tried yet. and yes. after i start the truck a couple seconds later it rises to the center then never moves even on hot days pulling a trailer.
     
  10. Apr 11, 2021 at 12:11 PM
    #10
    peanut

    peanut making uneconomical choices about my truck

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    Check the ECTS fuse in the fuse box under the hood.
     
  11. Apr 13, 2021 at 7:23 AM
    #11
    jggeere

    jggeere New Member

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    I have the same issue. I start the truck when it’s cold and it immediately goes to the middle. Replaced the engine coolant temp sensor but that didn’t work. Did you resolve the issue?
     
  12. Apr 13, 2021 at 7:28 AM
    #12
    BubbaW

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    You sure about that acronym ?

    “electronic control throttle system”....curious your thinking behind that suggestion ?
     
  13. Apr 13, 2021 at 7:40 AM
    #13
    peanut

    peanut making uneconomical choices about my truck

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    Oh hahaha my dumb ass thought it was "engine coolant temperature sensor" :playball:
     
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  14. Apr 13, 2021 at 7:44 AM
    #14
    BubbaW

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    U may not be a dumdass after all....some do refer to it as that....just curious !
     
  15. Apr 13, 2021 at 2:56 PM
    #15
    wiggilez

    wiggilez [OP] New Member

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    I haven't had time to poke around yet. I'm hoping things while quiet down in a week or 3.
     
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  16. Feb 7, 2022 at 5:37 AM
    #16
    Celifis72

    Celifis72 New Member

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    Any results on this? I just bought a 02 tundra and as soon as I start it, temp jumps to center. Very odd!!
     
  17. Feb 7, 2022 at 10:00 AM
    #17
    shifty`

    shifty` Is the Gila Copter a love machine?

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    Sounds like your sensor is shorted. Temp sensors are often just a simple device that increases output signal based on a stimulus, output is often resistance. If it shorts out, it's not uncommon across any make/model to output a constant, whether that's constant zero, constant off-the-charts, or constant middle. Sometimes where it shorts can depend on the type of sensor it is. OEM replacement sensor is cheap enough, and not too touch to replace.
     
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  18. Feb 7, 2022 at 8:16 PM
    #18
    NickB_01TRD

    NickB_01TRD You don't need less cars, just more driveway.

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    Just make sure you are messing with the proper 1 wire sensor. Two sensors on these trucks (and most toyotas from this era) one for ECU and one for gauge. Don't cheap out on this sensor. Get a good brand or even better OEM. I put a cheap one in my 96 Camry (same sensor) years ago and the temp gauge will pretty much be at H even when it's at a normal temp.
     
  19. Feb 8, 2022 at 4:42 AM
    #19
    bmf4069

    bmf4069 Yup, that's car parts in a dishwasher

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    images (5).jpg
     
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