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04 Taco - Engine Coolant Temp. Sensor?

Discussion in '1st Gen. Tacomas' started by gunn, Apr 27, 2009.

  1. gunn

    gunn [OP] Member

    Joined:
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    Durango, CO
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    04 xcab SR5 4x4 5spd
    Hey guys,

    New to the forums :wave: and looking for some advice on this issue.

    I just bought a used 2004 Tacoma with 55k miles. It's the V6 4x4 extended cab. Loving it! Although I already cracked my windshield :(

    I didn't get the extended warranty (hmm, wondering now) from the dealer so it's out of warranty. One thing I didn't notice while looking and driving it at the dealer was that the engine temperature gauge doesn't work. Here's what I've found:

    -When I start the car up in the mornings (it's still in the 20s here in Durango at night) the gauge automatically jumps up to the midpoint. It spends no time at all on cold.
    -While driving the car the gauge never moves from this midpoint position.
    -The heater works fine as it should. The truck idles fine and nothing else indicates that there is an issue. The check engine light has not come on.

    So, my original thought was that the ECT sensor is faulty but I would expect the check engine light to come on if this was the case. Is there a fuse somewhere that sits between the sensor and the gauge?

    Has anyone seen this happen to your Tacoma? What do you think is going on? I'd like to fix this one myself and avoid the shop.

    Thanks!
     
  2. bobwilson1977

    bobwilson1977 Well-Known Member

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    none except for crappy hub caps and floor mats.
    That is definitely weird. When you say it jumps to the mid range, do you mean it does it as soon as you turn the truck on, or after its been running a little bit? When the truck has warmed up, is the radiator hot to the touch? That would be my first order of business because one other reason the temp gauge could jump up is if there's some sort of blockage.

    But I'd at least put the truck on a scanner and see what comes up. Its possible that whoever sold it to you reset the computer and erased the codes.
     
  3. gunn

    gunn [OP] Member

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    04 xcab SR5 4x4 5spd
    As soon as I turn the truck on/crank it over it goes to the middle (actually just above the midline). This is after sitting in the cold all night.

    I'll check it with a scanner and see what it pulls up and let you know. Thx!
     
  4. bobwilson1977

    bobwilson1977 Well-Known Member

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    none except for crappy hub caps and floor mats.
    I think you might be right then. It sounds more electrical than mechanical.
     
  5. gunn

    gunn [OP] Member

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    OK, pulled the codes at Autozone--"No codes found". I'm thinking it might be the sending unit but I'm not sure.
     
  6. EnolaGaia

    EnolaGaia Well-Known Member

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    01 SR: Double Cab conversion, S/C, lowered.
    No, there's no fuse between the temperature sender and the gauge in the cluster.

    Failure in the coolant temperature gauge or circuit would not / does not trip a CEL of any kind.

    Either the sender or the cluster temp gauge is messed up. There's an outside chance it could be a wiring fault (e.g., bad ground).
     
  7. gunn

    gunn [OP] Member

    Joined:
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    Durango, CO
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    Well, finally taking a look at this again and I've decided to replace the sending unit ($15) and see if it improves. It's a royal pain in the ass to get to but so far I have:
    1) Removed timing belt cover bolts
    2) Instead of draining the coolant I have slid the upper radiator hose clamp down the hose (zip tied it to keep pressure off the hose) and slid the timing belt cover down. Hopefully I won't lose too much coolant when I remove the sending unit.
    3) Loosened one bolt on the fuel pipe and it was getting dark so I came inside after trying to get the second bolt loose. I think this second bolt is going to be a pain to get off.

    See: http://ncttora.com/fsm/2003/Repair_Manual/03tacoma/sf5vzfe/ects/insp.pdf

    Anyway, nothing simple in the world of vehicle wrenching! :) For now, it's better than paying for such a simple problem...I'll let you all know tomorrow if replacing the sender fixes the problem.

    Oh, the service manual says that the gaskets on the fuel pipe should be replaced. Isn't that kind of overkill?
     
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