Coolant sensor replacement?

Discussion in 'Electrical & Stereo' started by MrPool, Jul 20, 2016.

  1. MrPool

    MrPool New Member

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    Hey guys,

    So, I recently bought my '97 GT and I need to get it smogged. Everything should be in order except for one issue: There's an MIL code throwing a check engine light that pertains to my coolant temperature sensor.

    The thing is...which one do I replace? I know there are two sensors on a 4.6 V8 (One for the instrument cluster, and the other for the ECM), but I'm not sure which sensor is faulty and could be throwing the code. I've already tried replacing the one next to the intake a couple of times, and that doesn't seem to have fixed anything so far. The wires don't appear to be damaged either.

    Any ideas which sensor I should be looking at replacing? The left side, next to the alternator? Or the right side, in front of the intake hose?

    Thanks guys.
     
  2. ttocs

    ttocs Legend

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    try disconnecting the one you have not done and see if any more codes are thrown
     
  3. 07GtS197

    07GtS197 Well-Known Member

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    You could measure the resistance of both hot and cold to look for discrepancies.
     
  4. ttocs

    ttocs Legend

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    now that I think about it though I had mine disconnected for a long time and all it did was kill the dash gauge, never had a light. I don't think it reads to the computer at all so I would guess its the one not going to the dash.
     
  5. AzzLyp

    AzzLyp Member

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  6. MrPool

    MrPool New Member

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    Yeah, I used that troubleshooting thread before to try to figure it out...As long as both sensors are in the same place on the engine it shouldn't make a difference.
    I'm starting to think that from the "wiggle" test it's probably the wiring harness, so I'm likely to go from there...I'm not 100% sure yet though.
     
  7. MrPool

    MrPool New Member

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    So, having officially attempted to place the new sensor in BOTH of the ports (just to figure out which is which), my only logical conclusion is that it is in fact one of the wiring harnesses. I did a voltage test of one of the sensor wires recently as well and it seemed to be producing lower than normal voltage, so that's likely my problem...

    The only other thing I found curious was that the new sensor had a bit of trouble going into the thread in both ports, despite being the correct verified part number. I have the aluminum crossover on my intake header so maybe that might have something to do with it? Anyone know anything about this?