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Thread: e46 Ambient air temperature issue

  1. #1
    Join Date
    Sep 2014
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    2003 BMW 318ci

    Question e46 Ambient air temperature issue

    Ok, I know that this is a common issue for them falling off and needing replacing, this is not the issue, although I thought it was and have a brand new one.

    My dash reads +50c all the time, replaced the temp sensor and still reading the same. I disconnected the white connector at the back of the cluster and it still reads +50 which indicates a closed circuit.

    I hooked a multimeter to pin 1 (ground) and it reads 4.8v.

    I will get -40c if i ground pin 1 wire.

    Where do you think the issue is, and what is the next step to take??

    Thanks in advanced.

  2. #2
    Join Date
    Mar 2018
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    Allen, Tx
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    2006 BMW 325 Convertibe
    Allen 175, I've got VERY similar issues. Did you ever find a solution?

  3. #3
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    EXOTICS

  4. #4
    Join Date
    Mar 2018
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    MIKYZZ4,

    Yeah,Thanks. I've been through all of that and then some. I find myself hoping against hope that there is an answer out there that does not make me replace my cluster. $80.00 on Ebay for a used cluster then another $220 to have the chip moved from original to replacement unit. I could attempt the chip transplant myself but if I screw it up I'm in a world of hurt.

  5. #5
    Join Date
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    '73 E9, '94 E34, '02 E46
    Either do it or put some black tape over it and fugeddaboudit. World of hurt, nothing. There is no try, only do, as Master Yoda says, bless his hairy little head.
    Charlie

    Your mission, should you decide to accept it, is to add value to these threads, either by pictures or by descriptions, so the next person with the same or similar problem stands on your shoulders.

  6. #6
    Join Date
    Jul 2011
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    2018 BMW M240i
    The heat and ac control module (IHKA) uses the ambient air temperature sensor to regulate the ac.

  7. #7
    Join Date
    Oct 2009
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    Torrance, CA
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    1999 323i
    Quote Originally Posted by Arch01 View Post
    I've been through all of that and then some. I find myself hoping against hope that there is an answer out there that does not make me replace my cluster. $80.00 on Ebay for a used cluster then another $220 to have the chip moved from original to replacement unit. I could attempt the chip transplant myself but if I screw it up I'm in a world of hurt.
    It is rare for the cluster to be the problem with the ambient temp circuit, but, it does happen, I think I've repaired a couple. Cluster repair is not that expensive and $220 to move the chip over is crazy. Google "BMW E46 $90 Cluster Repair" and something will come up. Let them know you disconnected the white connector from the back of the cluster and the ambient temp stayed at +122F (+50C). This should not happen! When the white connector is disconnected the ambient temp sensor input of the cluster is open circuit which should read -40 degrees. If it reads anything else then there is a problem in the cluster, period! It can not be a wiring problem or a sensor problem or anything else. It has to be a cluster problem. If the white connector is disconnected and the temp reads +122F (+50F) don't both testing the wiring, measuring the sensor resistance because the problem is not out that end, it's in the cluster.
    Last edited by scottjoh; 03-28-2018 at 07:21 PM.

  8. #8
    Join Date
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    To add to what scottjon has written, if the sensor is fine if check the wiring from the sensor to the harness. You can pull the gauge cluster and perform a resistance check of the sensor and the wiring. The sensor itself is a negative temperature coefficient thermistor. That is, it’s resistance decreases as its temperature increases.

  9. #9
    Join Date
    Feb 2012
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    Tbilisi/Georgia
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    2002 E46 M3
    hello people,

    anything new about unmentioned issue ? i got same problem with my car (02 E46 M3). it reads +50C all the time (no matter how many sensors i'v tried), then i swapped the cluster (non M///) and surprisingly it worked just fine (showed correct Temp). so now i'm in trouble with cluster and since it is an M/// version its not a cheap replacement you know ))

    please give any ideas / solutions

    Regards

  10. #10
    Join Date
    Feb 2012
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    Tbilisi/Georgia
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    2
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    2002 E46 M3
    anyone ?

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