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temp gauge goes to half as soon as I turn key

Old 03-31-2014, 09:43 AM
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temp gauge goes to half as soon as I turn key

I replaced both coolant temp sensors. The one for the computer and the temp sensor for the gauge in the dash. Any idea why the temp gauge goes right to the half way mark as soon as I start the car? The motor is cold so I have no idea why it would read incorrectly.
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Old 04-01-2014, 02:49 AM
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You posted a low-info Q. They usually get low-quality responses. Here's mine.

Just guessing: Did the weird one work right before you replaced it? If so, why did you replace it? What was the problem you were trying to fix?

If the weird one worked right before you replaced it, your hook ups are wrong - or dirty - or broken. Or the new sensor is bad. Is every part OEM at this point?

I guess I would put the old ones back in and see if they perform as they did before I removed them. At least I would start there. Does your FSM have any advice? Sorry I can't be more helpful.

Last edited by zxguy1986; 04-01-2014 at 04:51 AM.
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Old 04-01-2014, 05:42 AM
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It did not work before I replaced it. Hook ups are clean and no broken wires. I assume it is a problem between the sensor and the gauge.
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Old 04-01-2014, 12:50 PM
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My second guess would be a wrong part for the car. Sensor or gauge. Sounds like sensor sending wrong signal to gauge - or gauge misreading signal. Let us know what you find out.
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Old 04-01-2014, 05:52 PM
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Thanks. I will check the part number.

Is there a ground wire behind the radio for the temp gauge? The reason I ask is because the temp gauge stopped working after I changed the radio. Might be a coincidence.
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Old 04-01-2014, 06:46 PM
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OK, that sounds suspicious enough. The whole electrical system is a grounded system so I would say that every component in it shares the grounding in order to function. So it's possible that the radio work disrupted either the individual ground for the gauge or a 'group' ground that includes the gauge and other items.

At least you can access the radio work you did back there and still key the ignition on and off while you're back there. That will let you hunt down the connection that restores correct function to the gauge/sensor circuit and to whatever else may have had its grounding cut off. I guess I would start looking with the engine cold and look for the right 'cold' reading from the temp gauge when I key ignition to 'on.' Then I start engine and watch gauge move as temp rises.

Of course, if you can read the electrical schematic for that region, you are way ahead. And don't forget to check your fuses. Head unit installation work can blow stuff up..

Last edited by zxguy1986; 04-01-2014 at 08:42 PM.
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Old 04-02-2014, 09:36 AM
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Rule #1 when stuff stops working is :"what was the last thing I did!'
ground the wire you think is for the temp gage - it should pin out. if not you got the wrong wire. Also you made the common mistake of thinking someone on this forum is clairvoyant.
if you would really like answers that would help you and avoid flames give the following info when you post: year of car, n/a or turbo engine, stick or slushbox. Most of us can tell by the year what model you have ie 85T is a turbo z31. Z cars come in many flavors and they are all different. example 84,85,86 Z31's pretty comparable. there were changes in 87,88,89. in addition 300ZX can refer to two completly different cars the Z31 and the Z32. No mindreaders here the more info you can post the more likely you get a cogent useful answer
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Old 04-02-2014, 05:06 PM
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I thought I posted this in the Z32 tech forum? I agree i should have included make and model. Thanks for the flame.
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Old 04-02-2014, 05:44 PM
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No charge for the flame, dude! It's never personal here so don't take it that way.

When you think about it, this site is trying to cover ALL of the Zs from year one to the newest. Every year had multiple models because turbo/not, AT/5-speed, special editions. They are low/middle/high mileage now. Then owners can mod them in a way that makes a question about the orig model not apply anyway... and Z pros here can't figure out from the post what model applies to the question.

That's frustrating and doesn't help the poster because the Z pro who really knows the answer passes up the post because it is unclear - or gives the right answer to the wrong post, which is not his fault... and nobody wins.

We're looking for a solution. For now, the regulars here tend to blame the poster for assuming that the Z they own is the only Z the regulars here ever think about. Or that the regulars here are experts with all Zs ever produced. Not possible in any case. Unfair for posters to expect that. Or they're not thinking about this.

Until we find a site solution, your questions are always welcome and a challenge and exactly why we are here. Everybody learns. Whenever I post, I give enough info to put the Z pros exactly in my model, year, mileage, trans type, turbo/not, etc., everything they need to know to ignore every other model and think only about my Z - and then my question about it. Usually works. I get great responses doing it that way.

So keep up the good work! and thanks.

PS: We want to know what gives with your temp gauge...? Very interesting. A learning experience.

Last edited by zxguy1986; 04-02-2014 at 05:58 PM.
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Old 07-06-2016, 02:11 AM
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I am having same problem with my 93 z32

Hey since we are on same subject for Z32, I just bought mine and it is doing the same thing. Try to give as much info as I can. I start it in morning cold and it jumps right to middle of temp gauge when I turn key before starting. After starting it, it continually stays in the middle and idle starts to cut low and sometimes turns off, taking a long time to warm up. Even after warm up it hesitates and dies when shifting to neutral. Anything?
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