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coolant gauge got me frazzled by EvilSqueezles
Started on: 09-04-2013 03:44 PM
Replies: 8 (141 views)
Last post by: EvilSqueezles on 09-04-2013 09:07 PM
EvilSqueezles
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Report this Post09-04-2013 03:44 PM Click Here to See the Profile for EvilSqueezlesClick Here to Email EvilSqueezlesSend a Private Message to EvilSqueezlesEdit/Delete MessageReply w/QuoteDirect Link to This Post
2.8 stock v6 auto

OK. When i bought the car someone had done the ole wiring switcheroo to stop the temp gauge from pinging at ignition. But at the same time the speedometer wasn't working. Turned out to be a wire that had come undone in that wiring swap. OK so I out the wires back to normal routing... thinking that would solve both issues. Yea, it didn't. It instead gave me a working speedometer but without a working temp gauge. So I took it back out and redid the wire swap but made sure the wires couldn't come loose again. I still have a working speedometer, but my temp gauge still doesn't rise. It will flicker a little at ignition as it should, so it seems to me to be getting power.

So. I swapped the coolant temp sensor out with another. Still doesn't rise. I took the 160° thermostat completely out. Still doesn't rise.

I've tried checking resistance through the sensor but must be doing it wrong. With my voltmeter set at 20k ohms it reads 1. which is what it reads even when not connected to anything. I've tried touching the blades with both leads and then swapped leads to opposite blades but no change. Am I doing this wrong? I was gonna best it with a lighter to see if it changed but I can never get a reading to begin with.

Also, my radiator fan is on at all times if the ignition is turned on. I put in a new switch thinking it may be faulty but that didn't change anything either. I just noticed that under the driver side by the headlight harness a 4 flat connector. Two of the wires here are tied together with one of those crimp blue connectors a few inches back from the connector. Its the small black/grey wire and the larger black/red wire. Is this what is causing my fan to be on constantly? I don't know. I've fixed 95% of this car but not having a temp gauge in a fiero in my opinion is just asking for trouble. Is there a good electrical alternative to the factory gauge? Or does this seem like a rather easy fix and I'm just dumbfounded by it?
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trotterlg
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Report this Post09-04-2013 03:55 PM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
The coolant sensor has two functions, one is the gauge and the other is the high temp light. One blade is the switch, open or closed that turns on the light (closes to ground), the other blade is the temp sender which is a resistance to ground, so both are using the ground path for return. Between the two there should be no path. Larry
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EvilSqueezles
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Report this Post09-04-2013 03:58 PM Click Here to See the Profile for EvilSqueezlesClick Here to Email EvilSqueezlesSend a Private Message to EvilSqueezlesEdit/Delete MessageReply w/QuoteDirect Link to This Post
Yea I was being stupid. I just check the one I removed, at with my meter at 20k I'm getting a 1.91 reading. After holding a light to it it dropped to 0.34. Seems to me that the sensor is working properly? As resistance drops the gauge should rise but its not. Any other ideas? Should I double check these wires? There are 2 green wires, one has a yellow stripe. Anyone know which wire goes to the gauge? I know which blade does now.
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trotterlg
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Report this Post09-04-2013 04:06 PM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
On the Fiero when the temp get hotter the resistance goes down and the gauge goes up. Larry
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EvilSqueezles
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Report this Post09-04-2013 04:28 PM Click Here to See the Profile for EvilSqueezlesClick Here to Email EvilSqueezlesSend a Private Message to EvilSqueezlesEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thought that's what I said. Oh well. Anyways..

I switched the sensors out again, tested before and got 1.91. After running the car the resistance dropped to 0.64, which should indicate that the gauge should rise. However it doesn't still. I'm stifled. Quite honestly. I know the right wire is plugged in on the right blade. The one that has voltage coming to it should be on the gauge blade correct?

The other has no voltage so I assume that when it gets "oh **** hot" that it opens the sensor and sends voltage through to the light.

The gauge worked properly before I put the wires back together. But all i did was put real connections on them instead of twist n tape. So I don't see how it could be in the wiring panel wise. And as i stated previously, the gauge does jump up to almost 100 as per normal when I turn the ignition. Any ideas? Am I just overlooking something?

By the wah, the wire that goes to the gauge is showing 12.5 volts, is that normal or high?

[This message has been edited by EvilSqueezles (edited 09-04-2013).]

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trotterlg
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Report this Post09-04-2013 04:49 PM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
Both should have voltage to them, when you ground one the light comes on and when you ground the other the temp needle pegs hot, take care that if you try this you may stick the needle in the pegged postition. Larry
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EvilSqueezles
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Report this Post09-04-2013 06:10 PM Click Here to See the Profile for EvilSqueezlesClick Here to Email EvilSqueezlesSend a Private Message to EvilSqueezlesEdit/Delete MessageReply w/QuoteDirect Link to This Post
All fixed. You know its funny how easily something gets messed up JUST ENOUGH on these cars to make you think the whole system is going out. The harness that plugs into the back of the instrument panel has wire ends on the plug harness that "arc" up to squeeze in and make good contact. One of these was flattened out. Problem fixed.....

I wanna know if anyone knows more about this radiator fan thing though. Also, while I'm at it... theres a relay in the front driver side headlight bay. I have nothing going to it, any ideas what that would be? Also does anyone know if those wires being crossed on that plug as I mentioned before would be for the fan? It almost looks like to me that someone unplugged that relay and jumpered those 2 wires to purposely run the fan at all time. I conclude this because when I did the motor exchange the cooling fan switch wire harness was broken to high hell. So I'm guessing they just jumpered those together instead of fixing the real problem. Or the relay went bad, either way.

AND, becuase I'm a pain. Currently, after I let the car sit idle for about 10 minutes. It only read a temp of about 115 degrees. Now keep in mind the fan is constantly on, and that was with no thermostat installed. Sound outrageous or at least close? With an open system and constant fan it didnt surprise me but I figured I'd better cross check myself. Thank you!
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trotterlg
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Report this Post09-04-2013 07:27 PM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
The relay in front of the healight would be the radiator fan relay. Larry
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EvilSqueezles
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Report this Post09-04-2013 09:07 PM Click Here to See the Profile for EvilSqueezlesClick Here to Email EvilSqueezlesSend a Private Message to EvilSqueezlesEdit/Delete MessageReply w/QuoteDirect Link to This Post
Awesome that's where I was leaning. So yes it is unplugged completely and 2 wires are jumped to keep the fan on all the time. Gonna have to remedy that. Thank you much sir. + for you

------------------
~James

87 GT (Under Construction)

Madarch Widebody, Kahines tail, 3800SCII.... gonna be fun making threads on those!

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