Temp gauge reads wrong?!?

DK832

New Member

Apr 11, 2006

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Copenhagen, DK

Jun 9, 2009

#1

• Jun 9, 2009

• #1

Ran out of things to try: I've swapped a water temp gauge for an Autometer electrical one, sensor sits in the intake as usual. Ran wires to +12V ignition lead in the plug to the dash/gauges, ground to point behind dash, dash lighting and used the old original wire out to the sensor in the intake. When I use an IR temp gun the intake/sensor is 63°F but the gauge shows 150°F! When running at normal temp the gauge shows 250°F... I have tried 2 new Autometer sensors and 1 old used one (not Autometer), all have this misreading. I could find and add a resistor of (say 0.5 ohms) to the sensor wire to correct but WTF is going wrong here? Bad gauge or have I missed something entirely?

 

D

D.Hearne

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Sep 29, 2000

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south louisiana

Jun 9, 2009

#2

• Jun 9, 2009

• #2

Why'd you use the old wiring ? That could well be the problem.

 

DK832

New Member

Apr 11, 2006

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Copenhagen, DK

Jun 10, 2009

#3

• Jun 10, 2009

• #3

Thanks for the input. Yeah, one of the first things I checked. Reused so I wouldn't have to open up the wire harness in the engine bay. It's fairly nice as it is. I measured the old wiring and it has the same resistance as a similar piece of new wire. The sensor has lower resistance as it gets hotter, so if anything the old wire should have the gauge showing too little.

 

1

10secgoal

Active Member

Dec 1, 2003

2,801

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San Diego

Jun 10, 2009

#4

• Jun 10, 2009

• #4

Did you have the problem before the new gauge ? Because the autometer and other after market gauges use a GM ohm sensor. That and auto meter sensors go out all the time, if you have one of those in there. Did you use teflon tape, or over tighten ?

 

DK832

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Apr 11, 2006

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Copenhagen, DK

Jun 11, 2009

#5

• Jun 11, 2009

• #5

No problems b4, Autometer in there now, even tried a new Autometer too. And yes, I used teflon tape...?

 

1

10secgoal

Active Member

Dec 1, 2003

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San Diego

Jun 11, 2009

#6

• Jun 11, 2009

• #6

Eh, can sometime have them read funny if the teflon blocks the ground. We use teflon paste for it. Did you have a sensor that came with it, or the stocker ? Think 99% of their stuff is GM ohm sensors

 

DK832

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Apr 11, 2006

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Copenhagen, DK

Jun 12, 2009

#7

• Jun 12, 2009

• #7

Ok, will try paste. The sensor came with it but I also tried a N.I.B. I had on the shelf. Also tried the original one that was on the old gauge (not Autometer). All show approx the same fault. I might try to borrow a second gauge to see if its just faulty...

 

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10secgoal

Active Member

Dec 1, 2003

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San Diego

Jun 12, 2009

#8

• Jun 12, 2009

• #8

They can get all fubar also if they are overtightened.