Temp gauge
Thread Starter
Racer
Joined: Dec 2005
Posts: 344
Likes: 0
From: Washington DC
Temp gauge
I was driving in today on a nice, sunny Florida morning, when I looked down and noticed that my temp gauge was pointing straight down. Pulled over and popped the hood. Didnt feel especially hot. Car on or off, the needle points straight down. Think this is a connection somewhere or is the gauge shot?
Melting Slicks
Joined: Aug 2003
Posts: 2,135
Likes: 2
From: Dayton Oh
On my 79, the temp sensor is in the head between #1 & #3. Note that the wire to the sending unit is a ground wire, not a hot wire, and the hotter the engine then the more ground is sent to the temp guage. To check, disconnect the wire from the sensor and then ground the wire with the key on. Your temp guage should peg out in the hot range. I can't tell from your description if your guage is reading way low or way hi. If it is pegged way lo, then grounding the wire should cause the needle to move. If so then the sending unit is bad. If the guage is already pegged way hi, then probably the wire from the sending unit to the guage has shorted out against something.
Melting Slicks
Joined: Sep 2004
Posts: 2,412
Likes: 3
Originally Posted by marshrat99
On my 79, the temp sensor is in the head between #1 & #3. Note that the wire to the sending unit is a ground wire, not a hot wire, and the hotter the engine then the more ground is sent to the temp guage. To check, disconnect the wire from the sensor and then ground the wire with the key on. Your temp guage should peg out in the hot range. I can't tell from your description if your guage is reading way low or way hi. If it is pegged way lo, then grounding the wire should cause the needle to move. If so then the sending unit is bad. If the guage is already pegged way hi, then probably the wire from the sending unit to the guage has shorted out against something.
My temp sensor has done this before. Before you start investing time diagnosing, I would just replace it, and see if that fixes the problem.
Normally the sensor is screwed into the head, but some people, like myself have relocated it to the intake manifold.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
that sensor is on the ground side of the guage, grounding the wire will give you some meter deflection. Mad has a section on calibrating your temp sensore, look on there to see how to test the sensore, it involves heating up the sensor up in a pan of water while measureing the resistance on the sensor, simple actually.
Thread Starter
Racer
Joined: Dec 2005
Posts: 344
Likes: 0
From: Washington DC
Originally Posted by marshrat99
On my 79, the temp sensor is in the head between #1 & #3. Note that the wire to the sending unit is a ground wire, not a hot wire, and the hotter the engine then the more ground is sent to the temp guage. To check, disconnect the wire from the sensor and then ground the wire with the key on. Your temp guage should peg out in the hot range. I can't tell from your description if your guage is reading way low or way hi. If it is pegged way lo, then grounding the wire should cause the needle to move. If so then the sending unit is bad. If the guage is already pegged way hi, then probably the wire from the sending unit to the guage has shorted out against something.
Thread Starter
Racer
Joined: Dec 2005
Posts: 344
Likes: 0
From: Washington DC
Sorry, I should have been more specific...I have a 69. The intake is off of a 67 Camaro 327. Pretty sure the plug in the intake toward the front on the drivers side with the wire coming out of it is the temp sensor.
So, based on what I have read here, the question is, can I assume the gauge is shot if the needle is pointing at 5 o'clock or is that a position that could be caused by an electrical problem?
Thanks
So, based on what I have read here, the question is, can I assume the gauge is shot if the needle is pointing at 5 o'clock or is that a position that could be caused by an electrical problem?
Thanks
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Melting Slicks
Joined: Jun 2003
Posts: 2,802
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From: Niles, MI
Last edited by Kid Vette; Apr 4, 2006 at 03:01 PM.
Thread Starter
Racer
Joined: Dec 2005
Posts: 344
Likes: 0
From: Washington DC
Update
After doing all the tests outside instrument panel, I determined that it had to be something in that panel. Finally built up the will to tear into it and found that the wiring harness on the back of the temp gauge had come off. Not sure how something like that works itself off the prongs, but that was the problem. Plugged it back in and the needle jumped to life. Just glad it wasnt a bad guage or worse, a bad wire.
Thanks for the help...
Thanks for the help...
