78 temp gauge
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,852
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
No I don't think the sender is the problem yet. The 700 cold is possible. I would rather have a reading when the car was 180 or so. . . but lets look at the face first and see what you have going on. Below this picture might help you Id the problem. The needle position my vary per year but it should be pretty close.
If the needle is buried to the right and sitting on or real near the rivet, the ohms wire is grounded out and still attached to the gauge. (shorted)
If it is buried past the rivet, you have ohms, you have power and you do not have a ground.
Willcox
18243
If the needle is buried to the right and sitting on or real near the rivet, the ohms wire is grounded out and still attached to the gauge. (shorted)
If it is buried past the rivet, you have ohms, you have power and you do not have a ground.
Willcox
18243
Last edited by Willcox Corvette; Feb 7, 2010 at 04:08 PM.
Thread Starter
Intermediate
Joined: Jun 2008
Posts: 33
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No I don't think the sender is the problem yet. The 700 cold is possible. I would rather have a reading when the car was 180 or so. . . but lets look at the face first and see what you have going on. Below this picture might help you Id the problem. The needle position my vary per year but it should be pretty close.
If the needle is buried to the right and sitting on or real near the rivet, the ohms wire is grounded out and still attached to the gauge. (shorted)
If it is buried past the rivet, you have ohms, you have power and you do not have a ground.
Willcox
If the needle is buried to the right and sitting on or real near the rivet, the ohms wire is grounded out and still attached to the gauge. (shorted)
If it is buried past the rivet, you have ohms, you have power and you do not have a ground.
Willcox
Its the middle one... what do I do, or what am I doing wrong..
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Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
Can't remember or not have you tried testing the gauge independent of the cars wiring ? If not do that next and confirm that the needle will go to cold when the ohms input stud is ungrounded and that the needle will go to hot when grounded.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,852
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
To do this take the gauge out of the housing, run 12 volts to the number 12 stud shown in my picture above, run a ground to the 3 o’clock stud. Just like in the picture above the needle should get real close to the picture on the left.
Then add ohms from the sending unit in the car to the 6 o'clock stud and remove the ground. The gauge should look like the one in the middle.
With the ohms added and the power and hot connected, the gauge should read in relation to the ohms from the sender. So if you run the car for a while and heat it up you should see movement in the gauge.
This should test should confirm a good dash unit or not. If it's bad let me know, I think I have a good used one.
Willcox
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,852
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
I wanted to add to this for you guys, if the resistor is bad on the back of the gauge, it will act just like the middle gauge in our picture. A gauge with power, and input but no ground.
Willcox
Willcox
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Hmmm I thought when the resistor was bad or not installed it did the 1/2 needle swing thing. Its too late to go out to the garage and test it. I'm not going to do it. Guess I should have written it down when we were testing gauges. Maybe I'm thinking about the fuel gauge. I'm not going out there.
Thread Starter
Intermediate
Joined: Jun 2008
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Very interesting, when I test the gauge i dont get any movement at all or hardly when i connect the power and ground up and the input. However it did look very simular to the one in the middle. anyway the one thing I noticed thou as everytime I grounded the input wire it went off to the bottom of the gauge everytime which is what it does in the car soon as i turn the ignitition on.
Thread Starter
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I am thinking tonight that when the gauge is in the cluster to cut the input wire and see if it goes up as what I beleive is wrong with it is the input wire is earthing out either on the sender unit or somewhere on the line somewhere which is making the gauge do what it does.. will post tonight on outcome
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,852
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
If you pulled the gauge out of the car, ran ground, power, and left off the input wire it should only peg to the rivet as shown above. If it went to the bottom, you probably have a defective gauge. Why don't you mail this gauge to me and I'll test it for you. . . No charge... Then you'll know for sure and it only takes me about 2 minutes to check it.
Willcox
Willcox
Thread Starter
Intermediate
Joined: Jun 2008
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Also with the battery gauge, does it only come up when you start the car, not with ignition on. I have seen the gauge work once and for some reason now it doesnt work. Am i suppose to put washes on the back as the lights work and i have power so it must be a connection problem with the Battery Gauge
