Temp gage not working
Thread Starter
Drifting
Joined: Jul 2005
Posts: 1,891
Likes: 2
From: Baltimore MD
I double checked the gage - never got it to beg when I grounded the sensor wire, but the gage needle does move. My temp reads about 186 or so never seems to get up to 200. What do other 81's run normally. I hate to tear into that center gage cluster again - but I guess I have to. Need to check a light bulb (spot light from the top of the cluster stopped working), and now this temp gage problem.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Did you have the key on? If grounding the sensor wire the gage doesnt go to full hot you have an issue with the gage or wiring going to the gage.Grounding and ungrounding the sensor wire must max your gauge both ways.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Roger, that would be the key. Its a shunt I think, different values for different temp senders. The problem is each gauge and each sender has a tolerence, I don't know what the window is on the components. But making the calibration resistor a variable, or wrapping a custom based on a measurement might be the way to go. One of the first cars I did was a 67 mustang, I re wound all the gauges so thay they were dead on, when the needle hit the center mark on the E you better be looking AT a gas pump
OK I went out and did some experimenting(i know too much free time) with different colored ceramic thingys.
Lt.Blue-123 ohms
Green--89 ohms ----green seems to be on 280* gauges
Yellow-88 ohms-----yellow seems to be on 260* "
Orange-86 ohms
Blue-Black-81 ohms
Stock 78 280* gage with green ceramic shunt on back of gage and a 68 ohm resistor on the sender wire to ground says 215-220 on the gage.
Same as above but with blue-black 81 shunt gage reads 210
" " " " " light-blue 123 shunt " " 260
So it looks like more resistance on the ground side of gauge raises temp.on gage but more resistance on the sender wire side lowers the temp.
Irishjoker did you put the ceramic shunt on left to right and not up and down?
Last edited by ...Roger...; Jun 25, 2007 at 05:16 PM. Reason: added in Orange and changed green fom 88 to 89 typo
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
Shunt what the heck is a shunt I thought that was used in football.
OK I went out and did some experimenting(i know too much free time) with different colored ceramic thingys.
Lt.Blue-123 ohms
Green--88 ohms ----green seems to be on 280* gauges
Yellow-88 ohms-----yellow seems to be on 260* "
Blue-Black-81 ohms
Stock 78 280* gage with green ceramic shunt on back of gage and a 68 ohm resistor on the sender wire to ground says 215-220 on the gage.
Same as above but with blue-black 81 shunt gage reads 210
" " " " " light-blue 123 shunt " " 260
So it looks like more resistance on the ground side of gauge raises temp.on gage but more resistance on the sender wire side lowers the temp.
Irishjoker did you put the ceramic shunt on left to right and not up and down?
OK I went out and did some experimenting(i know too much free time) with different colored ceramic thingys.
Lt.Blue-123 ohms
Green--88 ohms ----green seems to be on 280* gauges
Yellow-88 ohms-----yellow seems to be on 260* "
Blue-Black-81 ohms
Stock 78 280* gage with green ceramic shunt on back of gage and a 68 ohm resistor on the sender wire to ground says 215-220 on the gage.
Same as above but with blue-black 81 shunt gage reads 210
" " " " " light-blue 123 shunt " " 260
So it looks like more resistance on the ground side of gauge raises temp.on gage but more resistance on the sender wire side lowers the temp.
Irishjoker did you put the ceramic shunt on left to right and not up and down?
The general object would be to have whatever was calculated to be the normal operating temp be center gauge, some gauges have different ranges for whatever reason, but 1 sensor. SO different calibration resistors would allow centering the needle for normal operation.
Thread Starter
Drifting
Joined: Jul 2005
Posts: 1,891
Likes: 2
From: Baltimore MD
Shunt what the heck is a shunt I thought that was used in football.
OK I went out and did some experimenting(i know too much free time) with different colored ceramic thingys.
Lt.Blue-123 ohms
Green--88 ohms ----green seems to be on 280* gauges
Yellow-88 ohms-----yellow seems to be on 260* "
Blue-Black-81 ohms
Stock 78 280* gage with green ceramic shunt on back of gage and a 68 ohm resistor on the sender wire to ground says 215-220 on the gage.
Same as above but with blue-black 81 shunt gage reads 210
" " " " " light-blue 123 shunt " " 260
So it looks like more resistance on the ground side of gauge raises temp.on gage but more resistance on the sender wire side lowers the temp.
Irishjoker did you put the ceramic shunt on left to right and not up and down?
OK I went out and did some experimenting(i know too much free time) with different colored ceramic thingys.
Lt.Blue-123 ohms
Green--88 ohms ----green seems to be on 280* gauges
Yellow-88 ohms-----yellow seems to be on 260* "
Blue-Black-81 ohms
Stock 78 280* gage with green ceramic shunt on back of gage and a 68 ohm resistor on the sender wire to ground says 215-220 on the gage.
Same as above but with blue-black 81 shunt gage reads 210
" " " " " light-blue 123 shunt " " 260
So it looks like more resistance on the ground side of gauge raises temp.on gage but more resistance on the sender wire side lowers the temp.
Irishjoker did you put the ceramic shunt on left to right and not up and down?
What's normal for the temp?
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Thats about the results I would have thought. Are all those combinations meant to go with 1 sender or more than one?
The general object would be to have whatever was calculated to be the normal operating temp be center gauge, some gauges have different ranges for whatever reason, but 1 sensor. SO different calibration resistors would allow centering the needle for normal operation.
The general object would be to have whatever was calculated to be the normal operating temp be center gauge, some gauges have different ranges for whatever reason, but 1 sensor. SO different calibration resistors would allow centering the needle for normal operation.
The yellow and green are common on temp. gauges and the lt blue is generally found on a volt meter and the blue-black I usually find on oil pressure gauges.But I have found all of them on different gages over the years.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
Looking at the pics on Ecklers catalog there are about 5 different gauges, all but 1 have a center point of 210. If the 68 ohm test sets the gauge at 215 or so then that puts the needle just past the center point. Wouldn't have been my choice, but there it is. I like things a bit more precise than that. Heating up the temp sensor to 215 and measuring the resistance should produce a reading of approx 68 ohms. This will be a fun exercise. I wonder if the internals are the same for the diff temp gauges, must be.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
I have not opened up the back of the gage cluster at all - I never removed the circuit overlay - The gage is working now but I am not sure it's reading right - I never get up to 200 on the gage more like 189 or so and that's as far as the temp goes.
What's normal for the temp?
What's normal for the temp?
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