I am having trouble reading my fuel and temp gauge they don't seem to be working. I have notice little white tape w/ wire wraped around them. I was told they are gauge resistors. Would changing them solve my problem? Where can I buy new ones? If I were to test them on a multimeter, what should the ohms, resistance, etc. read? Please Help!
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Re: Gauge resistors
Hi Roberto:
At least for the temp gauge, I think the resistor was installed as part of the factory calibration process. Various resistor values were used to trim the meter readings to reduce unit-to-unit variations in production.
Others on this board will likely know more, but I doubt that the resistors themselves are likely to fail. You may have electrical problems outside of the gauges, or perhaps the gauges have developed internal problems and need to be replaced.
Be sure to do some testing to eliminate outside causes before you pull the cluster to replace gauges. It's pretty easy to test the temp gauge, and I think this has been discussed in the archives. The meter reading should be driven to the two extremes as you alternately open and ground the connection to the sender.
The fuel gauge is a bit tricky to diagnose, but John Hinckley wrote a nice article on the subject last year in Corvette Enthusiast. I can mail you a copy if you like. -
Re: Gauge resistors
Oops, just checked your profile and I see that your car is a 73. My responses were for a midyear. The temp gauge info is likely the same, but I think the 73 fuel gauge was much simpler to diagnose than the midyear version. I believe the gauge simply responds to the resistance-to-ground created by the tank sender, probably in the range of roughly 0 to 100 ohms. Others who know more about C3s can probably provide more details.Comment
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Re: Gauge resistors
Joe is correct, the 'flat pack' wire wound resistors installed on the back of gauges are t******* resistors that were hand selected at the factory to force each guage to read accurately. There is no source I know of for replacement, plus you'd have to duplicate the factory original gauge calibration fixture to define the proper value for the resistor(s) used on your gauge(s)....
Essentially, they provide a 'shunt' current path across the gauge to force it to read accurately. Earlier gauges were calibrated by connecting the assembled gauge to a calibration station and then installing the pointer needle onto the shaft in a specific orientation.Comment
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Re: Gauge resistors
Yes, can you please email me the article by John Hinckley? Thanks.Comment
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