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Old 05-18-2016, 04:05 PM   #1
FJC
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Default Gauge Problems

So I recently bought my 69 Corvette and I couldn't help myself but to fix all of the gauges in the gauge cluster which didn't work when I bought the car. For reasons which elude me the last owner (who owned it for 6 months) wired the temperature sending wire to the electric choke and thus left me with a temperature gauge which he said "works" though neglected to tell me it isn't connected to ANYTHING. So, once I found that I started tracing wires which then led me to disassemble the dash and whatnot. Thanks to all of the informative threads, I have been able to work my way through most of the issues. I pulled the entire gauge cluster and bought a potentiometer to test the gauges and to my pleasant surprise they all worked. Then I started looking at the gauge wiring itself... everything was backwards or rigged poorly but nothing worked. I have spent the past week whenever I have had free time and wired the electric choke correctly to the fuse box with an inline fuse and ran it through the firewall then went to work behind the dash and tried to find the other gremlins as they came up.

I have been able correctly rewire the temperature gauge and cleared the blocked oil pressure gauge but am having an issue with the fuel gauge. After looking into it further I found that the resistor in place is a camaro shunt fuel gauge resister. It has a resistance of 84 ohms. The question I have is do I need to replace this or will it work? I realize it's best to replace it but will this (mostly) be accurate with a difference of 6 ohms. Also it has no insulator... do I need to find an insulator for this shunt resistor or is it already insulated due because it's ceramic?

I checked the ohms from the sending unit and the wire going to the gauge, both are reading around 66 ohms but the unit is saying only 1/4 full. It is at the 1/4 mark not above which from what I have read does not indicate a blown resistor.

Thanks for any help.

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Old 05-18-2016, 05:56 PM   #2
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This is the correct resistor:


https://willcoxcorvette.com/corvette...tor-used-68-76

I have some original resistors left but the ceramic resistor you have is reading 87 ohms you'll be fine. The original resistor was 90 ohms so you'll be a tad bit off but not by much. You won't need to insulate the ceramic resistor, but you will need the black insulator down first as pictured below. When you tighten up the nuts you'll make contact, so I'd just install it like the original below and test it before you install it. Test it by adding ground and power to the gauge first then look at the gauge it should read full. Then ground the ohms stud to the ground stud and the gauge should go empty. (as shown below)

Now.. you could also make a needle adjustment while you are doing to this to offset the ohm different in the resistor... if you look at the position of the needle when it's grounded out... and if your needle isn't like that... pull it off and re-set it to look just like the picture below.





Willcox

Last edited by Willcox Corvette; 05-18-2016 at 06:01 PM.
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Old 05-18-2016, 06:29 PM   #3
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Ok, that's kinda what I thought. I don't have the insulator for that so I may try to use some insulating washers over nuts as a spacer. BTW thank you for the help guide, I have used them every step of the way while doing this. Wish the PO had done the same!!

Last edited by FJC; 05-18-2016 at 06:29 PM.
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Old 05-18-2016, 11:15 PM   #4
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Quote:
Originally Posted by fjc1982 View Post
Ok, that's kinda what I thought. I don't have the insulator for that so I may try to use some insulating washers over nuts as a spacer. BTW thank you for the help guide, I have used them every step of the way while doing this. Wish the PO had done the same!!
My pleasure!

I have the correct used insulators in stock if you need one.. they are 7.00.

They are not on the site but you can order one by calling sales at 812-288-7103 tomorrow.

You could make one too.. but the insulators are also what determines and holds the position of the terminals and prevents the studs from grounding out on the case... so you might be better off just getting one.

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