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Discussion Starter #1
I just swapped from standard SS gauges to tach optional gauges. So far tach works, amp gauge itself is just dead, and the temp gauge does not tell me the temp until the car gets shut off after running, and the fuel gauge doesn't work.

One question I have is why did my big fuel gauge require a resistor and the new one doesn't? I'd assume they work the exact same except for the smaller one being smaller. I'm wondering if the instructions or something left out adding a new resistor somewhere or something and that's why I see nothing. I tested the horizontal terminals with an ohm meter and volt meter, getting proper voltage and 144 ohms, don't know what that tells me.

I had to ground my temp gauge independently to get it to work, on the top terminal. Just ran a wire down to the e-brake assembly like another ground. It was staying all the way to the right and not reading until I tested grounding it. I recently read here in another post in the search that it should be grounded to the bottom terminal (I am referring to the terminals the resistors are on). If a different terminal is grounded, would that cause it to not read when running and then read with car off?

Thanks for helping
 

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If the fuel gauge is an original 71/72 fuel gauge it needs the resistor. It connects across the two side terminals.

The temp gauge ground needs to be connected to the bottom terminal. The top terminal grounds through the resistor to the bottom terminal. This pic show how the gauge should be connected.

If the green wire, from cluster connector to temp sender, is making contact with ground the gauge will peg to the right. Disconnect the wire from the temp sender and check for voltage. You should read battery voltage on the wire with it disconnected. With the green wire disconnected the gauge should be pegged to the left. With the green wire grounded the gauge should be pegged to the right.
 

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Discussion Starter #3
Thanks for the help. I just want to confirm, both temp gauge and fuel gauge need a resistor? I can pick one up easy, that's not a problem. They are aftermarket but they are original style meant to work with a printed circuit and original wiring, etc.

Thanks again!
 

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I have never worked with the reproduction gauges. They may or may not need the resistor. If it didn't come with one it likely doesn't need one. You may want to contact the supplier for that information.
 

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Discussion Starter #5
I just ran out and moved the ground to the bottom terminal. I didn't run the car very long but the needle was a bit over 100 when I started the car (and should be a bit warm because I just got home an hour ago from driving), so I'm going to go ahead and say bingo. Thanks!

I'll talk to who I got the gauges from, it was someone off eBay, not sure if he was selling some he had got or as a supplier. Need to talk to him anyway, my amp gauge doesn't work.

Can you recommend what kinds of stores sell resistors? Local Autozone and O'Reilly parts stores don't even carry them.

Thank you.
 

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My temp gauge is pegging out to the right too, maybe grounding that bottom terminal will help me out.

On mine the guage is a ways past the highest marking on the gauge and when connected it pegs out, it never falls down within the range of the gauge
 

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Discussion Starter #7
I contacted the guy I purchased the gauges from. Fuel gauge doesn't need a resistor. He said the top two reasons the fuel gauge doesn't work is either the bow connector isn't making contact with the circuit (doubt it), or that I mixed up wiring between the fuel gauge and the parking brake indicator. I believe it's that, because my parking brake pedal is broken so always sags, but now the light is not on now after the swap, and new fuel gauge isn't working. I think that would be too big of a coincidence. I'm trying to check, it looks like I should have a tan in slot 5 and a tan in slot 6 on my dash connector. I'll have to check what mine is and move stuff around.
 
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