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Old 08-23-2014, 02:25 PM   #4
Cluster King
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Join Date: Nov 2012
Location: Junction City, OR
Posts: 4,772
Re: 67-72 Chevy Truck fuel gauge diagnostics 101

In this set of photos, I will show the proper wiring from the gauge to the sending unit. Sorry about the wire colors for my test. For this I will use a green wire with alligator clips to simulate the tan wire and the yellow wire will be the ground. I also will use the + side of the battery charger as the 12V pink wire which comes from the ignition switch on the truck.

I then will show what happens to the gauge when I disconnect ground and power at the sender and the gauge.

As you can see, if the ground or tan wire become disconnected from the sending unit, it will make the gauge read at 3:00 (past full).

If you loose power from the ignition switch, the gauge will stay in its last known position with power.
Attached Images
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