68 fuel gauge

[vectorit]

There is only a single lite brown wire that runs front to back for the sending unit, it has a clip style connector that connects to the sending unit and has a plastic cover. Often times this connector loses it's connection, and can cause wacky behavior on the gauge.
There is a black wire that comes off the sending unit, and that one is bolted to the chassis for ground.

For the front fuse block, I don't remember anything had to be connected. Since it is all handled by the harness that comes down the A pillar, and has a big plug that connects to the fuse block.

Have someone watch the gauge as you move the wires on the sending unit with a wooden dowel, you can do this from the passenger rear wheel well.
Careful of the brown wire connection, like I said it's kind of a fragile connector.

[LockDoc]

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You might try testing the continuity in the light brown wire from the under dash connector to the connector by the drivers side tail light. If your truck has interior panels you will have to remove the rear drivers side one to get to the connector... Also check where the wire loom goes around the emergency brake assembly under the dash. My emergency brake ratchet plate was rubbing on my wiring. (this won't apply if you are talking about the '68)

LockDoc