Malfunctioning gas gauge

Scottdan

Even though gas tank is full, needle is reading empty.

Mr_Shiftright

You'll have to test to see if the sending unit is operating properly and if so, they you'll have to test at the gauge cluster. These tests require a wiring diagram, a VOM meter and, of course, the mechanical knowledge. So the possibilities are sending unit, gauge itself or wiring to and fro. Checking the sending unit will properly require dropping the gas tank.

Here's a discussion that explains how to do it but this is for a 2002 model, so I wouldn't use their wiring diagram.

https://www.justanswer.com/toyota/af6cy-fuel-gauge-dte-not-working-sequoia-fuel-sending-unit.html