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Low fuel light


New Member
Aug 26, 2023
Country Flag
Hi All,
Gmac here. I just joined. Hope I can find an answer to how to test my sub tank sender unit is operating properly. I recently put a long range tank in and all was working well until recently when the low fuel light came on.
I suspect it is this sender that may be the issue & the float is full of fuel & sitting on the bottom of the tank. When I disconnect the sender, my main dash gauge shows a change in the amount of fuel I have so I think the gauge is working to some point. If I disconnect the plug, how can I send a signal back to the dash gauge to see if the low level light goes out?
Hi Gmac,
I know the Toyota program Techstream can read individual fuel tank percentage levels.

Is the low fuel tank level light flashing or steady?

If you still have two tanks, there is a transfer system between tanks and if the auxiliary tank has a certain level of fuel (say 20%) and the main tank is close to empty the low fuel tank light will flash. The fuel level gauge will probably not be low as it looks at the total fuel of both tanks.

When you had the main tank replaced they should have fitted the original tank level and transfer pump system if the sub tank was still fitted.