Hi Guys,

I’m looking for some advice from the auto electricians amongst you. I’ve fitted an auxiliary tank to my Toyota Landcruiser, and I’m trying to wire up the main and auxiliary sender units to a dash mounted switch, in order to read the contents of the tanks on the same gauge. The main tank has three wires. One goes to an earth on the tank. one to the float, and one to the low level warning light on the sender.

The auxiliary sender has two wires. I presumed that I could take the power supply to the main sender unit, run it through a switching relay, and switch between the two tanks. I’ve tried to jury rig everything together prior to fitting, but it doesn’t work. Electrics are not my strong point, and I’d be grateful to any of you for some advice on how to go about this.

Regards, Ian.

Not sure of the pin numbers off the top of my head..

You would want the single wire coming out of the Relay going to the Guage

And the Normaly closed contact going to the original sender signal wire

And the Normally Open contact going to the New sender

First things first. Is the sender unit in the aux tank compatible with the standard fuel gauge?

one of the wires on the new tank would be an earth; you can common both sender earths together, then the relay wired as above.

Thanks for the replies. The senders are compatible, as it's an auxiliary tank designed and made by Toyota as an optional extra. I thought I'd sorted out the relay wiring, until I read your post MkIndy7! I think you've hit the nail on the head. I've messed up on the single wire to the gauge.

Many thanks, Ian.