Fuel Sender unit - 12v and 24v - does it matter?

Submitted: Monday, Mar 14, 2005 at 23:49
ThreadID: 21228 Views:7294 Replies:4 FollowUps:3
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One for the electrically informed.

My question is whether a fuel sender unit is voltage dependent. i.e. will it work on a 24v system if it has come from a 12v system?

My guess is that it will be fine as the sender unit appears to be a chunky variable resistor, which in my limited electronics experience are not linked to a critical voltage – unlike a lamp which has a relatively tight voltage tolerance.

The scenario is that I have an HJ61 grey import running 24v electrics.
I have installed a second hand Opposite Lock Aux fuel tank, which contains a fuel sender from an FJ60 – I am assuming this came from a 12v vehicle.

I want to connect the aux tank sender unit to the main dash fuel gauge via a switch the same as normal aux tanks are set up.

As a test before I installed everything, I disconnected the plug from the main tank fuel sender and plugged in the aux tank sender unit. The dash fuel gauge appeared to function as it should – that is showing full, half full and empty when the sender unit arm was in the corresponding positions. The sender unit did not get hot or blow any fuses etc! so I am figuring it will be okay to mount permanently like this.

When I tested the voltage at the lead to the fuel gauge, it was very low, almost zero – i.e not 24v or 12v, so this confirmed my theory about the sender unit being okay across 24v and 12v vehicles.

Does anyone else have an opinion on whether my assumptions are reasonable and this will work okay? Or alternatives if necessary?

Thanks
Tim

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