Hi I need a little help here, I have a 2001 au3 falcon sedan with gas but no way of telling how much gas is in the tank, unless I open the boot and stick my head in but that is a PITA as the tank is mounted so that the guage is nearly facing the parcel shelf the only wires running to the tank are for the cut off valve.

so what I need is a simple digram showing how to wire the sender to the lpg switch??if it needs to and into the petrol level sender as I don't want the led guage (and dont have one anyway) The car is an ex taxi and probably had it wired before but when it was decommisioned they did a motor swap for one with 170000ks so they played with all the wires I've only just sorted the gastec fp30 controller wireing.

any help much appreciated thanks

The sender on the gas tank needs to have the same resistance as the petrol sender.
Then it's just a matter of a change over relay.

Personly I'd just fit an Apexus PG200 switch. They are small, neat and reliable.

the tank sender is 0-174ohm but my problem is no wires from the switch to the tank for the sender.

I was thinking of running a wire fromthe cutoff to a relay that would switch between the sender from petrol to the sender for gas kinda like this



Excuse the MsPaint

so going by this when the relay has no power it shows what the petrol sender sends as I would tap into the signal wire and have the side from the tank connected to nomily closed and the side from the cluster connected to the common pin.

When the relay is powered from powering the cutoff actuator then the signal from the gas tank sender would be sent to the cluster.

how would I tell what impedance the petrol sender has?
and would one of the gas sender wires go to ground?

Cheers

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slept on the problem last night.

And realised i would need a DPST relay as both wires from each sender need to go to the guage.

so here is a pic of what i have planned



Do i need to workout the guage impediance? or can i just go by the petrol sender impediance?

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wired it up as per the second diagram and it seems to work well

ok discovered a problem when the relay switches it won update the fuel guage untill you turn the car off then on any ideas?

it's because the car is smart enough to know that large changes in level don't happen instantly.

What happen if you change it over and just keep driving the car for 10 mins?

i would try that but it needs a gas tune and new converter as it is weeping coolant from the rear seal i know with some factory setups the guage changes instantly would they have it switching after the ecu for that to happen?