LED and Contents Gauge Wiring.
The GAS IT 9 LED content gauges and tank sender unit works by sending a resistive signal from the float indicator in the tank (where the 0-95 ohm sender is installed), upto the LED indicator in the vehicle.
The LED indicator itself is designed to work on 12 volts DC and we advise some kind of switch supply is provided so that the LED's don't drain the vehicles battery over time. When installing and wiring up the LED display we always recommend that you fit a small 1 to 3 amp fuse inline with the 12 volt to the LED.
When you first connect the LED gauge, if there is no sender unit in the tank wired to the LED display, all the LEDs will light up to show the tank is full. This is a safety design feature we implimented many years ago so should there be a break in the wire from the tank sender or a bad earth, the LED would show full and not empty as we were concerned that if the LED to failed empty people would force gas into an already full tank and over fill it whihc causes more issues than them simply running out of gas, so this way with our safety design feature, if the wires break or the earth fails then it goes to full and people run out of gas only.
When wiring the tank 0-95 ohm sender to the 9 LED gauge you must run 2 wires directly from the tank sender (from the green and black wire) up to where you have the led gauge installed At some point along that black wire you need to earth the 9 LED and tank sender wires on its own good quality earth point and not join it to any other earths,this is because the signal from the tank to the gauge is resistive and other earths can cause this signal to vary. ( We always advise earthing the black wire inside the vehicle and not externally to stop any issues in the future due to corrosion.)
Once you have wired the sender to the LED gauge and before you fix the sender into the tank with the 2 small Phillips screws ( DO NOT REMOVE THE 4 ALLEN BOLTS holding the actual brass sender valve into the tank because the sender unit is held to the tank with 2 very small Phillips screws only ) , we advise putting a magnet or metal screwdriver on the back of the tank sender gauge and move the sender round from where it is to empty and look at the LED gauge to make sure it goes down to empty. Once your happy, move the gauge round to full and check the LED goes to full. there will be some delay in the LED's moving from full to empty as we have a damping circuit built into the Led gauge so it doesn't go full to empty when the LPG in the gas tanks sloshes when going round corners.
Please note that the magnet in the sender unit at some point has to pick up the magnet in the tanks float valve unit for it to start reading correctly ( start moving ), so depending where the sender unit has been left on assembly they might not align until the float level valve next goes past the gauge which could be when going from full to empty or empty to full. Once the magnets are aligned they will stay aligned.
See the attached GAS IT Gauge and sender wiring diagram for more information.