LED 12V switch

Wire +12V to pin 1, pin 2 then goes to the pump but you also link it to the + LED connection and the - goes to the earth. This is assuming that the LED is designed to be used on 12V and it already has a resistor built into the LED part of the switch.

If you need a resistor, 860 ohms in series should be fine, you could put the resister between pin 2 and LED +.

Jerry
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Your earth wire goes to the dull looking pin. Without earth the led will not work. Then the + wire and wire to the pump goes to the other 2 pins.