The wire from the bottle on the B&G kit goes through the grommet (next to the engine bay inspection cover) on the passenger side into the car and then under the T-bar where the ECU and buzzer is fitted. Another set of wires run down the centre consol for power and the warning light.
Took a look at the above link. It seems a good wiring circuit but a little too complicated. I don't think that a timer relay is nessasary. Anyone know how to wire just a LED, Buzzer and the Coolant tank sensor?
Presumably there is a float in the tank (unlike the B&G version) and when the tank is full the float breaks the circuit? You will need a voltage supply to the tank with a feed coming back with a 560-ohm resistor in series with a LED.