Go to Jaycar or Dick smiths and buy a 12 volt reversing beeper. Its about the size of a 50 cent piece, 10mm thick and circular.
It has 2 thin wires.
find the blinker repeater module under the dash and pull the connector apart.
Insert the wires into the holes until it beeps when indicator is activated.
Not both wires into same hole though...
You will find that it is loud enough to be heard above the roar of the engine , even with the hood down. So bobs you uncle....
