100 series keyless entry

Howdy. I recently bought a 100 series and it came with two Toyota single button 'beepers' for the doors.

Neither of them work.

I've replaced the battery in one and the light on the beeper flashes when I press the button, but nothing happens on the vehicle. I have read through the workshop manual extensively and can't find any reference to them in there.

I have checked all the spade type fuses under the bonnet and wiggled the relays etc but to no avail.

Any suggestions? Does anyone know where the receiver unit for this thing lives too?

Thanks in advance....