The Fairway wasn’t fitted with an intercom as standard, so many were retrofitted with the Wolf kit (or similar) enabling drivers to easily communicate with passengers either side of the glass partition.
A taxi intercom will usually consist of a control box, a speaker and microphone for the drivers compartment, the same for the passenger area and some switches and lights to control it. The control box is situated in the central console in the drivers compartment, and now takes power from the bus bar which distributes 12v to various units (see my electronics overhaul page for more info).
The control box has all the inputs and outputs for the microphones and speakers, however to enable the system to be switched on and off from both the front and rear, a connector block and 2 SPDT switches are wired together (similar to a household lighting circuit with two switches). The LED indicator lights are wired in parallel with the switched 12v from the connector block.
In terms of audio quality, it’s not the best of systems but it does beat shouting through the partition. I changed the standard clip microphone which used to sit on top of the dashboard in the drivers compartment, to a gooseneck so it is held closer to the drivers mouth which makes for better clarity in the rear. There is only one microphone in the rear compartment which is mounted next to the left hand armrest and struggles to pick up quiet conversation. I have wired a headphone socket in parallel with the drivers speaker in order to hear passengers clearly on longer journeys.
To see more of the electrical work I have carried out you can take a look at the Electronics page.