North America 1972-73:
North America 1974: More information on this system can be found here
North America 1975-on:
Note: To starter and brake warning circuits.
The 'time delay unit' seems to flash the warning lamp on and off (maybe only after the ignition key as been turned to 'START' otherwise I can't see the point of that connection) until the seat-belt is fastened or the ignition is turned off. The module should be behind the centre console.