Ford TRANSIT CUSTOM Owner's Manual page 85

Seats
The maximum temperature is reached
after five or six minutes. It is regulated
thermostatically.
The heated seat will remain on until you
switch it off. If the heated seat is on when
you switch the ignition off, it will be on
when you switch the ignition back on.
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Transit Custom (TTF) Vehicles Built From: 14-01-2013