Front Seat Heaters

WARNING: This page is about a different car, the 2012 Land Rover Range Rover Sport and 2011 Land Rover Range Rover Sport. However, it is still accessible from the selected car via links, so may be relevant.

The front seat heaters are enabled when Power mode 6 engaged, and operate at one of two temperature settings. With the first press of a front seat heater switch the automatic temperature control (ATC) module adopts the higher temperature setting, supplies a power feed to the related front seat heater elements and illuminates two amber light emitting diode (LED)s in the switch. At the second press of the switch the automatic temperature control (ATC) module adopts the lower temperature setting and extinguishes one of the light emitting diode (LED)s. At the third press of the switch the automatic temperature control (ATC) module de-energizes the heater elements and extinguishes the second light emitting diode (LED). The seat heaters remain on until selected off or the engine is turned off.

The automatic temperature control (ATC) module receives an input from a temperature sensor in each front seat, and regulates the power feed of the heater elements to control the seat temperature at the appropriate temperature setting between 35 and 45°C (95 and 113°F). The actual temperature settings vary with the type of seat covering, to allow for the different heat conduction properties of the different materials.

When the front seat heaters are activated at the higher temperature setting, the automatic temperature control (ATC) module automatically resets them to the lower temperature after a time delay. The length of the time delay depends on the in-vehicle temperature.

TEMPERATURE RESET TIME DELAY

In-vehicle Temperature,°C (°F)	<-15 (5)	-15 to -10 (5 to 14)	-10 to 0 (14 to 32)	0 to 15 (32 to 59)	15 to 25 (59 to 77)	>25 (77)
Time Delay, minutes	Remains at higher temperature until manually de-selected	20	15	10	5	3

To protect the heater elements, the automatic temperature control (ATC) module disables front seat heating if battery voltage exceeds 16.5 ± 0.3 V for more than 5 seconds. Front seat heating is re-enabled when battery voltage decreases to 16.2 ± 0.3 V.

The automatic temperature control (ATC) module monitors the power feeds to the heater elements and disables the applicable front seat heating if a short or open circuit is detected. The automatic temperature control (ATC) module also disables seat heating if the seat temperature rises significantly above the target temperature setting.

The plausibility of the temperature sensor inputs is also monitored by the automatic temperature control (ATC) module. When seat heating is selected, if one of the temperature sensor inputs is within 5°C (9°F) below the target temperature, the automatic temperature control (ATC) module monitors the sensor input for a temperature increase and checks that it is between the minimum and maximum working temperatures. If a temperature sensor input is at the high end of the working range, while the ambient air temperature and the engine temperature are within 10°C (18°F) of each other, the automatic temperature control (ATC) module disables front seat heating until the input decreases below the target temperature setting. The automatic temperature control (ATC) module interprets a temperature sensor input value of -45°C (-49°F) or below as an open circuit, and temperature sensor input value of 100°C (212°F) or more as a short circuit.