Operation

Heated Seats

OPERATION

General
Feed from the positive battery terminal (C0192) is supplied to fusible link 3 and fusible link 4 of the engine compartment fuse box (C0632) on an R wire. Fusible link 4 (C0574) is connected to the auxiliary relay (C0587) by an NW wire. The earth path for the relay coil is controlled by the Central Control Unit (CCU) (C0592),

Fusible link 3 (C0571) is connected to the ignition switch (C0028) by an N wire. When the ignition switch is turned to the 'ignition' position, current flows across the switch (C0028) to fuse 8 of the passenger compartment fuse box (C0588) on an OG wire. Fuse 8 provides an ignition feed to the CCU, which is mounted directly onto the rear of the passenger compartment fuse box.

When the CCU receives an ignition feed, it energizes the auxiliary relay by providing an earth path for the relay coil. The energized auxiliary relay provides a feed to fuse 29, which is also located in the passenger compartment fuse box.

Fuse 29 (C0584) provides a feed to the LH heated seat switch (C0249) and the RH heated seat switch (C0250) on N wires.

LH Seat
When the LH heated seat switch is pressed, current flows across the switch contacts (C0249) to the LH heated seat relay (C1221) on a US then R wire. Operation of the heated seat relay (C1221) is controlled by the temperature sensor on a G wire. The temperature sensor is a normally closed switch. Current flows across the switch to earth on a G then N then B wire.

When the temperature of the seat is within acceptable levels, the heated seat relay (C1221) provides a feed to the seat heater elements on an RW wire. The elements are wired in series and earthed on an N then B wire.

If the temperature sensor detects the temperature of the seat is too high, it cuts the earth path for the heated seat relay. This de-energizes the relay until seat heat temperature decreases to acceptable levels.

RH Seat
When the RH heated seat switch is pressed, current flows across the switch contacts (C0250) to the RH heated seat relay (C1221) on a UK then R wire. Operation of the heated seat relay (C1221) is controlled by the temperature sensor on a G wire. The temperature sensor is a normally closed switch. Current flows across the switch to earth on a G then N then B wire.

When the temperature of the seat is within acceptable levels, the heated seat relay (C1221) provides a feed to the seat heater elements on an RW wire. The elements are wired in series and earthed on an N then B wire.

If the temperature sensor detects the temperature of the seat is too high, it cuts the earth path for the heated seat relay. This de-energizes the relay until seat heat temperature decreases to acceptable levels.