System Diagram

Electrically Heated Front Seat Diagrams:

Electrically Heated Front Seat Components:

Locations of components

16 Instrument lighting rheostat
On the left-hand side of the facia

22A Fuse board
Behind the access panel in the glove compartment

57 Three-pole connector (1987)
Under the right-hand front seat

64 Heating pad
In the seat and backrest of the driver and co-driver's seats

65 Earthing point
Under the back seat

121 Seat switch for the heating pad (1987)
In the co-driver's seat

122 Eight-pole connector
One under the driver's seat
One under the co-driver's seat

231 Distribution terminal +54
In the electrical distribution box behind the glove compartment

252 Rheostat for the heating pad, driver's seat
On the facia

253 Rheostat for the heating pad, co-driver's seat
On the facia

254 Thermostat for the heating pad, driver's seat
In the driver's seat

255 Thermostat for the heating pad, co-driver's seat
In the co-driver's seat

341 Earthing point
On the left-hand front seat member

Operation
Both front seats of the car are electrically heated. The heating is controlled by rheostats.

Heating pads 64 are supplied from fuse 10 and are switched on and off by thermostats 254 (in the driver's seat) and 255 (in the co-driver's seat). The thermostats consist of an NTC (Negative Temperature Coefficient) resistor, whose resistance varies with the temperature of the heating pad.

The temperature of the heating pad of the driver's seat can be set by means of rheostats 252 and 253, which have four positions: 0-1-2-3. The heating is switched off in position 0, while at position 3 it delivers maximum heat. When the heating pad has reached the predetermined temperature for the selected position, the supply to the heating pad will be interrupted. When the temperature has dropped to the lower limit for the selected rheostat position, the heating pad will again be energized.

1987 model
The supply to the heating pad of the co-driver's seat is wired across seat switch 121. When a load is applied to the seat, the seat switch will close and the heating pad can be switched on and off by thermostat 255. So this heating pad will be operative only when a person is seated in the co-driver's seat.

The lamps in the rheostats are supplied from instrument lighting rheostat 16.

Fault-tracing hints

1. Turn the ignition switch to the drive position.
2. Check fuse 10 and check that the supply to rheostats 252 and 253 is live.
3. Check that thermostats 254 and 255 are intact. (Measure between pins 1 and 5 of connector 122.)
4. Check seat switch 121 in the co-driver's seat (1987).
5. Measure the resistance of the heating elements in the heating pads, to check for open-circuits.
6. Check the connectors, wiring and earth connections.