Heated seats (HS) function - GF91.30-P-0003GZ: Notes

MODEL 164 with CODE (873) Heated left and right front seats with CODE (401) Front deluxe seats, incl. seat heating and seat ventilation with CODE (872) Electrically heated left and right rear seats

Fig 1: Identifying Heated Seats Function - Shown On Model 164.8

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Shown on model 164.8

Function requirements

Circuit 15R or circuit 15 "ON".

Actuation of seat heating elements

The heating elements in the front seats are actuated by the front SAM control unit.

For vehicles with code 872, the heating elements in the 2nd seat row are actuated by the HS [SIH], seat ventilation and steering wheel heater control unit.

Actuation is performed by way of a duty cycle, which is implemented as follows:

Stage 1= Low heat output with a duty cycle of approx. 0 to 40 %, here one LED is lit.
Stage 2= Medium heat output with a duty cycle of approx. 41 to 70 %, here two LEDs are lit.
Stage 3= High heat output with a duty cycle of approx. 71 to 100 %, here three LEDs are lit.

Time control

A timer control for the heated seats is located in the front SAM control unit and the HS [SIH], seat ventilation and steering wheel heater control unit:

Switch-on of stage 3 for t = 5 min
Switchover to stage 2 for t = 10 min
Switchover to stage 1 for t = 20 min
Heated seats shutoff

On vehicles with code 401, the heated seats remain active in stage 1 when seat ventilation is active.

The times of the three heating stages can be parameterized using STAR DIAGNOSIS in the front SAM control unit and the HS [SIH], seat ventilation and steering wheel heater control unit.

Front heated seats

With the integrated heated seats function, it is possible to heat the seat cushions and backrests in three heating stages. The left front HS [SIH] switch and the right front HS [SIH] switch are designed as buttons. They are located on the upper control panel control unit. The left front HS [SIH] switch and the right front HS [SIH] switch change the respective switching state ("ON" or "OFF") depending on the number of actuations. Each actuation is sent by the upper control panel control unit over the interior CAN to the front SAM control unit. The front SAM control unit in response actuates the respective heated cushion of the front seats. If the heated seats are switched on, the LED indicator lamps indicate the corresponding actuation on the upper control panel control unit.

Rear heated seat (with code 872)

With the integrated heated seats, it is possible to heat the seat cushions and backrests in the 2nd seat row in three heating stages. The left HS [SIH] switch, 2nd seat row and the right HS [SIH] switch, 2nd seat row are designed as buttons. They are located on the RCP [HBF] control unit. The left HS [SIH] switch, 2nd seat row and the right HS [SIH] switch, 2nd seat row change the respective switching state ("ON" or "OFF") depending on the number of actuations. Each actuation is sent by the RCP [HBF] control unit over the interior CAN to the HS [SIH], seat ventilation and steering wheel heater control unit. The HS [SIH], seat ventilation and steering wheel heater control unit actuates in response the respective heated cushions in the 2nd seat row. If the heated seats are switched on, the LED indicator lamps indicate the corresponding actuation on the RCP [HBF] control unit.

Heated seats (HS), networking of components	GF91.30-P-0003-01GZ
Heated seats (HS) block diagram	GF91.30-P-0003-03GZ
Switch heated seats on, off, over	GF91.30-P-5217GZ