Seat Heating, Basic Function - GF91.30-P-9900A
MODEL ALL (CAR) with CODE 401 (Climatised front seats)
MODEL ALL (CAR) with CODE 873 (Seat heaters for driver and front passenger)
MODEL ALL (CAR) with CODE 902 (Seat heater Plus for driver and front passenger)
Overview:
This document contains information on:
- General
- Function requirements
- Seat heating control, function
- Manual switch-on and switch-off, function
- Reduced heating output with multiple activation, function.
- Reduced seat heating in ECO drive program, function.
- Seat heating Plus (with code 902 (Seat heating Plus for driver and front passenger)), additional functions
- Actuation by other systems, function
General
The seat heating has the task of increasing the temperature of the seat cushion and/or seat backrest. The seat heating creates a more pleasant climate for vehicle occupants at low temperatures. The seat heating is performed via integrated heating elements in the seats.
Function requirements
- Circuit 15 or circuit 15R ON
- Only for front passenger seat heating:
Front passenger seat belt buckle contact (for approx. 15 minutes after change of circuit)
Seat heating control, function
Depending on the equipment installed, one of the following control units actuates the seat heating:
Overview of front seats seat heating control
| Installed control units/position of seat heating | Driver's seat heating | Front passenger seat heating |
| Without seat heating Plus | ||
| Without driver's seat control unit Without front passenger seat control unit | Seat climate control control unit | Seat climate control control unit |
| With driver's seat control unit Without front passenger seat control unit | Driver's seat control unit | Driver's seat control unit |
| With driver's seat control unit With front passenger seat control unit | Driver's seat control unit | Front passenger seat control unit |
| With seat heating Plus | Driver's seat heating control unit (sitting surface and seat backrest center part) Driver's seat control unit (seat side bolsters) |
Front passenger seat heating control unit (sitting surface and seat backrest center part) Front passenger seat control unit (seat side bolsters) |
Manual switch-on and switch-off, function
The seat climate control switch group in the doors of the respective side of the vehicle records the operation signals over the seat heating button and transmits these to the control system.
The heating output can set to 3 different levels. The actuation of the heating elements is performed by means of pulse width modulation (PWM) and thus enables actuation in 3 intensity levels (100 %/65 %/35 % power).
The control system sends the stage setting of the seat heating back to the seat climate control switch group. This actuates the LEDs in the seat heating button accordingly.
The heating output of the individual stages is also adjusted depending on the outside temperature. The heating output settings of the respective heating levels can be adjusted via the diagnostic tester.
Reduced heating output with multiple activation, function
If the seat heating is selected again with the same circuit status, the seat heating actuates heating level 3 at only 90 % of the heating output.
Reduced seat heating in ECO drive program, function
If the ECO drive program is activated, the seat heating switches to a mode to reduce the operating current. This is done by means of reduced pulse-width modulated signals. The control system multiplies the individual output levels of the pulse width modulated signals by an ECO factor and thus reduces the heating output.
If the ECO drive program is deactivated, the seat heating automatically returns to the normal mode. On vehicles with seat heating Plus, this continues to regulate to the specified temperature, but with reduced PWM values at the output of the actuating control unit.
It is possible to adjust the ECO factors using the diagnostic tester.
Seat heating Plus (with code 902 (Seat heating Plus for driver and front passenger)), additional functions
Additional temperature sensors are installed in the seat heating mats. To monitor the seat heating, the seat heating control unit reads in the signals from the corresponding heater pad temperature sensors directly and evaluates them. In line with this data and the set heating level, the seat heating Plus actuates the heater pads.
In addition, actuation is carried out depending on the vehicle interior temperature. This enables faster heating to be achieved. The lower the vehicle interior temperature, the faster the seat heating Plus heats up the heater pads.
Actuation by other systems, function
For actuation by other systems, the function requirement for circuit 15 or 15R ON does not apply. With circuit 30t, the other systems can also activate the seat heating.
The seat heating can also be actuated by the following systems:
- Pre-air conditioning
- Revitalization
- Massage programs of multicontour seats
| Further basic functions | |||
| Seat climate control timer-controlled shutoff, basic function | GF91.30-P-1000A | ||
| Seat climate control automatic shutoff, basic function | GF91.30-P-1001A | ||
| Control units | |||
| Seat control unit, basic function | Model 177 with code 241 (Memory switch for electrically adjustable left front passenger seat), with code 242 (Electrically adjustable front passenger seat with memory function) or with code 275 (Electrically adjustable driver's seat with memory function) | GF91.29-P-9890A | |
| Seat heater control unit, basic function | Vehicles with code 902 (Seat heater Plus for driver and front passenger) | GF91.30-P-9890A | |
| Seat climate control unit, basic function | Model 177 with code 401 (Climatised front seats) except code 275 (Driver's seat, electrically adjustable with memory function) Model 177 with code 873 (Seat heaters for driver and front passenger) except code 275 (Driver's seat, electrically adjustable with memory function) |
GF91.30-P-9891A |