Seat Heating, Basic Function - GF91.30-P-9900A
Model All (4xWD, CAR)
Overview
This document contains information on:
- General
- Function requirements
- Function
- Front seat heater control
- Seat heating control in rear passenger compartment
- Manual switch-on/off (cars)
- Manual switch-on/off (off-road vehicles)
- Reduced heating output with multiple activation
- Reduced heating output in ECO drive program
- Additional seat heater functions, comfort
- Independent actuation of seat cushion and seat backrest heating
- Actuation by other systems
General
The seat heating has the task of increasing the temperature of the seat cushion 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.
Depending on the vehicle equipment and installed seat, the following surfaces can be heated:
- Seat cushion
- Leg rest
- Seat side bolsters, seat surface
- Seat backrest
- Seat side bolsters, seat backrest
- Head restraint
Function requirements
- Circuit 15 or circuit 15R or circuit 50 ON (or vehicle status "LIVING").
- Only for front passenger seat heating: No transition from front passenger seat occupied/front passenger seat belt buckle inserted to front passenger seat not occupied/seat belt buckle not inserted for more than 10 s.
In this case, the front passenger seat heating is automatically switched off. If an occupied front passenger seat or an inserted front passenger seat belt buckle is detected again within 3 minutes, the front passenger seat heating is automatically switched on again. After 3 minutes have elapsed, it must be switched on manually.
Function
Front seat heater control
Depending on equipment installed, different control units control the seat heating, see following table.
Overview of front seats seat heating control
| Installed control units/position of seat heating | Driver's seat heating | Front passenger seat heating |
|---|---|---|
| Without comfort seat heating | ||
| 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 seat control unit | Driver seat control unit |
| With driver's seat control unit With front passenger seat control unit |
Driver seat control unit | Front passenger seat control unit |
| With comfort seat heating | Driver seat heater control unit (seat surface and seat backrest center section) and driver seat control unit (seat side bolsters) or Driver seat control unit |
Front passenger seat heater control unit (seat surface and seat backrest center section) and front passenger seat control unit (seat side bolsters) or Front passenger seat control unit |
Seat heating control in rear passenger compartment
Control of the seat heater is dependent on the equipment installed:
- If the rear seat is equipped with a seat control unit, it controls the seat heating.
- On rear seats without the seat control unit, a seat heater control unit is installed.
- With comfort seat heating, the seat control unit is often supported by an additional seat heater control unit.
- When the head restraints in the rear passenger compartment are heated, the so-called cozy cushions are heated. The cozy cushion and head restraint are connected through the snap fasteners.
Manual switch-on/off (cars)
On cars, the seat climate control switch group is installed in the doors or at the side wall of the respective side of the vehicle. The seat climate control switch group records the control signals via the seat heater button and sends them to the control system. Depending on the model involved, operation through the multimedia system control is also possible, e.g. via the voice 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.
Depending on the equipment, it is also possible to operate the seat heating in the rear passenger compartment via the vehicle's own tablet PC or the rear touchscreen.
Manual switch-on/off (off-road vehicles)
The buttons for the seat heating are integrated into the central control panel in the instrument panel. The buttons for the seat heating detect the control signals and transmit these to the control system.
The heating output can be set to 2 different stages. The actuation of the heating elements is performed by means of pulse width modulation (PWM) and thus enables actuation in 2 intensity stages.
The control system sends the stage setting of the seat heating back to the central control panel. This actuates the LEDs in the buttons for the seat heating 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
If the seat heating is selected again with the same circuit status, the seat heating actuates heating level 3 with only 90% of the heating output.
Reduced heating output in ECO drive program
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.
Additional seat heater functions, comfort
Additional temperature sensors are installed in the seat heating mats. To monitor the seat heating, the seat heating control reads in the signals from the corresponding heater pad temperature sensors directly and evaluates them. The comfort seat heating actuates the heater pads to match this data and the set heating level.
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 comfort seat heating heats up the heater pads.
Independent actuation of seat cushion and seat backrest heating
Depending on equipment installed, the heating of the seat cushion and seat backrest can be adjusted independently of each other using the multimedia system control.
Actuation by other systems
For actuation by other systems, the function requirement for circuit 15, 15R or 50 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
| Function schematics | |||
| Function schematic for actuating front seat heating | Model 118, 177, 243, 247 with code 401 (Climatised front seats) Model 118, 177, 243, 247 with code 873 (Left and right driver's seat heating) | PE91.30-P-2502-97A | |
| Model 167 with code 401 (Climatised front seats) except code 902 (Front comfort seat heating) Model 167 with code 873 (Left and right driver's seat heating) except code 902 (Front comfort seat heating) | PE91.30-P-2502-97B | ||
| Model 167 with code 902 (Front comfort seat heating) except code 401 (Climatised front seats) except code 873 (Left and right driver's seat heating) | PE91.30-P-2502-97C | ||
| Model 206, 214, 236, 254 with code 873 (Left and right driver's seat heating) | PE91.30-P-2502-97H | ||
| Model 213, 238, 257, 290 with code 873 (Left and right driver's seat heating) | PE91.30-P-2502-97E | ||
| Model 213, 238, 257, 290 with code 902 (Front comfort seat heating) | PE91.30-P-2502-97F | ||
| Model 223 with code 873 (Left and right driver's seat heating) Model 223 with code 902 (Front comfort seat heating) | PE91.30-P-2502-97G | ||
| Model 192, 232 with code 873 (Left and right driver's seat heating) | PE91.30-P-2502-97J | ||
| Model 293 with code 401 (Climatised front seats) Model 293 with code 873 (Left and right driver's seat heating) | PE91.30-P-2502-97D | ||
| Model 294, 295, 296, 297 with code 401 (Front seat climate control); model 294, 295, 296, 297 with code 873 (Left and right driver's seat heating); model 294, 295, 296, 297 with code 902 (Front comfort seat heating) | PE91.30-P-2502-97I | ||
| Function schematic for actuating rear seat heating | Model 167 with code 872 (Left and right rear seat heating) except code 886 (Seat heater for 3rd seat row) | PE91.30-P-2503-97A | |
| Model 167 with code 886 (Seat heater for 3rd seat row) | PE91.30-P-2503-97B | ||
| Model 167 with code 903 (Rear comfort seat heating) except code 872 (Left and right rear seat heating) except code 886 (Seat heater for 3rd seat row) | PE91.30-P-2503-97H | ||
| Model 206, 214, 254 with code 872 (Left and right rear seat heating) | PE91.30-P-2503-97G | ||
| Model 213 as of model year 2021 with code 872 (Left and right rear seat heating) except code 223 (Electric backrest adjustment and head restraints) Model 238, 257, 290 as of model year 2021 with code 872 (Left and right rear seat heating) | PE91.30-P-2503-97D | ||
| Model 213 as of model year 2021 with code 223 (Electric backrest adjustment and head restraints) with code 872 (Left and right rear seat heating) Model 213 as of model year 2021 with code 223 (Electric backrest adjustment and head restraints) with code 903 (Rear comfort seat heating) | PE91.30-P-2503-97E | ||
| Model 223 with code 872 (Left and right rear seat heating) Model 223 with code 903 (Rear comfort seat heating) | PE91.30-P-2503-97F | ||
| Model 293 with code 872 (Left and right rear seat heating) | PE91.30-P-2503-97C | ||
| Model 294, 295, 296, 297 with code 872 (Left and right rear seat heating) Model 297 with code 402 (Rear seat climate control) Model 297 with code 903 (Rear comfort seat heating) | PE91.30-P-2503-97I | ||
| Model 296 with code 886 (Seat heater for 3rd seat row) except code 872 (Left and right rear seat heating) | PE91.30-P-2503-97J | ||
| Further basic functions | |||
| Seat climate control timer-controlled shutoff, basic function | Model all (CAR) with code 872 (Left and right rear seat heating) Model all (CAR) with code 873 (Left and right driver's seat heating) Model all (CAR) with code 886 (Seat heater for 3rd seat row) Model all (CAR) with code 902 (Front comfort seat heating) Model all (CAR) with code 903 (Rear comfort seat heating) |
GF91.30-P-1000A | |
| Seat climate control automatic shutoff, basic function | Model all (CAR) with code 872 (Left and right rear seat heating) Model all (CAR) with code 873 (Left and right driver's seat heating) Model all (CAR) with code 886 (Seat heater for 3rd seat row) Model all (CAR) with code 902 (Front comfort seat heating) Model all (CAR) with code 903 (Rear comfort seat heating) |
GF91.30-P-1001A | |
| Seat control unit, basic function | Vehicles with seat heating and electrical seat adjustment at front, vehicles with seat heating and electrical seat adjustment in rear passenger compartment | GF91.29-P-9890A | |
| Seat climate control unit, basic function | Vehicles with seat heating and without electrical seat adjustment as well as, where applicable, vehicles with code 902 (Seat heating Plus for driver and front passenger) and, where applicable, vehicles with code 903 (Seat heating Plus for rear outer seats) | GF91.30-P-9891A | |
| Tablet cradle electric controller unit, basic function | Vehicles with code 447 (MBUX rear passenger compartment tablet) | GF54.21-P-2007A | |
| Rear passenger compartment center console touchscreen, basic function | Model 290 as of model year 2021 with code 224 (Individual rear seats) with code 872 (Left and right rear seat heating) |
GF54.21-P-2009A | |
| Component descriptions | |||
| Seat heating heater pad/heat mat, component description | Model 223 | GF91.30-P-3211A | |
| Model 243 | GF91.30-P-3211B | ||
| Model 297 | GF91.30-P-3211D | ||
| Model 295 | GF91.30-P-3211E | ||
| Model 232 | GF91.30-P-3211F | ||
| Model 296 | GF91.30-P-3211G | ||
| Model 464 | GF91.30-P-3211J | ||
| Model 214 | GF91.30-P-3211K | ||
| Model 118 as of model year 2023 Model 177, 247 as of model year 2023 |
GF91.30-P-3211L | ||
| Model 167 as of model year 2023 |
GF91.30-P-3211M | ||
| Model 294 | GF91.30-P-3211N |