Rear Window Heater, Function - GF67.29-P-3002KJ
MODEL 453.0/3/4
Shown on model 453 (except 453.091/391/491) with code (I77) Manual air conditioning system
Shown with code I01 (Automatic air conditioning) or model 453.091/391/491
Function requirements, general
- Engine speed signal (except model 453.091/391/491) (Signal from ME-SFI control unit)
- Drivetrain iperational (mode "READY" (only model 453.091/391/491)) (Signal from electric drive control unit)
Rear window heater, general
If the rear window heater is active, the heated outside mirror is always active as well.
The rear window heater function comprises the following partial functions:
- Function sequence for manual switch-on/off (model 453 except 453.091/391/491 without code I01 (Automatic air conditioning))
- Function sequence for manual switch-on/off (model 453 with code I01 (Automatic air conditioning) and model 453.091/391/491)
- Fuction sequence for automatic switch-on during defrost mode (vehicles with code I01 (Automatic air conditioning) and model 453.091/391/491)
- Function sequence for determining switch-on duration
- Function sequence for switching off soft top opening (model 453.4)
Function sequence for manual switch-on/off (model 453 except 453.091/391/491 without code I01 (Automatic air conditioning))
On vehicles with code I77 (Manual air conditioning) or code I78 (Heating system), the rear window heater is switched on and off via the rear window heater button in the climate control and operating unit. The rear window heater button in the air conditioning control and operating unit is read in directly via direct line by the center SAM control unit. The center SAM control unit directly actuates the rear window heater via the heated rear window/outside mirror relay. The center SAM control unit directly actuates the LED in the rear window heater button to confirm the function.
The rear window heater function is terminated when the rear window heater button is pressed again. The LED goes out simultaneously.
Function sequence for manual switch-on/off (model 453 with code I01 (Automatic air conditioning) and model 453.091/391/491)
The rear window heater is switched on and off with the rear window heater button in the automatic air conditioning control and operating unit. The air conditioning control unit directly reads in the status of the rear window heater button and relays it to the air conditioning control unit via the climate control LIN. Then the air conditioning control unit transmits the request "Rear window heater on" to the center SAM control unit via the interior CAN. The center SAM control unit then directly actuates (except model 453.091/391/491) or operational drivetrain (only model 453.091/391/491) the rear window heater via the heated rear window/outside mirror relay (together with the mirror heater) when the engine is running. The climate control and operating unit directly actuates the LED in the rear window heater button to confirm the function.
The rear window heater function is terminated when the rear window heater button is pressed again. The LED goes out simultaneously.
On model 453.091/391/491 with code 535 (smart Media System) and with code I01 (Automatic air conditioning) the symbol for the heater and the symbol for the air conditioning as well as the current energy flow are indicated in the touch screen (A40/3p1) of the Smart Radio Multimedia Navigator (A40/3) in the menu "Vehicle" under "electric Drive" and "Energy flow", when the rear window heater or the defrost function is activated. For this purpose the climate control unit transmits the status and the electric drive control unit the corresponding information over the interior CAN to the Audio-Gateway control unit (N93/1), which transmits this information via telematic CAN to the smart Radio Multimedia Navigator.
On model 453.091/391/491 with code 535 (smart Media System) and with code I01 (Automatic air conditioning) the symbol for the heater and the symbol for the air conditioning as well as the current energy flow are indicated in the touch screen (A40/3p1) of the Smart Radio Multimedia Navigator (A40/3) in the menu "Vehicle" under "electric Drive" and "Energy flow", when the rear window heater or the defrost function is activated. For this purpose the climate control unit transmits the status and the electric drive control unit the corresponding information over the interior CAN to the Audio-Gateway control unit (N93/1), which transmits this information via telematic CAN to the radio smart Radio Multimedia Navigator.
Fuction sequence for automatic switch-on during defrost mode (model 453 with code I01(Automatic air conditioning) and model 453.091/391/491)
When the defrosting mode is switched on to defrost or defog the windshield on with the defrost button (N20s4) on the climate control unit, the rear window heater is switched on together with the rearview mirror heater parallel to the defroster for the windshield to defrost or defog the rear window and exterior rearview mirrors. This defrosts and defogs the rear window and the outside mirror. For this purpose the status of the defrost button the climate control operating unit is read in directly and the request "Defrost" is transmitted to the climate control unit via the climate LIN. Then the air conditioning control unit transmits the request "Rear window heater on" to the center SAM control unit via the interior CAN. The center SAM control unit then directly actuates (except model 453.091/391/491) or operational drivetrain (only model 453.091/391/491) the rear window heater via the heated rear window/outside mirror relay (together with the mirror heater) when the engine is running. To confirm the status, the LED in the defrost button is actuated by the climate control operating unit.
For detailed information on the defrost mode of the automatic air conditioning see function description "Climate control, function".
Function sequence for determining switch-on duration
The information whether and how long the mirror heater is switched on, is stored in the center SAM control unit. On vehicles with code I01 (Automatic air conditioning) The outside temperature is considered additionally for activation and control of the outside mirror and rear window heater. The outside temperature is sensed by the outside temperature sensor in the right electrically adjustable and heated outside mirror. The instrument cluster directly reads in the signal of the outside temperature sensor, calculates the outside temperature and sends the calculated value to the climate control unit over the interior CAN.
- The normal duty cycle is t = 10 to 15 min.
- The minimum duty cycle is t = 2 min.
- The maximum duty cycle is t = 26 min.
At outside temperatures of T > 50°C, the duty cycle of the rear window and mirror heater is limited to t = 2 min to protect the rear window.
Function sequence for switching off soft top opening (model 453.4)
When the rear soft top is opened, the rear window heater switches off together with the mirror heater. For this purpose the soft top control unit transmits the status of the soft top to the center SAM control unit via the interior CAN. The center SAM control unit then deactivates the rear window heater together with the mirror heater. The mirror heater is not switched on as well when the rear soft top is opened, even when a request from the mirror heater via the rear window heater button is present.
| Function schematic for electrical rear window heater | Model 453.0 (except 453.091/391/491) without code I01 (Automatic air conditioning) | PE67.29-P-2051-97BBA | |
| Model 453 (except 453.091/391/491) with code I01 (Automatic air conditioning) | PE67.29-P-2051-97BBB | ||
| Model 453.091/391/491 | PE67.29-P-2051-97BEA | ||
| Overview of system components for climate control | Model 453 (except 453.091/391/491) | GF83.40-P-9994KJ | |
| Model 453.091/391/491 | GF83.40-P-9994KJE |