Heated Windshield, Function - GF67.10-P-0002LF
Model 217.3
with code 597 (Heated windshield)
Model 222
up to model year 2018
with code 597 (Heated windshield)
Function requirements, general
- No undervoltage or overvoltage
- Circuit 15 On or pre-entry climate control, function active (Model 222.004/057/104/157/163) or engine running or drivetrain operational
The electronic ignition lock control unit sends the status of circuit 15 via interior CAN to the climate control, control unit.
The "engine running" or "drivetrain operational" signal is sent by the CDI control unit or ME-SFI [ME] control unit via the drive train CAN, powertrain control unit, chassis FlexRay, electronic ignition lock control unit and interior CAN to the climate control, control unit.
Heated windshield
The windshield can be heated for the purpose of de-icing and preventing fogging. The climate control unit controls and monitors the heated windshield function.
The heated windshield function is triggered by:
- activation of the defrosting function
- activation of the pre-entry climate control function (Model 222.004/057/104/157/163)
- If fogged windows are impending
The climate control unit calculates the specified heat output value and sends this to the windshield heater control unit via climate control LIN 2. The windshield heater control unit responds by actuating the heated windshield. The heated windshield is operated at a voltage of 42 V, which is transformed by the windshield heater control unit. The windshield heater control unit monitors the function of the heated windshield and sends appropriate basic data such as power consumption, temperature or short circuit of the heated windshield to the climate control unit via climate control LIN 2.
The climate control unit evaluates the following variables for controlling the function:
- Status of defrosting function
The defrosting function is started by activation of the defrosting button on the climate control operating unit. The climate control operating unit reads in the status of the defrosting button directly and sends the status to the climate control, control unit via the climate control LIN. When the defrosting button is pressed and the outside temperature is below 10°C, the climate control unit starts the heated windshield function. When the defrosting button is pressed again, the climate control unit ends the function.
- Outside temperature
The outside temperature is recorded by the outside temperature sensor. The front SAM control unit directly reads in the outside temperature sensor signals, calculates the outside temperature and sends the data to the climate control, control unit via interior CAN. At outside temperatures below 5°C and an active defrosting function, the climate control unit starts the heated windshield function.
- Status of the pre-entry climate control function (Model 222.004/057/104/157/163)
Pre-entry climate control is controlled by the climate control unit. If pre-entry climate control is active in the heating operating mode and if the outside temperature is below 10°C, the climate control unit starts the heated windshield function.
- Fogging tendency (fogging index)
The fogging index describes the windshield's tendency to fog up inside. The fogging index is calculated by means of the dew point temperature.
A humidity and temperature sensor is integrated in the rain/light sensor with additional functions. This sensor measures the relative air humidity and surface temperature directly at the inside of the windshield. These values are used by the rain/light sensor with additional functions to calculate the dew point temperature. The comparison of the surface temperature with the dew point temperature enables any (impending) fogging of the windshield to be detected. The rain/light sensor with additional functions sends the surface temperature on the inside of the windshield and the dew point temperature via the rain/light sensor LIN, front SAM control unit and interior CAN to the climate control, control unit. If fogging is impending, the climate control unit starts the heated windshield function.
- "Engine running" or "drivetrain operational" status
Operation of the heated windshield is comparably intensive in terms of energy. To ensure onboard electrical network stability is not endangered by operation of the heated windshield, the climate control unit evaluates the stability of the engine running or, if the engine is switched off, the "drivetrain operational" signal. The "engine running" or "drivetrain operational" signal is sent by the CDI control unit or ME-SFI [ME] control unit via the drive train CAN, powertrain control unit, chassis FlexRay, electronic ignition lock control unit and interior CAN to the climate control, control unit.
Automatic switch off
The heated windshield is switched off automatically after 8 min or at an outside temperature of greater than 10°C.
| Electrical function schematic for heated windshield | PE67.10-P-2051-97SEA | ||
| Overview of system components for climate control | GF83.40-P-9994LF |