Audi 4E Windshield Defroster Test Instructions (Solution)

Step 1:
Please verify that the following power-on prerequisites have been met.
The operating time of the windshield heating is determined by the climate control unit.
The relationship between heating duration and outdoor temperature follows a linear pattern between the two specified values.
At an ambient temperature of -20°C, the...
Heating time: approximately 5 minutes, and approximately 3 minutes at an ambient temperature of 0°C.
The heating duration applies to both the automatic and defrost settings.
If the activation conditions are met, but there are still malfunctions or poor performance, the windshield resistor should be checked.

Set the climate control to "automatic" mode.
- Switching threshold at an outlet temperature of < +35°C.
and an ambient temperature of less than +5°C.
- Engine running.
- No ECON operation.


Set the climate control to "Defrost."
- Activation threshold at an ambient temperature of <5> Set pin 2 to "1" -> Windshield heating enabled.
The FSH (Follicle-Stimulating Hormone) treatment will be discontinued if any of the following conditions are met:
- A shutdown request has been received from the BEM (dynamic energy management system).
- Shut-off due to climate control unit (one of the activation conditions is no longer met).
- ECON system is active.
- Climate control unit is switched off ("off").
- Deactivation in case of missing LIN bus communication (In the event of an error, the FSH will be deactivated by the climate control unit if "no communication" is detected. If communication is subsequently restored, the specified activation conditions will apply again.)
- Internal shutdown of the FSH control unit due to overheating, insulation fault, overvoltage or undervoltage, windshield crack, or internal short circuit.
ECU malfunction.

Measurement blocks:

45, 1: Power in Watts; 2: Power in Watts; Current in Amperes.

46, 1: Minimum disc resistance; 2: Maximum disc resistance; 3: Current disc resistance.

47, 1: Hardware status - Blower; 2: Software status - Blower; 3: Hardware status - FSH; 4: Software status - FSH.


Values:

With a test current of 50mA, the target value is a maximum of 2.4 ohms (see also measurement block 46).
The difference between the target power and the actual power consumption should not exceed 70-80 watts.