Windshield Base/Washer Spray Jet Heaters

E32 WINDSHIELD BASE/WASHER SPRAY JET HEATERS







E32 vehicles produced through the 1989 MY have a windshield base heater.

The lower portion of the windshield contains heating elements similar to those on the rear window. When operating, they prevent the wiper blades from freezing to the glass.

The IHKA control module monitors the signal from the ambient temperature sensor and, when ambient temperature is lower than 41 °F (5 °C), it activates the windshield base heating portion of a dual function relay. When ambient temperature exceeds 46 °F (8 °C), the windshield base heater is switched off.

All E32 vehicles have windshield washer spray jet heaters, but heater activation circuitry varies significantly during the range of E32 production. Up to 1992, the heaters are not related to the IHKA system.

The heaters are built into the washer spray jets, and are designed to prevent ice from obstructing the jets.







- On 1988 E32 vehicles, the washer jet heaters receive power as soon as the ignition is switched on, and they remain on until the ignition is switched off.
- 1989 - 1991 operation is similar, but the vehicle charging system must be functioning properly for the washer jet heaters to receive power (KI.61 relay).
- Beginning in 1992, the heaters became part of the IHKA system. They receive power through the windshield base heater/coolant pump relay when it is energized by the IHKA control module. Although 1992 vehicles are not equipped with a windshield heater, the spray jet heaters are powered when windshield base heater conditions exist (ON when ambient temperature is below 41 °F (5 °C); OFF when ambient temperature exceeds 46 °F (8 °C).
- For 1993 and 1994, operation is similar. The difference is that the jets are heated when either windshield heating or auxiliary coolant pump operation conditions exist.