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Heated Glass Element: Description and Operation

Voltage is applied to the Rear Defogger and Heated Mirror grids through the Defogger Relay. With Ignition in "RUN," voltage is applied to one side of the Defogger Relay Coil. When the Rear Defogger "ON/OFF" Switch is activated, a ground signal is sent from the Heater/Vent/Air Conditioning (HVAC) Control Head (Manual A/C) or from the HVAC Programmer (Electronic A/C) to the Central Control Module (CCM). Upon receiving this ground signal, and only if the Engine is RUNNING, the CCM then energizes the Defogger Relay by grounding the other side of the Defogger Relay Coil. When energized, the normally open contacts in the Defogger Relay close, applying voltage to heat the Rear Defogger and Heated Mirror grids. The CCM will energize the Defogger Relay for 10 minutes during the first activation of the Rear Defogger and Heated Mirrors after Ignition "ON" - Engine RUNNING, and for 5 minutes each additional activation. This timing process will reset at each Ignition cycle.