HRW

HRW

When the engine is running and the HRW is selected on, the ATC (automatic temperature control) module illuminates the LED (light emitting diode) above the switch and energizes the HRW relay in the AJB (auxiliary junction box). After 10 minutes (when ambient temperature is -15 degrees C (5 degrees F) or above) or 17 minutes (when ambient temperature is less than -15 degrees C (5 degrees F)), the ATC (automatic temperature control) module extinguishes the LED (light emitting diode) and operates the HRW at low power for 60 minutes. During the 60 minutes, the ATC (automatic temperature control) module cycles the HRW relay off for 80 seconds and on for 40 seconds. If the HRW switch is pressed again during the low power phase, the ATC (automatic temperature control) module illuminates the LED (light emitting diode) again and returns the HRW to full power by keeping the HRW relay energized for 5 minutes. At the end of the 5 minutes the LED (light emitting diode) is extinguished and the 60 minutes low power phase is repeated.

The ATC (automatic temperature control) module outputs a K bus message when the HRW is active. The message allows the navigation computer to compensate for the effect of the magnetic field generated when the HRW is active. In addition, the GEM (generic electronic module) transfers the message onto the P bus for the door modules, which activate the door mirror heaters together with the HRW.