The features of the Rear Defog Subsystem are: calculating the rear defog state, and modulation of the relay rear defog relay.
The rear defog operation can be modified due to load management of the vehicle electrical system.
1.5.2.1 REAR DEFOG RELAY MGMT BHVR (Statechart)
If a load management condition exists (load_shed = 1,2,3) and the rear defog state is true, the output to the relay shall be modified. If load_shed is equal to 1 or 2, the rear defog output shall be modulated at a frequency and duty cycle per calibratable parameters.
Transition Note [LOAD_SHED_IN==LM_
LEVEL0]/DEFOG_DRIVE_SIG=true [LOAD_SHED_IN!=LM_
LEVEL0]/DEFOG_DRIVE_SIG=false; /ON_TIME=(K_DUTY_CYCLE
*K_PERIOD)/100;OFF_TIME=((100-K_DUTY_CYCLE)*K_PERIOD)/100; REAR_DEFOG_RELAY_DISABLED RD_RELAY_
CONSTANT_ON [LOAD_SHED_IN!=LM_
LEVEL0]/DEFOG_DRIVE_SIG=false; RD_RELAY_
MODULATE [LOAD_SHED_IN==LM_
LEVEL0]/DEFOG_DRIVE_SIG=true; tm(en(RD_RELAY_OFF),OFF_TIME)/DEFOG_DRIVE_SIG=true; dly(ON_TIME)/DEFOG_DRIVE_SIG=false; REAR_DEFOG_
RELAY_DISABLED REAR_DEFOG_RELAY_
ENABLED [RDEFOG_ON_STATUS==
true] REAR_DEFOG_
RELAY_ENABLED REAR_DEFOG_RELAY_
DISABLED [RDEFOG_ON_STATUS==
false]/DEFOG_DRIVE_SIG=false;The operator request changes in the rear defog state by setting the rdefog_switch_status (pushing the rear defog switch). Once the rear defog has been activated, it shall automatically time out and turn itself off without any customer interaction. The timing function is modified by the customer interactions as well as vehicle speed and calibratable timer values.
1.5.3.1 CALC REAR DEFOG STATE BHVR (Statechart)
The rear defog state is changed when the user sets the rdefog_switch_status. Rdefog_lite follows the value of the rear defog state (the indicator is illuminated when the rear defog state is true. Timing of the rear defog shall only occur of the rear defog state is true. If vehicle speed > speed1 the timing function shall be suspended until vehicle speed drops below speed1. If the rdefog_switch_status is set while the rear defog state is true, the rear defog state will be set to false. After either the rd_timer=0 or rdefog_switch_status is set, the rdefog_lite status will change to false and the rd_timer will be set to rtimer2. If load shed = 3, then the rear defog state is set false.
Transition Note CALC_REAR_
DEFOG_DISABLED CALC_REAR_DEFOG_
ENABLED CALC_REAR_
DEFOG_ENABLED CALC_REAR_
DEFOG_DISABLED CALC_REAR_DEFOG_
DISABLED RDEFOG_LED=false;
RDEFOG_ON_STATUS=false;RD_TIMER=K_RTIMER1; REAR_DEFOG_NOT_TIMED [VEHICLE_SPEED_IN>K_
SPEED1] [VEHICLE_SPEED_IN<=K_
SPEED1] REAR_DEFOG_NOT_
TIMED REAR_DEFOG_
TIMED [VEHICLE_SPEED_IN<=K_
SPEED1] REAR_DEFOG_
TIMED CALC_REAR_DEFOG_
DISABLED tm(en(REAR_DEFOG_TIMED),RD_TIMER)/RDEFOG_LED=false;
RDEFOG_ON_STATUS=false;RD_TIMER=K_RTIMER2; REAR_DEFOG_
TIMED REAR_DEFOG_NOT_
TIMED [VEHICLE_SPEED_IN>K_
SPEED1]/RD_TIMER=K_RTIMER2;