Seat Heaters System Description
Heater Control
Front Seat Heaters
The front seat heater control unit or the ventilated seat control unit sets the seat heater to High/Mid/Low or OFF based on the seat heater switch signals sent from the climate control unit via the B-CAN. The front seat heater control unit or the ventilated seat control unit monitors the thermistor resistance, the voltage/current/temperature to the heater, and the presence of communication with the climate control unit. When a certain period of time has elapsed after the thermistor value reaches the threshold value, the front seat heater control unit or the ventilated seat control unit automatically lowers the set temperature to one level lower.
Second Row Seat Heaters (With Second Row Seat Heater)
The second row seat heater control unit sets the seat heater to High/Mid/Low or OFF based on the seat heater switch signals sent from the climate control unit via the B-CAN. When a certain period of time has elapsed after the thermistor value reaches the threshold value, the second row seat heater control unit automatically lowers the set temperature to one level lower.
Remote Engine Start Cooperation Control
The remote engine start cooperation control works as follows. If outside temperature is low while the remote engine start system is used, the climate control unit sends the operation signal to the front seat heater control unit or the ventilated seat control unit to activate the front seat heater via the B-CAN. While the remote engine start is operating, the auto switch function performs. Also, during this control, each switch indicator turns on, and each switch operation becomes invalid.
Auto Switch Function
The auto switch function is an automatic control for the seat heater. Based on ventilation temperature, outside air temperature, and in-car temperature, the climate control unit sends request signals to the front seat heater control unit or the ventilated seat control unit via the B-CAN to control the seat heater operation.
Thermistor and Breaker
The seat cushion heater has a thermistor and breaker. The thermistor and breaker protects the seat heater circuit from overheating. The value of the thermistor is inputted to the control unit.
Front
Second Row
Failsafe Function
Thermistor Circuit Open Failure
Thermistor circuit open refers to a condition in which the value of the thermistor built in the seat cushion heater continues to be higher than the threshold value for a few seconds. When the control unit detects a shift from normal operation to this condition, it stops the seat heater operation and turns off the seat heater switch indicators.
Thermistor Circuit Short Failure
Thermistor circuit short refers to a condition in which the value of the thermistor built in the seat cushion heater continues to be lower than the threshold value for a few seconds. When the control unit detects a shift from normal operation to this condition, it stops the seat heater operation and turns off the seat heater switch indicators.
Heater Circuit Current Error
When the control unit detects an abnormal current value in the heater circuit, it stops the heater output immediately after detection and turns off the seat heater switch indicators.