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System Description
 
 
SYSTEM DIAGRAM
ComponentFunction
A/C amp.A/C Amp.
BCMBCM receives each signals, and controls PTC heater relay.
Combination meterCombination meter transmits ambient temperature signal to A/C amp. via CAN communication line.
ECM
  • ECM transmits engine speed signal and engine coolant temperature signal to A/C amp. via CAN communication line.
  • ECM transmits electrical power cut freeze signal to BCM via CAN communication line.
  • ECM receives idle up request signal to A/C amp. via CAN communication line.
Ambient sensorAmbient Sensor
PTC heaterPTC Heater
PTC heater relay 1/2/3PTC Heater Relay
 
 
INPUT/OUTPUT SIGNAL
Control unitSignal status
A/C amp.
  • Transmits the PTC thermal request signal to BCM via CAN communication.
  • Transmits the idle up request signal to ECM via CAN communication.
Combination meterTransmits the ambient temperature signal to A/C amp. via CAN communication.
ECM
  • Transmits the following signal to A/C amp. via CAN communication.
    • Engine speed signal
    • Engine coolant temperature signal
  • Transmits the electrical power cut freeze signal to BCM via CAN communication.
 
 
DESCRIPTION
  • BCM performs PTC heater relay ON/OFF control based on engine speed, engine coolant temperature, ambient temperature, electrical power cut freeze signal (permission signal, retention signal, stop signal), PTC thermal request signal, battery voltage, and electrical load state (high beam request, low beam request, and others).
  • When PTC heater relay turns ON, power supply is supplied to PTC heater. Heating element is heated and air flow temperature is increased. Heating is available for a period of time until engine coolant temperature is increased when engine starts cold in cold climate.
  • Idle up request signal is transmitted from A/C amp. to ECM while PTC heater operates. Idle speed is increased, warming-up is facilitated, and battery electric power is obtained.
  • Electric power supplied to PTC heating element is subject to PTC heater relay control conditions.
    PTC heaterOperationPTC heater relay 1PTC heater relay 2PTC heater relay 3
    OFFOFFOFFOFFOFF
    PTC heater-1LOWONOFFOFF
    PTC heater-2MIDONONOFF
    PTC heater-3HIONONON
notePTC heater operation depends on ambient temperature and battery voltage. PTC heater is ON when ambient temperature is 8°C (46.4°F) or less. PTC heater is OFF when ambient temperature is 12°C (53.6°F) or more. The operating voltage of the PTC heater ON/OFF changes depending on the electrical load of the vehicle or battery voltage.