PCM is activated by power supply. Signals from several sensors, such as CKPS and APS, is inputted to PCM. Comparing inputted siganals with control LOGIC saved at micro controller and EEPROM, PCM controlls engine as actuating injectors, solenoids and relays.
To guarantee accurate control, PCM performs SELF TEST, DIAGNOSIS of several sensors and actuators. And if serious trouble which affects vehicle performance occurrs, PCM sets DTCs.
At certain cases, PCM shuts down whole systems in order to prevent dangerous situation due to incorrect control.
P0642 is set when the voltage below 4240mV - minimum voltage of sensor power supply A generates from PCM - is detected for more than 3sec. This code is due to the short to ground in sensor power circuit or the voltage problem inside of PCM.
Item
Detecting Condition
Possible cause
DTC Strategy
Signal check, low
sensor power supply A circuit
PCM component
Enable Conditions
B+ : 11V ~ 16V
Threshold value
5V-voltage < 4.24V
Diagnosis Time
3 sec
MIL On Condition
NO MIL