Component Location
General Description
ECM is activated by power supply. Signals from several sensors, such as CKPS and APS, is inputted to ECM. Comparing inputted siganals with control LOGIC saved at micro controller and EEPROM, ECM controlls engine as actuating injectors, solenoids and relays.
To guarantee accurate control, ECM performs SELF TEST, DIAGNOSIS of several sensors and actuators. And if serious trouble which affects vehicle performance occurrs, ECM sets DTCs.
At certain cases, ECM shuts down whole systems in order to prevent dangerous situation due to incorrect control.
DTC Description
P0642 is set when the voltage below 4700mV - minimum voltage of sensor power supply 1 generates from ECM - is detected for more than 0.1 sec. This code is due to the short to ground in sensor power circuit or the voltage problem inside of ECM.
DTC Detecting Condition
Item | Detecting Condition | Possible Cause |
DTC Strategy | ? Voltage monitoring(Voltage below lower limit) | ? APS 1 power supply circuit ? ECM component |
Enable Conditions | ? IG KEY "ON" with pressing accellerator pedal |
Threshold Value | ? When the voltage is below the minimum voltage of sensor power supply. (below 4700mV) |
Diagnostic Time | ? 100ms |
Fail Safe | Fuel Cut | NO | |
EGR Off | NO |
Fuel Limit | YES |
Check Lamp | NO |
Specification
Sensor power 1 | Sensor power 2 |
APS1 4700mV~5100mV | RPS, APS 2, BPS 4830mV~5158mV |
Schematic Diagram
Signal Waveform
Fig.1) APS 1 supply is measured simultaneously , check if this waveform is within the specification (4.7~5.1V ) when turning ignition "ON".