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

● CMPS power supply circuit

● APS 1 power supply circuit

● ECM component

Enable Conditions

● IG KEY "ON"

Threshold Value

● When the voltage is below the minimum voltage of sensor power supply.( below 4700mV )

Diagnostic Time

● 0.1 sec.

Fail Safe

Fuel Cut

NO

● Limp home mode is activated (Engine speed is fixed at 1200RPM )

EGR Off

NO

Fuel Limit

YES

MIL

OFF

Specification

Sensor power 1

Sensor power 2

Sensor power 3

APS1, CMPS

RPS, APS 2, BPS, MAFS

APT, VSCA, DPS, ECTS

4830mV~5158mV

4830mV~5158mV

4830mV~5158mV

Schematic Diagram
note
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Signal Waveform
note

※ Reference voltage from CMPS will be reading approximately 0.2V according to the position of Cam shaft.

Therefore, check the CMPS after disconnecting CMPS connector.

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