The ECM provides a 5volt reference voltage to the Acceleration Position Sensor2(APS2), A/C pressure sensor and power steering sensor. The ECM monitors reference voltage deviation from the power supply circuit of the sensors
ECM sets DTC P0643 if the ECM detects reference voltage higher than threshold value
Item
Detecting Condition
Possible Cause
DTC Strategy
? Electrical Check
? Open or short to battery in power circuit
? Poor connection or damaged harness
? Faulty ECM
Enable Conditions
? Ignition "ON"
Threshold Value
? APS2 voltage > 5.5V
Diagnostic Time
? 0.1sec.
Limp-Home
? Forced limited power mode : The ECM limits opening angle of the throttle valve to max. 50% and engine torque to a certain pre-determined value.
? After idle recognition, the ECM uses APS1 signal to calculate the current opening angle of the throttle valve.