The Electronic Throttle Control(ETC) system is made of the components throttle body, Throttle Position Sensor(TPS) 1&2 and Accelerator Position Sensor(APS) 1&2. The APS is mounted in the accelerator pedal to detect the opening angle of the accelerator pedal. It has 2 sensors to detect the accelerator position and a malfunction of the accelerator position sensor. The PCM judges the current opening angle of the accelerator pedal from APS1&2, and the PCM controls the throttle motor based on these signals.
Checking output signals from APS 1 and 2 under detecting condition, if output signals difference between APS 1 and 2 are detected more than 4.5% for the specified number of times., PCM sets P2138. And then MIL(Malfunction Indication Lamp) turns on.
Item
Detecting Condition
Possible Cause
DTC Strategy
? This code detects a correlation error between APS 1 and APS 2
? Poor connection
? Open or short in APS Circuit
? Faulty APS
? Faulty PCM
Enable Conditions
? Ignition "ON"
Threshold value
? Difference between APS1 and APS2 Normalized values > 4.5%
Diagnosis Time
? Contineous
MIL On Condition
? 1 Driving Cycle
Pedal Position
Output Voltage(V) [Vref = 5.0V]
APS1
APS2
C.T
0.7 ~ 0.8V
0.275 ~ 0.475V
W.O.T
3.8 ~ 4.4V
1.75 ~ 2.35V
Fig.1) This is a signal waveform of APS 1 & 2 which shows that APS 2 increases voltage just half of APS 1 voltage increase when accelleration.