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 ECM judges the current opening angle of the accelerator pedal from APS1&2, and the ECM controls the throttle motor based on these signals.
ECM sets DTC P2128 if the ECM detects output voltage higher than the possible range of a properly operating APS2
Item
Detecting Condition
Possible Cause
DTC Strategy
? Electrical Check
? Open in ground circuit
? Short to battery in signal circuit
? Poor connection or damaged harness
? APS2
Enable Conditions
? No error for power supply circuit in APS2
Threshold Value
? APS2 > 2.5V
Diagnostic Time
? 0.3 sec.
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.
Test Condition
APS1
APS2
Closed Throttle Status
Approx. 0.58~0.93V
Approx. 0.29~0.36
Wide Open Throttle
Approx. 3.85~4.35V
Approx. 1.93~2.18V
Scan Tool Parameter
Scan Tool Screen
ACCEL PEDAL VOLT-1
ACCEL PEDAL VOLT-2
Normal value with ignition "ON" & engine "OFF"
APS 1&2 output voltage increases smoothly in proportion with the depressing acceleration pedal amount. The output voltage of the APS2 is half of the APS1
Fig. 1
Accelerator pedal released
Approx. 0.29~0.38
Fig. 2
Accelerator pedal fully depressed
Fig. 3
Abnormal value with ignition "ON" & engine "OFF"
APS1 power circuit open
Approx. 0.00V
-
APS1 ground circuit open or signal circuit short to battery
Approx. 4.91V
APS1 signal circuit open or short to ground
APS2 power circuit open
APS2 ground circuit open or signal circuit short to battery
Approx. 4.78V
Fig. 4
APS2 signal circuit open or short to ground