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 throttle body contains the actuator, the throttle plate and the throttle position sensor (potentiometer), which are integrated in one housing. The actuator consists of a DC motor with a two-stage gear. The opening angle of the throttle valve is detected by the throttle position sensor which is mounted on the throttle body. And it provides feedback to the ECM to control the throttle motor in order to control the throttle valve opening angle properly in response to the driving condition.
Checking output signals from TPS under detecting condition, if the difference between real and target throttle position is above the specified value, ECM sets P0638.
Item | Detecting Condition | Possible cause | |
Case 1 | DTC Strategy |
•
Return spring check |
•
Throttle stuck
•
Open in motor circuit
•
Faulty motor
•
Faulty ECM |
Enable Conditions |
•
Ig On | ||
Threshold value |
•
Throttle positon > limp-home pos.+3% | ||
Diagnosis Time |
•
0.56 sec | ||
Case 2 | DTC Strategy |
•
Open spring check | |
Threshold value |
•
Throttle positon < limp-home pos.- 1.5% | ||
Case 3 | DTC Strategy |
•
Limp-home check | |
Threshold value |
•
Limp-home position > 13.1% or < 1.8% | ||
MIL On Condition |
•
1 driving cycle | ||
Fig. 1) Normal waveform of ETC motor & TPS1 at idle.
Fig. 2) Normal waveform of ETC motor & TPS1 with deceleration
