The Electronic Throttle Control(ETC) system's components are the 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 PCM to control the throttle motor in order to control the throttle valve opening angle properly in response to the driving condition.
PCM sets DTC P0638 if the PCM detects TPS adaptation value exceeds threshold value.
Item | Detecting Condition | Possible Cause | |
DTC Strategy | Case1 |
•
TPS adaptation condition check | 1. Poor connection or damaged harness 2. Faulty ETC Motor 3. Faulty TPS |
Case2 |
•
ETC Limp Home position check | ||
Case3 |
•
Lower mechanical stop adaptation voltage range check | ||
Enable Conditions |
•
During TPS adaptation | ||
Threshold Value | Case1 |
•
TPS adaptation is requested but not possible | |
Case2 |
•
Difference between Throttle sensor voltage in limphome and limphome setpoint > 0.3V | ||
Case3 |
•
Difference between Throttle sensor voltage in lower mechanical stop position and lower mechanical stop position setpoint > 0.3V | ||
Diagnostic Time |
•
1.2 sec. | ||
Limp-Home |
•
Forced limited RPM mode : The PCM limits engine speed to 1500rpm
•
Electrical check of the ETC system is prohibited | ||
MIL On Condition |
•
Immediate | ||
