AHLS provides driver with the best visibility by adjusting vertical direction of the headlamp. It consists of ECM, Linkage and actuator. The ECM detects the vehicle speed to use it a compensation factor for the actuator control. In other words, when the vehicle speed is low the acutator needs to repond slowly though the linkage of height sensor moves quickly ( reponse filter value is high ) .But when the vehicle speed is high, ECM operates the actuator quickly in proportion to the height sensor variation.
The ECM sets DTC C1212 if the speed signal line carries a higher frequency than defined maximum value( approx. 300Hz) for 2 seconds
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● Frequency check | ● Poor connection ● Vehicle speed sensor |
Detecting mode | ● every 20ms | |
Threshold value | ● Frequency >300Hz | |
Detecting time | ● 2 Sec |