2011 Volkswagen CC sedan with 2.0TCGM engine. After the car changed the right front light assembly because of the accident collision, the light energy of the light lamp was lit, but the right front lamp self-examination function disappeared, and the basic setting failure of the headlamp could not be carried out. Check analysis: connect the diagnostic instrument VAS6150, re code the control unit, but the code can not be accepted; enter the headlamp automatic vertical control system diagnosis interface, do not display the basic information such as the right headlight part number. Analyze the cause of failure and make the following test according to the circuit diagram. (1) the failure of the iron lap. Check the right front headlights T14e/7 and T14e/5 terminals and the tie point 685 between the normal line, re grinding the grounding point installation, the fault is still. (2) coding error. Compared with the same type of vehicle replication code, but can not be included. (3) the new headlights malfunction. Because the headlamp assembly involved in the electronic circuit can not be measured, the replacement test was carried out to eliminate the failure caused by the new parts. (4) failure of power supply. Check the right light fuse SC8 (10 A) normal, detect the fuse SC8 to the right front light T14e/4 terminal line between the circuit, find the circuit short circuit, so determine the power supply part of the fault. Troubleshooting: after repairing the short circuit line, the lighting system is basically set up and troubleshooting. The cause of the failure is that the control unit of the control unit can not work because of the lack of power supply in the control unit of the right front light, and the part coding and basic setting can not be identified.