The mileage is about 70 thousand km, carrying the 6 stop manual transmission 2013 Volkswagen Golf 1.6. User response: sometimes the transmission failure lamp lights up when the vehicle is running, and at the same time, the symptom of acceleration is weak. Inspection and analysis: the maintenance personnel test the car, found that when the failure occurs, the impact of the gear is obvious, and the vehicle is starting with the 3 gear, which is the reason why the users feel the abnormal acceleration of the vehicle. Detection of transmission control unit, found fault code P2723-5, hydraulic control valve open circuit short circuit. After debugging the trouble code, the trouble code appears again after driving for about 5 min. Check transmission wiring harness, no damage to wiring harness or socket inlet. Check the circuit of the 5 oil pressure regulating solenoid valve according to the circuit diagram, measure the resistance between the foot of t52/18 and t14c/6 foot, and guide the normal, and measure the resistance between the foot of t52/30 and the foot of t14c/5, and it is also normal. In the process of checking the connector, it is found that the pin of t14c/5 pin is loosely coupled with the jack, which may lead to poor contact.