A ml350 sports multi-purpose vehicle with an m276 3. 5v6 engine and 7 hand-held single-speed transformer was imported in 2012 at a mileage of approximately 135,000 km. Users report that when the car was used in the morning, it was found to have a low height。
Examination and analysis: maintenance staff check vehicle body height without abnormality; when the vehicle starts to move, adjust the switch to the detour height, the dashboard indicates that the vehicle is rising while the body height is slowly rising. Vehicle maintenance records were checked and no maintenance and repair records were available. The users were informed that the vehicle had been parked in the garage last night and that it had collapsed in the morning when it was used, at a low altitude; however, it had become normal since the start-up. Preliminary findings are occasional failures。
Rapid testing of vehicles with xentry resulted in a failure code 2c15664 in the air suspension control unit - a malfunction of the system pressure compressed air sensor and an unreliable signal. In terms of the failure code, it may be caused by the failure of the two-air suspension pressure sensors, the failure of the control unit or the failure of the line between them。
A guided test of the failure code resulted in a requirement to measure the sensor's power supply, iron-laying and signal voltage using a special tool switch box. The air suspension pressure sensor (figure 1) was measured on the circuit map, resulting in an electrical end of around 5. 0 v (standard 4. 8 to 5. 3 v) and an iron end of around 2. 9 v (standard 0. 5 to 4. 5 v) and normal。
Based on the results of the test, the guidance test requires the inspection of the conductor and plug-in of the air suspended pressure sensor to the control unit. Guides measuring y36b1 to n51/3 are well-guided, the plug-in is well connected, and there are no corrosive marks. Air suspension pressure sensor lines and plugs are normal. Aerodynamic tests of air compressors and pipes between compressors and valves are performed using xentry, which results in air compressors having a pressure above 1,400 kpa in a short period of time, and the air compressors and valves are properly sealed。
A combination of the above-mentioned checks indicates that the air suspension system is in normal condition and that failure detection is in jeopardy. Re-analysing the idea of testing, noting that the user reflects the low height of the vehicle, this detail relates to the rationale of the air hanger: the compressor units of the mercedes air suspension system incorporate air compressors and pressure-relief valves, which, when the air compressor or pressure-relief valves work, can be inflated or pumped from the air-reserver and gas tank, thus regulating the height of the vehicle。
Attempts were made to repeat the breakdown described by the user, by placing the vehicle in the workshop one night and observing the height of the vehicle the following day after work, but the failure did not occur. Aerodynamic testing of air compressors again is normal. The car went out for a test, and the car was running normally. The vehicle continued to be parked in the workshop and was intended to be placed for another night, although it was discovered that the rear height of the vehicle had been significantly reduced as it approached the end of work, and it was clear that there had been a leak in the airbag or the pipe that had been suspended. In this way, the direction of the inspection is shifted to the airway。
Raise the vehicle and use the air spring of xentry to activate two post-repressors one by one (figure 2), while allowing a technician to attend the corresponding air spring. As a result, no apparent leakage was made during the activation process. Following the activation of the two post-repressor air springs up to a higher point, foam water was carefully observed on the surface of the air springs and the corresponding air pipelines. No bubbles were found on the surface, indicating that there was no leak in the pipes and air springs。
Air compressors were subjected to aerodynamic tests, which did not result in pressure-building and no operational sound, i. E. The compressor was not working. Keep checking why the air compressor is not working. According to the circuit map of the compressor unit (figure 3), a9/1ml's electricity supply is controlled by the control unit through relay f58kt, while ironing through w52/11; the melting fuse f58f238 is used to prevent the compressor from being damaged by its excessive operation。
Air compressors are again subjected to aerodynamic tests and, during the tests, the plug-in of a9/ml is removed, measuring around 12. 0 v between their power supply and their ironing. This indicates that the compressor itself failed to function。
(b) troubleshooting: replacement of compressor and subsequent aerodynamic tests, with normal results. Two consecutive days of parking were not repeated. The vehicle was handed over to the user, who returned one week later by telephone, reflecting that the vehicle had been normal and that the failure had been completely eliminated。
