What is the basic idea of automobile fault diagnosis

First of all, do not blindly disassemble and replace parts. For electronic failures, first use the computer to check the fault code, and then check the data flow, and then according to the fault code of the damaged parts and accessories to make a preliminary judgment, and then carry out repairs (check the circuit diagram in special cases). Mechanical failure should first check the appearance of deformation or damage, debugging should be experienced technicians to make a preliminary judgment of abnormal noise, and then carefully check.

Automotive troubleshooting refers to the detection, analysis and judgment of determining the technical condition of the car or identifying the location and cause of the fault without disassembling it (or unloading only individual small parts) when the car has hidden problems, deterioration of its technical condition, or partial or complete loss of working ability.

In automotive fault diagnosis, often use some diagnostic parameters to characterize the technical state of the car, assembly and institutions, such as the car's work process parameters and the state parameters accompanying the work process. These parameters include physical quantities (e.g., vibration, noise, temperature, vacuum, power, cylinder compression pressure, etc.) and chemical quantities (e.g., exhaust gas composition, lubricant impurity composition, etc.). .

Changes in these diagnostic parameters can correspond to changes in the technical condition of the vehicle with high reliability, sensitivity and realizability. In order to quantitatively evaluate these parameters, it is necessary to establish standards for diagnostic parameters, such as national standards for automobile driving safety and emissions, manufacturer's recommended standards related to technical conditions, and local and enterprise standards suitable for different regions and conditions of use.