Service Guide: How to Start Car Diagnostics and Troubleshooting

At present, level of electronics in cars is getting higher and higher, and diagnosing its malfunctions is becoming increasingly difficult. The cause of failure may be electronic control system, or there may be a problem with other parts outside electronic control system. Therefore, the complexity of troubleshooting is also different. If you follow some basic principles of fault diagnosis, you can quickly find a fault with less labor and material resources:

Service Guide: How to Start Car Diagnostics and Troubleshooting

(1) First outside, then inside.

In event of an engine failure, first check for possible faulty parts other than electronic control system.

This avoids a malfunction that is not related to electronic control system. However, testing sensors, ECUs, actuators, and system circuits is a complex and time-consuming task. The real fault may be easier to find, but impossible to find.

(2) Simplify first, then complicate.

Possible defective parts that can be checked in a simple way should be checked first. For example, visual inspection is easiest, you can use it to see (use your eyes to see if chain is loose or broken, if there is oil leakage in oil circuit, if there is damage or air leakage in intake pipe, etc.) , touch (touch suspicious line connector with your hand) Whether connection is loose, feel temperature of spark plug and vibration of fuel injector to determine if spark plug and fuel injector are working, feel if there is an abnormally high temperature at connection to line to determine if if there is a bad connection, etc.), listen (Use your ears or with screwdrivers, stethoscopes, etc. to listen for sound of air leakage, if there is any strange noise in engine, if there is a regular click of fuel injector etc.) and other methods of visual inspection. Faults are detected quickly.

Service Guide: How to Start Car Diagnostics and Troubleshooting

When a visual inspection does not find a fault, but must be checked with instruments, meters or other special tools, one should also check first of all what is easier to check. Check items that can be tested for food first.

(3) Ripe first.

Due to design and operating conditions, some engine failures may be most common failures of certain components or components. These common faults should be checked first. In this way, faults can often be found quickly, saving time and effort.

(4) Write code first.

Electronic control systems usually have a self-diagnostic function for faults. When a certain fault occurs in electronic control system, fault self-diagnosis system immediately detects fault and warns driver with warning lights such as "Check Engine". ". In this case, fault information is stored as a code. But for some faults, self-diagnosis fault system only stores fault code and does not report to police. Therefore, before checking engine system, you should read fault code in accordance with method provided by manufacturer, and also check and repair fault indicated by code After fault indicated by fault code has been rectified, if the phenomenon of engine failure has not been rectified.

Service Guide: How to Start Car Diagnostics and Troubleshooting

Or no fault code is displayed at beginning, then check for possible faulty engine parts.

(5) Think before you act.

Fault analysis for engine failure should be performed first, and then a fault check should be performed based on an understanding of possible causes of fault. In this way, blind inspection of faults can be avoided: invalid inspection will not be performed on parts that have nothing to do with fault phenomenon, and missed inspections of some relevant parts can be avoided.

(6) Reserve first, then use.

The good or bad performance of some components of electronic control system, and health of electrical circuit is often determined by its voltage or power

Resistance and other parameters to evaluate. In absence of such data, detection of system failure will be very difficult, and often only method of replacement with new parts can be adopted, which leads to a sharp increase in maintenance costs and time costs. The so-called standby before use means that when vehicle is overhauled, maintenance data relating to maintenance model must be prepared. In addition to collecting and organizing this maintenance data from service manuals and professional books, another effective way is to measure and record relevant parameters of same system of same type of trouble-free vehicle. If you usually pay attention to doing this job well, it will make it easier to check system for faults.

In short, above principles should be used flexibly. Only by spending less human and material resources, it is possible to quickly and accurately determine nature and possible causes of malfunction. Only then can a reasonable diagnostic process be formulated. Satisfactory Solution Restore proper operational and technical parameters of vehicle.