Automotive diagnostics

When it comes to diagnosing car problems many Diy auto mechanics will ask the same question. Where do I start?

Not only is this a good question but it will have a direct impact on the overall diagnostic time you spend solving the car problem.

automotive engine diagnosis

engine diagnosis

Automotive diagnostics begins with the procedure of problem solving. You begin with a detailed evaluation of the automobile problem.

Take a few minutes before you begin to get a complete understanding of the complaint or malfunction. Automotive diagnostics should be performed in an orderly manner and should not depend on guesswork, taking chances or even educated guessing.

Let’s try an example of the above process using a common car problem. Say your vehicle has a left front marker light out. The right side works normally and comes on and off with the headlight switch. The hard facts of our situation lead us to a very logical path of diagnosis.

With the headlight switch working and the right side marker lamp coming on checking the fuses and circuit breakers would not seem to be the right first step. Also the headlight switch seems to functioning OK at this time.

In fact the most common cause of this situation would be a simple blown bulb. But let’s not go to the online auto parts store for a replacement bulb just yet.


Let’s remove the marker lamp bulb and test for power and ground at the lamps socket. You may find that there is a poor or corroded connection at the bulb socket itself. Or you may find that there is power at the marker lamp, but no ground.

Even though the above situation is oversimplified, automotive diagnostics should be tackled in the same manner. Use the facts of the car problem to guide you in your first few diagnostic steps.

When you feel that you have found the bad car part take the extra step and test that component to verify it has failed. In my opinion there is nothing worse than spending money on unneeded car parts.

Escort Radar

Diagnosing car problems

fuelinjector diagnosis

Fuel injection Diagnosis

Keeping your eyes open and your mind open as well is also a valuable skill for diy car mechanics when performing automotive diagnostics.

The visual inspection can reveal many unexpected possible causes for your car problems.

Most automotive mechanics will perform a good visual inspection of the related systems before they break out any diagnostic repair diagrams.

Often this first step will uncover damage that is causing the complaint with the vehicle. A quick example of this is a wiring harness chewed through by a small animal.

In my 25 years as an auto mechanic I have seen this hundreds of times. I have no idea why rodents love the taste of car wiring but they do.

When the mouse partially chews through many wires servicing several different components strange almost bazaar symptoms can result.

Actually discovering the damage with the naked eye in this situation may also be part luck. Many times wiring damage will happen in places only the tiny animals can get to.

Many times I have removed interior panels and uncovered a nest. On a few occasions the residents of the nest were present and needed to be relocated.

This next link takes you back to the homepage. Here you can find out what kinds of automotive stuff are available on this website. Also find more automotive diagnostics information for Diy car repair.


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