Logical Car Diagnosis

How logical diagnosis reveals car problems. Most car mechanics will perform a good visual inspection of the suspected problem areas before they formulate a plan of attack. Often this first step will uncover damage that is causing the complaint. 

Picture of car mechanic

Car Mechanic


An example of this is a key wiring harness chewed through by a rat. Small rodents seem to love the taste of wiring. They also find the warm engine compartment a nice place to build a home. These visitors can do a lot of damage in a short period of time. Performing a quick visual inspection may reveal signs of one of these engine compartment pets.

Sticks, leaves and branches along with other debris that you would not usually see in an engine compartment such as pieces of bread or trash is a tell tale sign that a rodent has visited. In some cases you may also see tiny pieces of plastic from wiring conduit or colored pieces of insulation mixed into this debris.


More than once I have found a nest in the heater compartment of an automobile. Often in the early winter the rodents will build a nest in the plastic compartment surrounding the heater core. Sometimes the driver’s complaint is an odor from the duct work that is more evident when the blower motor is running.

Car diagnostics mind set

Picture of engine thermostat

engine thermostat

When it comes to diagnosing car problems many driveway mechanics will ask the same question. Where do I start? This a good question and may have an impact on how much time and money you spend solving the car problem.

Car diagnostics boils down to problem solving. Begin with a detailed evaluation of the issue and think about things that might be in common. An example would be an overheating engine coupled with no heat inside the car. In this case the thermostat controls the engine cooling system but on some models also allows hot coolant to flow to the heater core.


Taking a few minutes before you begin to get a complete understanding of the complaint and putting together a short list of possible causes can be very helpful. Also don’t forget that a good quality service manual can keep you on track with symptom charts and diagnostic tree charts for specific problems such as a no start condition or check engine light.

Car repair diagnosis should be performed in an orderly manner and should not depend on guesswork, taking chances or even educated guessing. This next link takes you back to the homepage for online auto repair. There you can find out what kind of automotive help is available for driveway mechanics. You can also find more articles about automobile diagnostics on the blog about car repair.

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