With the introduction of computers, today’s automobiles have become more intelligent. New automobiles have more than 100 different electronic microprocessors to monitor and control various functions during normal vehicle operation. These microprocessors control items such as braking, fuel delivery, ignition timing, transmission shift points and many other functions. Computers also give automobiles the ability to diagnose problems. When a car’s on-board computer detects a problem, it will record a trouble code that indicates which system is not performing to specifications. Some codes can even tell you if one of the car’s sensors is malfunctioning.
Diagnostic procedure
-
- Read the instructions for the type of code scanner you have. There are many different types. Older cars have a scanner that makes the “Check Engine” light flash in a sequence that represents the code. For instance: flash flash space flash flash space flash flash flash space flash represents “2231.” The newer code scanners are digital and display the numerical trouble code on a screen. These newer scanners also have a built-in trouble code table so it can look up the trouble code for you.
- Locate the diagnostic connector on your vehicle. It is usually underneath the steering wheel or under the hood.
- Turn the ignition switch to the “On” position, but do not start the car.
- Plug the code scanner into the diagnostic connector and turn on the code scanner. The scanner will display the codes currently stored in the main computer.
- Repair the mechanical problem indicated by the trouble code on your car. Clear the trouble codes, unhook the code scanner, start the engine and let it warm up. Turn off, then reconnect the scanner and recheck the trouble codes.
Note:
- The code tells you only what area the problem is in. For example: if you get a trouble code for an oxygen sensor, the problem could be the oxygen sensor is bad, there is a short between the sensor and the computer or even that the computer could be bad.