OTC Tools Code Scanner Manual Del Usuario página 5

The computer system in today's vehicles
does more than control engine operation
– it can help you find problems, too!
Special testing abilities are permanently
programmed into the computer by factory
engineers. These tests check the
components connected to the computer
which are used for (typically): fuel
delivery, idle speed control, spark timing
and emission systems. Mechanics have
used these tests for years. Now you can
do the same thing by using the Code
Scanner tool!
The engine computer runs the special
tests. The type of testing varies with
manufacturer, engine, model year etc.
There is no "universal" test that is the
same for all vehicles. The tests examine
INPUTS (electrical signals going IN to
the computer) and OUTPUTS (electrical
signals coming OUT of the computer.)
Input signals which have "wrong" values
or output circuits which don't behave
correctly are noted by the test program
and the results are stored in the
computer's memory. These tests are
important. The computer can not control
the engine properly if it has bad inputs or
outputs!
The test results are stored by using code
numbers, usually called "trouble codes"
or "service codes." For example, a code
63 might mean "throttle position sensor
signal voltage is too low." Code meanings
are listed in Sections 5 and 8. Specific
code definitions vary with manufacturer,
engine and model year, so you may want
to refer to a vehicle service manual for
additional information. These manuals
are available from the manufacturer,
other publishers or your local public
library. (See manual listing on page 6.)
You obtain trouble codes from the
engine computer memory by using the
Code Scanner tool. Refer to section 4
or 7 for details. After you get the
trouble codes, you can either:
• Have your vehicle professionally
serviced. Trouble codes indicate
problems found by the computer.
or,
• Repair the vehicle yourself using
trouble codes to help pinpoint the
problem.
To find the problem cause yourself, you
need perform special test procedures
called "diagnostics". These procedures
are in the vehicle service manual. There
are many possible causes for any
problem. For example, suppose you
turned on a wall switch in your home
and the ceiling light did not turn on. Is it
a bad bulb or light socket? Is the bulb
installed correctly? Are there problems
with the wiring or wall switch? Maybe
there is no power coming into the
house! As you can see, there are many
possible causes. The diagnostics written
for servicing a particular trouble code
take into account all the possibilities. If
you follow these procedures, you should
be able to find the problem causing the
code and fix it if you want to "do-it-
yourself."
The Code Scanner
ut
Using the Code Scanner to obtain
trouble codes is fast and easy.
5
t
t v
t