Ford Taurus, Руководство пользователя

Страница: 1035 / 2156

system; a careful inspection of components during testing is essential for quick
and accurate troubleshooting. Special, hand held computerized testers designed
specifically for diagnosing the system are available from a variety of aftermarket
sources, as well as from the vehicle manufacturer, but care should be taken to
assure that any test equipment being used is designed to diagnose that particular
computer controlled system accurately without damaging the computer control
module or other components being tested.
Pinpointing the exact cause of trouble in an electrical system
cansometimes only be accomplished by the use of special test
equipment. Thefollowing describes commonly used test equipment and
explains how to put it tobest use in diagnosis. In addition to the
information covered here, themanufacturer's instruction booklet
provided with the tester should be read andclearly understood before
attempting any test procedures.
TEST EQUIPMENT
Jumper Wires
Jumper wires are simple, yet extremely valuable, pieces of test equipment.
Jumper wires are simply wires that are used to bypass sections of a circuit. The
simplest type of jumper wire is merely a length of multi-strand wire with an
alligator clip at each end. Jumper wires are usually fabricated from lengths of
standard automotive wire and whatever type of connector (alligator clip, spade
connector or pin connector) that is required for the particular vehicle being
tested. The well equipped tool box will have several different styles of jumper
wires in several different lengths. Some jumper wires are made with three or
more terminals coming from a common splice for special purpose testing. In
cramped, hard-to-reach areas it is advisable to have insulated boots over the
jumper wire terminals in order to prevent accidental grounding, sparks, and
possible fire, especially when testing fuel system components.
Jumper wires are used primarily to locate open electrical circuits, on either the
ground (-) side of the circuit or on the hot (+) side. If an electrical component
fails to operate, connect the jumper wire between the component and a good
ground. If the component operates only with the jumper installed, the ground
circuit is open. If the ground circuit is good, but the component does not operate,
the circuit between the power feed and component is open. You can sometimes
connect the jumper wire directly from the battery to the hot terminal of the
component, but first make sure the component uses 12 volts in operation. Some
electrical components, such as fuel injectors, are designed to operate on about 4
volts and running 12 volts directly to the injector terminals can burn out the
wiring. By inserting an inline fuseholder between a set of test leads, a fused
jumper wire can be used for bypassing open circuits. Use a 5 amp fuse to provide
protection against voltage spikes. When in doubt, use a voltmeter to check the
voltage input to the component and measure how much voltage is being applied
normally. By moving the jumper wire successively back from the lamp toward the
power source, you can isolate the area of the circuit where the open is located.
When the component stops functioning, or the power is cut off, the open is in the
segment of wire between the jumper and the point previously tested.
CAUTION
NEVER use jumpers made from wire that is of lighter gauge than used
in thecircuit under test. If the jumper wire is of too small a gauge, it
Стр . 3 из 16 UNDERSTANDING AND TROUBLESHOOTING ELECTRICAL SYSTEMS
18.11.2005 http://www.chiltondiy.com/content/8687/8687_6_1.html