Engine compartment
There are several reasons a vehicle or engine vibration could
cause an electrical complaint. Some of the things to check for
are:
●
Connectors not fully seated.
●
Wiring harness not long enough and is being stressed due
to engine vibrations or rocking.
●
Wires laying across brackets or moving components.
●
Loose, dirty or corroded ground wires.
●
Wires routed too close to hot components.
To inspect components under the hood, start by verifying the
integrity of ground connections. (Refer to GROUND INSPEC-
TION described later.) First check that the system is properly
grounded. Then check for loose connection by gently shaking
the wiring or components as previously explained. Using the
wiring diagrams inspect the wiring for continuity.
Behind the instrument panel
An improperly routed or improperly clamped harness can
become pinched during accessory installation. Vehicle vibration
can aggravate a harness which is routed along a bracket or near
a screw.
Under seating areas
An unclamped or loose harness can cause wiring to be pinched
by seat components (such as slide guides) during vehicle vibra-
tion. If the wiring runs under seating areas, inspect wire routing
for possible damage or pinching.
HEAT SENSITIVE
The owner’s problem may occur during hot weather or after car
has sat for a short time. In such cases you will want to check for
a heat sensitive condition.
To determine if an electrical component is heat sensitive, heat
the component with a heat gun or equivalent.
Do not heat components above 60°C (140°F). If incident
occurs while heating the unit, either replace or properly insulate
the component.
SGI842
Heating test
Heat gun
Do not heat above 60°C (140°F).
HOW TO PERFORM EFFICIENT DIAGNOSIS
FOR AN ELECTRICAL INCIDENT
Incident Simulation Tests (Cont’d)
GI-27