Dodge RAM TRUCK 1500 1995 Service Manual page 530

8W - 01 - 4 8W-01 GE1ERAL INFORMATION—WIRING DIAGRAMS
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(2) Avoid touching electrical terminals of the part,
unless instructed to do so by a written diagnostic
procedure.
(3) When using a voltmeter, be sure to connect the
ground lead first.
(4) Do not remove the part from its protective
packing until it is time to install the part.
(5) Before removing the part from its package,
ground the package to a known good ground on the
vehicle.
948W-193
Fig. 6 Electrostatic Discharge Symbol
TROUBLESHOOTING TOOLS
When diagnosing a problem in an electrical circuit
there are several common tools necessary. These tools
are listed and explained below,
• Jumper Wire - This is a test wire used to connect
two points of a circuit. It can be used to bypass an
open in a circuit.
WARNING: NEVER USE A JUMPER WIRE ACROSS
A LOAD, S U C H A S A MOTOR, CONNECTED B E ­
TWEEN A BATTERY F E E D AND GROUND.
© Voltmeter - Used to check for voltage on a circuit.
Always connect the black lead to a known good
ground and the red lead to the positive side of the
circuit.
CAUTION: Most of the electrical components used
in today's vehicle are solid state. When checking
voltages in these circuits use a meter with a 10-me-
gohm or greater impedance.
• Ohmmeter - Used to check the resistance between
two points of a circuit. Low or no resistance in a cir­
cuit means good continuity.
CAUTION: Most of the electrical components used
in today's vehicle are Solid State. When checking
resistance in these circuits use a meter with a 10-
megohm or greater impedance. In addition, make
sure the power is disconnected from the circuit.
Circuits that are powered up by the vehicle electri­
cal system can cause damage to the equipment and
provide false readings.
• Probing Tools - These tools are used for probing
terminals in connectors (Fig. 7). Select the proper
size tool from Special Tool Package 6807, and insert
it into the terminal being tested. Use the other end
of the tool to insert the meter probe.
SPECIAL TOOL
6801
PROBING
END 948W-233
Fig. 7 Probing Tool
INTERMITTENT AND POOR CONNECTIONS
Most intermittent electrical problems are caused by
faulty electrical connections or wiring. It is also pos­
sible for a sticking component or relay to cause a
problem. Before condemning a component or wiring
assembly check the following items.
• Connectors are fully seated
• Spread terminals, or terminal push out
® Terminals in the wiring assembly are fully seated
into the connector/component and locked in position
© Dirt or corrosion on the terminals. Any amount of
corrosion or dirt could cause an intermittent problem
• Damaged connector/component casing exposing the J
item to dirt and moisture
© Wire insulation that has rubbed through causing a
short to ground
• Wiring broke inside of the insulation
TROUBLESHOOTING TESTS
Before beginning any tests on a vehicle's electrical
system, use the Wiring Diagrams and study the cir­
cuit. Also refer to the Troubleshooting Wiring Prob­
lems section in this section.
TESTING FOR VOLTAGE
(1) Connect the ground lead of a voltmeter to a
known good ground (Fig. 8).
(2) Connect the other lead of the voltmeter to the
selected test point. The vehicle ignition may need to
be turned ON to check voltage. Refer to the appropri­
ate test procedure.
TESTING FOR CONTINUITY
(1) Remove the fuse for the circuit being checked
or, disconnect the battery.
(2) Connect one lead of the ohmmeter to one side
of the circuit being tested (Fig. 9).