Dodge Ram 2004, Service Manual

Page: 33 / 642

rings, watchbands or bracelets that might make an
inadvertent electrical contact.
When diagnosing a body system problem, it is
important to follow approved procedures where
applicable. These procedures can be found in this
General Information Section or in the service man-
ual procedures. Following these procedures is very
important to the safety of individuals performing
diagnostic tests.
4.2.2 VEHICLE PREPARATION FOR
TESTING
Make sure the vehicle being tested has a fully
charged battery. If it does not, false diagnostic codes
or error messages may occur.
4.2.3 SERVICING SUB-ASSEMBLIES
Some components of the body system are in-
tended to be serviced as an assembly only. Attempt-
ing to remove or repair certain system sub-
components may result in personal injury and/or
improper system operation. Only those components
with approved repair and installation procedures in
the service manual should be serviced.
4.2.4 DRBIII
T
SAFETY INFORMATION
WARNING: EXCEEDING THE LIMITS OF THE
DRBIII
T
MULTIMETER IS DANGEROUS.
READ ALL DRBIII
T
INSTRUCTIONS BEFORE
USING THE MULTIMETER. FAILURE TO FOL-
LOW THESE INSTRUCTIONS CAN RESULT IN
PERSONAL INJURY OR DEATH.
• Follow the vehicle manufacturer’s service speci-
fications at all times.
• Do not use the DRBIII
t
if it has been damaged.
• Do not use the test leads if the insulation is
damaged or if metal is exposed.
• To avoid electrical shock, do not touch the test
leads, tips, or the circuit being tested.
•
Choose the proper range and functions for the
measurement. Do not try voltage or current mea-
surement that may exceed the rated capacity.
• Do not exceed the limits shown in the table below:
FUNCTION INPUT LIMIT
Volts 0 - 500 peak volts AC
0 - 500 volts DC
Ohms (resistance)* 0 -1.12 megohms
Frequency Measured
Frequency Generated 0 - 10 kHz
Temperature -58 - 1100°F
-50 - 600°C
* Ohms cannot be measured if voltage is present.
Ohms can be measured only in a non-powered
circuit.
•
Voltage between any terminal and ground must
not exceed 500v DC or 500v peak AC.
• Use caution when measuring voltage above 25v
DC or 25v AC.
•
Use the low current shunt to measure circuits up
to 10A. Use the high current clamp to measure
circuits exceeding 10A.
• When testing for the presence of voltage or cur-
rent, make sure the meter is functioning cor-
rectly. Take a reading of a known voltage or
current before accepting a zero reading.
• When measuring current, connect the meter in
series with the load.
•
Disconnect the live test lead before disconnecting
the common test lead.
• When using the meter function, keep the
DRBIII
t
away from spark plug or coil wires to
avoid measuring error from outside interference.
4.3 WARNINGS
4.3.1 VEHICLE DAMAGE WARNINGS
Before disconnecting any control module, make
sure the ignition is “off”. Failure to do so could
damage the module.
When testing voltage or continuity at any control
module, use the terminal side (not the wire end) of
the connector. Do not probe a wire through the
insulation; this will damage it and eventually cause
it to fail because of corrosion. Be careful when
performing electrical tests so as to prevent acciden-
tal shorting of terminals. Such mistakes can dam-
age fuses or components. Also, a second code could
be set, making diagnosis of the original problem
more difficult.
4.3.2 ROAD TESTING A COMPLAINT
VEHICLE
Some complaints will require a test drive as part
of the repair verification procedure. The purpose of
the test drive is to try to duplicate the diagnostic
code or symptom condition.
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GENERAL INFORMATION