Chrysler RAM TRUCK 2500 1994 Service Manual page 330

• ELECTRICAL 8A - 1i
GENERATOR TEST PROCEDURES
INDEX
page
Diagnostic Procedures 15
General Information 15
Generator Output Test 16
GENERAL INFORMATION
The generator is belt-driven by the engine. All en­
gines use serpentine drive.
The amount of DC current produced by the gener­
ator is controlled by the powertrain control module
(PCM).
All vehicles are equipped with on-board diagnostics
(OBD). A l l O B D sensing systems are monitored by
the PCM. The PCM will store i n electronic memory
any detectable failure within the monitored circuits.
Refer to Using On-Board Diagnostic System i n this
group for more information.
OPERATIONAL CHECK WITH WOLTMETER
When the ignition switch is turned to the ON posi­
tion, battery potential will register on the voltmeter.
During engine cranking a lower voltage will appear
on the meter. With the engine running, a voltage
reading higher than the first reading (ignition i n ON)
should register.
DIAGNOSTIC PROCEDURES
I f the voltmeter does not give the indications as de­
scribed above, or i f an undercharged or overcharged
battery condition occurs, the following procedures
may be used to diagnose the charging system.
Remember that an undercharged battery is often
caused by:
• accessories being left on overnight.
• a defective switch which allows a bulb, such as a
trunk or glove box lamp, to stay on (refer to Ignition-
Off Draw Diagnosis).
VISUAL INSPECTION
• Inspect condition of battery cable terminals, bat­
tery posts, connections at engine block, starter motor
solenoid and relay. They should be clean and tight.
Repair as required.
• Inspect all fuses i n the fuseblock module for tight­
ness in receptacles. They should be properly installed
and tight. Repair or replace as required.
• Inspect generator mounting bolts for tightness. Re­
place or torque bolt as required (refer to Torque Spec­
ifications).
• Inspect generator drive belt condition and tension.
Tension or replace belt as required. Refer to Belt Ten­
sion Specifications.
page
Generator Output Wire Resistance Test 15
Operational Check with Voltmeter 15
• Inspect connection at generator B+ output. I t
should be clean and tight. Repair as required.
GENERATOR OUTPUT WIRE RESISTANCE TEST
Generator output wire resistance test (Fig. 1) will
show amount of voltage drop across generator output
wire between generator battery terminal and battery
positive post.
PREPARATION
(1) Before starting test, make sure vehicle has a
fully charged battery. Test and procedures on how to
check for a fully charged battery are shown i n Bat­
tery Test Procedures.
(2) Turn OFF ignition switch.
(3) Disconnect negative cable from battery.
(4) Disconnect generator output wire from genera­
tor output battery terminal.
(5) Connect a 0-150 ampere scale D.C. ammeter i n
series between generator battery terminal and dis­
connected generator output wire. Connect positive
lead to generator battery terminal and negative lead
to disconnected generator output wire.
(6) Connect positive lead of a test voltmeter (range
0-18 volts minimum) to disconnected generator out­
put wire. Connect negative lead of test voltmeter to
battery positive cable at positive post.
(7) Connect one end of a jumper wire to ground
and with other end probe K20 lead wire at back of
generator (Fig. 1). This will generate a DTC.
CAUTION: Do not connect A142 lead of wiring to
ground. Refer to Group 8W - Wiring Diagrams for
more information.
(8) Connect an engine tachometer and connect neg­
ative cable to battery.
(9) Connect a variable carbon pile rheostat between
battery terminals. Be sure carbon pile is in OPEN or
OFF position before connecting leads. See Load Testing
in Battery Test Procedures for instructions.
T E S T
(1) Start engine. Immediately after starting, re­
duce engine speed to idle.