Jeep 1996 Grand Cherokee Service Manual - page 266
receptacles. They should be properly installed and
tight. Repair or replace as required.
(3) Inspect the electrolyte level in the battery.
Replace battery if electrolyte level is low.
(4) Inspect generator mounting bolts for tightness.
Replace or tighten bolts if required. Refer to the Gen-
erator Removal/Installation section of this group for
torque specifications.
(5) Inspect generator drive belt condition and ten-
sion. Tighten or replace belt as required. Refer to
Belt Tension Specifications in Group 7, Cooling Sys-
tem.
(6)
Inspect automatic belt tensioner (if equipped).
Refer to Group 7, Cooling System for information.
(7) Inspect connections at generator field, battery
output, and ground terminals. Also check ground con-
nection at engine. They should all be clean and tight.
Repair as required.
CHARGING SYSTEM RESISTANCE TESTS
These tests will show the amount of voltage drop
across the generator output wire, from the generator
output (B+) terminal (Fig. 2) to the battery positive
post. They will also show the amount of voltage drop
from the ground (-) terminal on the generator (Fig. 2)
to the battery negative post.
A voltmeter with a 0–18 volt DC scale should be
used for these tests. By repositioning the voltmeter
test leads, the point of high resistance (voltage drop)
can easily be found.
PREPARATION
(1) Before starting test, make sure battery is in
good condition and is fully-charged. See Group 8A,
Battery for more information.
(2) Check condition of battery cables at battery.
Clean if necessary.
(3) Start the engine and allow it to reach normal
operating temperature.
(4) Shut engine off.
(5) Connect an engine tachometer.
(6) Fully engage the parking brake.
TEST
(1) Start engine.
(2) Place heater blower in high position.
(3) Turn on headlamps and place in high-beam
position.
(4) Turn vehicle interior lamps on.
(5) Start engine. Bring engine speed up to 2400
rpm and hold.
(6) Testing (+) circuitry:
(a) Touch the negative lead of voltmeter directly
to battery positive post.
(b) Touch the positive lead of voltmeter to the B+
output terminal stud on the generator (not the termi-
nal mounting nut). Voltage should be no higher than
0.6 volts. If voltage is higher than 0.6 volts, touch test
lead to terminal mounting stud nut and then to the
wiring connector. If voltage is now below 0.6 volts,
look for dirty, loose or poor connection at this point.
Also check condition of the generator output wire-to-
battery bullet connector. Refer to Group 8, Wiring for
connector location. A voltage drop test may be per-
formed at each (+) connection in this circuit to locate
the excessive resistance.
(7) Testing (-) circuitry:
(a) Touch the negative lead of voltmeter directly
to battery negative post.
(b) Touch the positive lead of voltmeter to the
ground terminal stud on the generator case (not the
terminal mounting nut). Voltage should be no higher
than 0.3 volts. If voltage is higher than 0.3 volts,
touch test lead to terminal mounting stud nut and
then to the wiring connector. If voltage is now below
0.3 volts, look for dirty, loose or poor connection at
this point. A voltage drop test may be performed at
each (-) connection in this circuit to locate the exces-
sive resistance. This test can also be performed
between the generator case and the engine. If test
voltage is higher than 0.3 volts, check for corrosion at
generator mounting points or loose generator mount-
ing.
Fig. 2 Generator Terminals
ZJ
CHARGING SYSTEM
8C - 3
DIAGNOSIS AND TESTING (Continued)