Jeep 1997 Grand Cherokee Service Manual page 323

POSITIVE CLAMP
ZG
DIAGNOSIS AND TESTING (Continued)
COLD CRANKING TEST
For circuit descriptions and diagrams, refer to
8W-21 - Starting System in Group 8W - Wiring Dia-
grams. The battery must be fully-charged and load-
tested before proceeding. Refer to Group 8A - Battery
for more information.
(1) Connect a suitable volt-ampere tester to the
battery terminals (Fig. 1). Refer to the operating
instructions provided with the tester being used.
Fig. 1 Volts-Amps Tester Connections - Typical
(2) Fully engage the parking brake.
(3) If the vehicle is equipped with an automatic
transmission, place the gearshift selector lever in the
Park position. If the vehicle is equipped with a man-
ual transmission, place the gearshift selector lever in
the Neutral position and fully depress the clutch
pedal.
(4) Verify that all lamps and accessories are
turned off.
(5) Unplug the Automatic ShutDown (ASD) relay
to prevent a gasoline engine from starting. The ASD
relay is located in the Power Distribution Center
(PDC). Refer to the PDC label for ASD relay identi-
fication and location. To prevent a diesel engine from
starting, unplug the fuel shut off solenoid wire har-
ness connector (Fig. 2).
(6) Rotate and hold the ignition switch in the Start
position. Note the cranking voltage and current
(amperage) draw.
(a) If the voltage reads below 9.6 volts, remove
the starter for bench testing. If the starter bench
test is OK, refer to Group 9 - Engine for further
diagnosis of the engine. If the starter bench test is
not OK, replace the faulty starter.
(b) If the voltage reads above 9.6 volts and the
current (amperage) draw reads below specifica-
tions, see the Feed Circuit Test procedures in this
group.
INDUCTION AMMETER NEGATIVE CLAMP CLAMP FUEL GENERATOR
Fig. 2 Fuel Shut Off Solenoid Connector- Diesel
the starter does not turn, see the Control Circuit
Test procedures in this group.
the starter turns very slowly, see the Feed Circuit
Test procedures in this group.
NOTE: A cold engine will increase the starter cur-
rent (amperage) draw reading, and reduce the bat-
tery voltage reading.
FEED CIRCUIT TEST
The starter feed circuit test (voltage drop method)
will determine if there is excessive resistance in the
high-amperage circuit. For circuit descriptions and
diagrams, refer to 8W-21 - Starting System in Group
8W - Wiring Diagrams.
When performing these tests, it is important to
remember that the voltage drop is giving an indica-
tion of the resistance between the two points at
which the voltmeter probes are attached.
Example: When testing the resistance of the bat-
tery positive cable, touch the voltmeter leads to the
battery positive cable clamp and the cable connector
at the starter solenoid. If you probe the battery pos-
itive terminal post and the cable connector at the
starter solenoid, you are reading the combined volt-
age drop in the battery positive cable clamp-to-termi-
nal post connection and the battery positive cable.
The following operation will require a voltmeter
accurate to 1/10 (0.10) volt. Before performing the
tests, be certain the following procedures are accom-
plished:
SHUT-OFF FUEL INJECTOR PUMP FUEL SHUT-OFF SOLENOID CONNECTOR SOLENOID
STARTING SYSTEMS
Engine
(c) If the voltage reads 12.5 volts or greater and
(d) If the voltage reads 12.5 volts or greater and
FWD
8B - 5