Jeep Grand Cherokee WK. Manual — part 372
TESTING
COLD CRANKING TEST
For complete starter wiring circuit diagrams, refer to 8,
Wiring Diagrams. The battery must be fully-charged
and load-tested before proceeding. Refer to Battery in
Battery.
1. Connect volt-ampere tester to battery terminals (1),
(2) and (3). See instructions provided by manufac-
turer of volt-ampere tester being used.
2. Fully engage parking brake.
3. Place gearshift selector lever in Park position.
4. Verify that all lamps and accessories are turned off.
5. To prevent a gasoline engine from starting, remove
Automatic ShutDown (ASD) relay. To prevent a die-
sel engine from starting, remove Fuel Pump Relay.
These relays are located in Power Distribution
Center (PDC). Refer to label on PDC cover for
relay location.
6. Rotate and hold ignition switch in Start position. Note cranking voltage and current (amperage) draw readings
shown on volt-ampere tester.
a. If voltage reads below 9.6 volts, refer to Starter Motor in Diagnosis and Testing. If starter motor is OK, refer
to Engine Diagnosis in 9, Engine for further testing of engine. If starter motor is not OK, replace faulty
starter motor.
b. If voltage reads above 9.6 volts and current (amperage) draw reads below specifications, refer to Feed Cir-
cuit Test in this section.
c. If voltage reads 12.5 volts or greater and starter motor does not turn, refer to Control Circuit Testing in this
section.
d. If voltage reads 12.5 volts or greater and starter motor turns very slowly, refer to Feed Circuit Test in this
section.
NOTE: A cold engine will increase starter current (amperage) draw reading, and reduce battery voltage
reading.
FEED CIRCUIT TEST
The starter feed circuit test (voltage drop method) will determine if there is excessive resistance in high-amperage
feed circuit. For complete starter wiring circuit diagrams, refer 8, Wiring Diagrams.
When performing these tests, it is important to remember that voltage drop is giving an indication of resistance
between two points at which voltmeter probes are attached.
Example: When testing resistance of positive battery cable, touch voltmeter leads to positive battery cable clamp
and cable connector at starter solenoid. If you probe positive battery terminal post and cable connector at starter
solenoid, you are reading combined voltage drop in positive battery cable clamp-to-terminal post connection and
positive battery cable.
The following operation will require a voltmeter accurate to 1/10 (0.10) volt. Before performing tests, be certain that
following procedures are accomplished:
•
Battery is fully-charged and load-tested. Refer to Battery in 8, Battery.
•
Fully engage parking brake.
•
Place gearshift selector lever in Park position.
•
Verify that all lamps and accessories are turned off.
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•
To prevent a gasoline engine from starting, remove Automatic ShutDown (ASD) relay. To prevent a diesel
engine from starting, remove Fuel Pump Relay. These relays are located in Power Distribution Center (PDC).
Refer to label on PDC cover for relay location.
1. Connect positive lead of voltmeter (1) to negative
battery cable terminal post. Connect negative lead
of voltmeter to negative battery cable clamp.
Rotate and hold ignition switch in Start position.
Observe voltmeter (1). If voltage is detected, cor-
rect poor contact between cable clamp and termi-
nal post.
2. Connect positive lead of voltmeter (1) to positive
battery terminal post. Connect negative lead of
voltmeter to battery positive cable clamp. Rotate
and hold ignition switch in Start position. Observe
voltmeter (1). If voltage is detected, correct poor
contact between cable clamp and terminal post.
3. Connect voltmeter (2) to measure between battery
positive terminal post and starter solenoid battery
terminal stud (3). Rotate and hold ignition switch in
Start position. Observe voltmeter. If reading is
above 0.2 volt, clean and tighten battery cable con-
nection at solenoid. Repeat test. If reading is still
above 0.2 volt, replace faulty positive battery cable.
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4. Connect voltmeter (1) to measure between nega-
tive battery terminal post and a good clean ground
on engine block (3). Rotate and hold ignition switch
in Start position. Observe voltmeter. If reading is
above 0.2 volt, clean and tighten negative battery
cable attachment on engine block. Repeat test. If
reading is still above 0.2 volt, replace faulty nega-
tive battery cable.
5. Connect positive lead of voltmeter (3) to starter
housing (1). Connect negative lead of voltmeter to
negative battery terminal post. Rotate and hold
ignition switch in Start position. Observe voltmeter.
If reading is above 0.2 volt, correct poor starter to
engine block ground contact.
6. If equipped with dual battery system (certain diesel
equipped models), connect positive lead of voltme-
ter to positive battery cable clamp on battery
located on left side of vehicle. Connect negative
lead of voltmeter to positive battery terminal post
on battery located on right side of vehicle. Rotate
and hold ignition switch in Start position. Observe
voltmeter. If reading is above 0.2 volt, clean and
tighten battery cables at both batteries. Repeat
test. If reading is still above 0.2 volt, replace faulty positive battery cable.
If resistance tests detect no feed circuit problems, refer to Starter Motor in the Diagnosis and Testing.
CONTROL CIRCUIT TESTING
The starter control circuit components should be tested in the order in which they are listed, as follows:
•
Starter Relay - Refer to Starter Relay Diagnosis and Testing.
•
Starter Solenoid - Refer to Starter Motor Diagnosis and Testing.
•
Ignition Switch - Refer to Ignition Switch and Key Lock Cylinder
•
Park/Neutral Position Switch - Refer to Park/Neutral Position Switch in 21, Transmission.
•
Wire harnesses and connections - Refer to 8, Wiring Diagrams.
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SPECIFICATIONS
STARTING SYSTEM
Starter Motor and Solenoid
Engine Application
3.7L
4.7L
5.7L
Manufacturer
Denso
Part Number
56044734AA
56044735AB
56044736AB
Power Rating
1.2 Kilowatt / 1.6
Horsepower
1.2 Kilowatt / 1.6
Horsepower
1.4 Kilowatt / 1.9
Horsepower
Voltage
12 Volts
Number of Brushes
4
Drive Type
Gear Reduction
Free Running Test Voltage
11 Volts
Free Running Test Amperage
Draw
73 Amperes
Free Running Test Minimum
Speed
3601 rpm
Solenoid Closing Maximum
Voltage Required
7.5 Volts
* Cranking Amperage Draw
Test
125 - 250 Amperes
* Test at operating temperature. Cold engine, tight (new) engine, or heavy oil will increase starter amperage draw.
SPECIFICATIONS - TORQUE - STARTING SYSTEM
DESCRIPTION
N·m
Ft. Lbs.
In. Lbs.
Battery Cable Eyelet Nut
at Solenoid (large nut)
25
19
221
Starter Mounting Bolts
68
50
-
STARTER
DIAGNOSIS AND TESTING - STARTER MOTOR
Correct starter motor operation can be confirmed by performing the following free running bench test. This test can
only be performed with starter motor removed from vehicle. Refer to Specifications for starter motor specifications.
1. Remove starter motor from vehicle. Refer to Starter Motor Removal and Installation.
2. Mount starter motor securely in a soft-jawed bench vise. The vise jaws should be clamped on the mounting
flange of starter motor. Never clamp on starter motor by field frame.
3. Connect a suitable volt-ampere tester and a 12-volt battery to starter motor in series, and set ammeter to 100
ampere scale. See instructions provided by manufacturer of volt-ampere tester being used.
4. Install jumper wire from solenoid terminal to solenoid battery terminal. The starter motor should operate. If starter
motor fails to operate, replace faulty starter motor assembly.
5. Adjust carbon pile load of tester to obtain free running test voltage. Refer to Specifications for starter motor free
running test voltage specifications.
6. Note reading on ammeter and compare reading to free running test maximum amperage draw. Refer to Speci-
fications for starter motor free running test maximum amperage draw specifications.
7. If ammeter reading exceeds maximum amperage draw specification, replace faulty starter motor assembly.
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