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.

8F - 40

STARTING

•

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.

STARTING

8F - 41

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.

8F - 42

STARTING

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

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)

221

Starter Mounting Bolts

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.

STARTING

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