2003 FORD MUSTANG battery

DIAGNOSIS AND TESTING
Starting System
Refer to Wiring Diagrams Cell
20 , Starting System for schematic and connector information.
Inspection and Verification WARNING: When servicing starter motor or carrying out other underhood work in the
vicinity of the starter motor, be aware that the heavy gauge battery input lead at the starter
solenoid is "electrically hot" at all times. A protective cap or boot is provided over this terminal
that must be installed after servicing. Be sure to disconnect the battery negative cable before
servicing the starter. Failure to follow these instructions may result in personal injury.
WARNING: When working in area of the starter motor, be careful to avoid touching hot
exhaust components. Failure to follow these instructions may result in personal injury.
WARNING: When using a remote starter switch or jumper wire, be sure the ignition switch
is in the OFF position and the transmission is in PARK (A/T) or Neutral (M/T) with the parking
brake control fully applied.
1. Verify the customers concern by operating the starting system to duplicate the conditions.
2. Inspect to determine if any of the following mechanical or electrical concerns apply.
3. If the inspection reveals an obvious concern that can be readily identified, repair as necessary.
4. If the concern remains after the inspection, determine the symptom. GO to Symptom Chart .
SECTION 303-
06: Starting System 2003 Mustang Workshop Manual Special Tool(s)
Digital Multimeter
105-
R0051 or equivalent Visual Inspection Chart
Mechanical Electrical
z
Starter motor
z Brackets z
Battery
z Battery junction box (BJB) fuse ignition switch (40A)
z Central junction box (CJB) Fuse 6 (20A)
z Fuse 24 (10A)
z Damaged wiring harness
z Starter Relay
z Loose or corroded connections Klj . 1 ba
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Symptom Chart
Pinpoint Tests
PINPOINT TEST A: THE ENGINE DOES NOT CRANK AND THE
RELAY DOES CLICK
SYMPTOM CHART Condition
Possible Sources Action
z The engine does
not crank and the
relay does click z
Battery.
z Fuse.
z Starter
motor/solenoid.
z Ignition switch.
z Circuit. z
Go To Pinpoint Test A .
z The engine does
not crank and the
relay does not
click z
Fuse.
z Battery.
z Starter relay.
z Ignition switch.
z Digital transmission
range (TR) sensor.
z Starter solenoid.
z Clutch pedal
position (CPP)
switch.
z Circuit. z
Go To Pinpoint Test B .
z The engine
cranks slowly z
Battery.
z Starter
motor/solenoid.
z Circuit. z
Go To Pinpoint Test C .
z Unusual starter
noise z
Starter motor
mounting.
z Starter motor.
z Incorrect starter
drive engagement. z
Go To Pinpoint Test D .
z The starter spins
but the engine
does not crank z
Starter Motor zINSPECT the starter motor
mounting and engagement.
REPAIR as necessary.
z Damaged
flywheel/ring gear
teeth. z
INSPECT the flywheel/ring
gear for damaged, missing or
worn teeth. REPAIR as
necessary. Test Step Result / Action to Take
A1 CHECK THE VOLTAGE TO THE STARTER RELAY
z
Measure the voltage between the starter relay pin 30,
circuit 1050 (LG/VT) and ground. Yes
GO to
A2 .
No
REPAIR circuit 1050 (LG/VT) Klj . 2 ba
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z
Is the voltage greater than 12.5 volts? for an open. TEST the
system for normal operation.
A2 CHECK THE VOLTAGE TO THE STARTER MOTOR
SOLENOID z
Measure the voltage between the starter motor solenoid
positive terminal and ground.
z Is the voltage 12.5 volts or greater? Yes
GO to
A3 .
No
REPAIR circuit 2037 (RD) for
an open. TEST the system
for normal operation. A3 MANUALLY JUMP THE STARTER MOTOR
z
Connect one end of a fused (15A) jumper wire to the
positive terminal of the battery and touch the other end to
the starter solenoid S- terminal.
z Does the starter solenoid engage? Yes
GO to
A4 .
No
INSTALL a new starter
motor. REFER to Starter Motor — 3.8L or
Starter Motor — 4.6L . TEST the
system for normal operation. A4 TEST THE STARTER MOTOR RELAY
z
Carry out the relay component test on the starter motor
relay. Refer to the relay component test in this section.
z Does the starter motor relay test good? Yes
REPAIR circuit 33
(WH/PK)/262 (BN/PK) for an
open. TEST the system for
normal operation.
No
INSTALL a new starter motor
relay. TEST the system for
normal operation. Klj . 3 ba
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PINPOINT TEST C: THE ENGINE CRANKS SLOWLY
PINPOINT TEST D: UNUSUAL STARTER NOISE z
Measure the resistance between the starter motor relay pin 86,
circuit 1205 (BK) and ground.
z Is the resistance less than 5 ohms? Test Step Result / Action to Take
NOTE:
Before beginning this test, be sure that the battery is tested and fully charged. C1 CHECK THE VOLTAGE TO THE STARTER
z
Key in OFF position.
z Measure the voltage between the starter motor
solenoid positive terminal and ground.
z Is the voltage 12.5 volts or greater? Yes
GO to
C2 .
No
REPAIR the circuit between the
battery and the starter solenoid.
CLEAN and TIGHTEN the
connections at the battery terminals.
TEST the system for normal
operation. C2 CHECK MOTOR GROUND CIRCUIT
z
Carry out the Motor Ground Circuit test; refer to
Component Tests in this section.
z Is the ground OK? Yes
INSTALL a new starter motor.
REFER to
Starter Motor — 3.8L or
Starter Motor — 4.6L . TEST the
system for normal operation.
No
REPAIR the ground circuit as
necessary. TEST the system for
normal operation. Test Step Result / Action to Take
D1 CHECK THE STARTER MOTOR
MOUNTING z
Inspect the starter motor mounting Yes Klj . 7 ba
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Component Tests
Starter Motor —Voltage Drop Test
WARNING: When servicing starter motor or carrying out other underhood work in the
vicinity of the starter motor, be aware that the heavy gauge battery input lead at the starter
solenoid is "electrically hot" at all times. A protective cap or boot is provided over this terminal
that must be installed after servicing. Be sure to disconnect the battery negative cable before
servicing the starter. Failure to follow these instructions may result in personal injury.
WARNING: When using a remote starter switch or jumper wire, be sure the ignition switch
is in the OFF position and the transmission is in PARK (A/T) or Neutral (M/T) with the parking
brake control fully applied.
Always make the Digital Multimeter connections at the component terminal rather than at the wiring
end connector. Making a connection at the wiring end connector could result in false readings because
the meter will not pick up a high resistance between the wiring connector and the component.
Starter Motor— Motor Feed Circuit
1. Make sure the battery is fully charged. Perform a battery load test. For additional information, refer to Section 414 - 00 .
2. Disconnect the inertia fuel shut off (IFS) switch.
3. Connect a remote starter switch between the starter solenoid S- terminal and the battery positive
(+) terminal.
4. Connect the Digital Multimeter positive lead to the battery positive (+) post. Connect negative lead to the starter solenoid M- terminal. brackets for cracks.
z Check the starter motor mounting
bolts for looseness.
z Is the starter motor mounted
correctly? GO to
D2 .
No
REINSTALL the starter motor correctly. REFER to
Starter Motor — 3.8L or
Starter Motor — 4.6L in this
section. D2 INSPECT THE STARTER MOTOR
z
Remove the starter motor; refer to
Starter Motor — 3.8L or
Starter Motor — 4.6L in this section.
z Inspect the starter motor for
damage.
z Is the starter motor damaged? Yes
INSTALL a new starter motor. REFER to
Starter Motor — 3.8L or
Starter Motor — 4.6L in this section.
TEST the system for normal operation.
No
CHECK the starter drive. REFER to Component
Tests, Starter Drive Test in this section. INSTALL a
new starter motor. TEST the system for normal
operation. Klj . 8 ba
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5. Engage the remote starter switch. Read and record the voltage. The voltage reading should be
0.5 volt or less.
6. If the voltage reading is less than 0.5 volts, go to the Starter Motor- Ground Circuit Component
Test.
7. If the voltage reading is greater than 0.5 volts, this an indication of excessive resistance in the connections, the positive battery cable or in the starter solenoid. Move the Digital Multimeter
negative lead to the starter solenoid B- terminal and repeat the test. If the voltage reading at the
B- terminal is less than 0.5 volts, the concern is either in the connections at the starter solenoid
or in the solenoid contacts. Go to Step 8. If the voltage reading is greater than 0.5 volts at the B-
terminal, the concern is either the positive battery cable or connections. Go to Step 9.
8. Remove the cables from solenoid B- , S- and M- terminals. Clean the cables and connections
and reinstall the cables to the correct terminals. Repeat Steps 3 through 6. If the voltage drop Item Part Number Description
1 — S-
terminal 2 — Remote starter switch
3 10653 Battery
4 — Digital multimeter
5 — B-
terminal 6 — M-
terminal Item Part Number Description
1 — S-
terminal 2 — Remote starter switch
3 10653 Battery
4 — Digital multimeter
5 — B-
terminal 6 — M-
terminal Klj . 9 ba
112003 Mustang Workshop Manual
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reading is still greater than 0.5 volts when checked at the M-
terminal and less than 0.5 volts
when checked at the B- terminal, the concern is in the solenoid contacts. Install a new starter
motor. Refer to Starter Motor — 3.8L or
Starter Motor — 4.6L .
9. Clean the positive (+) battery cable connections. Repeat the test at the starter solenoid B terminal. If the voltage is greater than 0.5 volts, install a new positive battery cable.
Starter Motor— Ground Circuit
A slow cranking condition can be caused by resistance in the ground or return portion of the cranking
circuit. Check the voltage drop in the ground circuit as follows:
1. Connect the Digital Multimeter positive lead to the starter motor housing (the connection must be clean and free of rust or grease). Connect the negative lead to the negative (- ) battery
terminal.
2. Engage the remote starter switch. Read and record the voltage. The voltage reading should be less than 0.3 volts.
3. If the voltage is greater than 0.3 volts, clean the negative cable connections at the battery, body ground connections, and the starter ground connections. Retest.
4. If the voltage is greater than 0.3 volts, install a new cable. If the voltage reading is less than 0.2 volts and the engine still cranks slowly, install a new starter motor. Refer to Starter Motor — 3.8L
or
Starter Motor — 4.6L . Item Part Number Description
1 105-
R0057 Digital multimeter
2 10653 Battery
3 — S-
terminal 4 — M-
terminal 5 — B-
terminal 6 — Remote starter switch Klj . 10 ba
112003 Mustang Workshop Manual
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REMOVAL AND INSTALLATION
Relay Switch
1. Disconnect the battery ground cable. For additional information, refer to Section 414 - 01 .
2. Remove the power distribution box cover.
3. Remove the starter relay from the power distribution box.
Installation 1. To install, reverse the removal procedure.
SECTION 303-
06: Starting System 2003 Mustang Workshop Manual Klj . 1 ba
22003 Mustang Workshop Manual
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