DIAGNOSIS AND TESTING
Turn Signal and Hazard Lamps
Refer to Wiring Diagrams Cell
90 , Turn/Stop/Hazard Lamps for schematic and connector information.
Inspection and Verification 1. Verify the customer concern.
2. Visually inspect for the following obvious signs of mechanical and electrical damage.
3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
4. If the cause is not visually evident, verify the symptom and refer to the Symptom Chart.
Symptom Chart SECTION 417-
01: Exterior Lighting 2003 Mustang Workshop Manual Special Tool(s)
73 III Automotive Meter
105-
R0057 or equivalent
Visual Inspection Chart Mechanical Electrical
z
Multifunction switch z
Central junction box (CJB) Fuse 13 (15A).
z CJB Fuse 18 (15A).
z Circuitry
z Electronic flasher
z Turn signal/hazard lamp
Symptom Chart Condition
Possible Sources Action
z The turn signal
lamps are never
on z
Central junction
box (CJB) fuse 13
(15A).
z CJB Fuse 18
(15A).
z Circuitry.
z Multifunction
switch. z
Go To Pinpoint Test J . Klj . 1 ba
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DIAGNOSIS AND TESTING
Parking, Rear and License Lamps
Refer to Wiring Diagrams Cell
92 , Exterior for schematic and connector information.
Inspection and Verification 1. Verify the customer concern by operating the parking lamps.
2. Visually inspect for the following obvious signs of mechanical and electrical damage.
3. If the concern is not visually evident, determine the symptom and proceed to Symptom Chart.
Symptom Chart SECTION 417-
01: Exterior Lighting 2003 Mustang Workshop Manual Special Tool(s)
73 III Automotive Meter or
equivalent
105-
R0057
Visual Inspection Chart Mechanical Electrical
z
Damaged multifunction switch
(13K359)
z Damaged headlamp switch (11654) z
Blown battery junction box (BJB) Fuse 2
(30A)
z Damaged wiring harness
z Loose or corroded connections
z Damaged parking, rear or license lamp
Symptom Chart Condition
Possible Sources Action
z The parking, rear or license
lamps are inoperative z
BJB Fuse 2 (30A).
z Circuitry.
z Headlamp switch. z
GO to Pinpoint Test L .
z One or more parking, rear or
license bulbs(s) is inoperative z
Parking, rear or
license bulb(s).
z Circuitry. z
GO to Pinpoint Test M .
z The parking, rear or license
lamps are on continuously z
Headlamp switch.
z Circuitry. z
GO to Pinpoint Test N . Klj . 1 ba
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DIAGNOSIS AND TESTING
Fog Lamps
Refer to Wiring Diagrams Cell
86 , Fog Lamps for schematic and connector information.
Principles of Operation
The fog lamps will only illuminate when the low beam or parking lamps are illuminated. Voltage from
the parking lamp circuit is used to activate the fog lamp relay when the fog lamp switch is ON. Voltage
from the high beam headlamp circuit will activate the fog lamp interrupt relay. When the fog lamp
interrupt relay is active, the ground path is removed from the fog lamp relay, turning off the fog lamps.
Inspection and Verification 1. Verify the customer concern by operating the fog lamps.
2. Visually inspect for the following obvious signs of mechanical and electrical damage.
3. If the concern is not visually evident, determine the symptom and proceed to Symptom Chart.
Symptom Chart SECTION 417-
01: Exterior Lighting 2003 Mustang Workshop Manual Special Tool(s)
73 III Automotive Meter or
equivalent
105-
R0057
Visual Inspection Chart Mechanical Electrical
z
Damaged headlamp switch (11654)
z Damaged fog lamp switch
z Damaged multifunction switch
(13K359) z
Blown battery junction box (BJB) Fuse 27
(20A)
z Blown central junction box (CJB) Fuse 38
(20A)
z Damaged wiring harness
z Loose or corroded connections
z Damaged fog lamp relay
z Damaged fog lamp interrupt relay
z Damaged fog lamp
Symptom Chart Klj . 1 ba
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DIAGNOSIS AND TESTING
Reversing Lamps
Refer to Wiring Diagrams Cell
93 , Backup Lamps for schematic and connector information.
Inspection and Verification 1. Verify the customer concern by operating the reversing lamps.
2. Visually inspect for obvious signs of mechanical and electrical damage; refer to the following chart:
3. If the concern is not visually evident, determine the symptom and proceed to Symptom Chart.
Symptom Chart SECTION 417-
01: Exterior Lighting 2003 Mustang Workshop Manual Special Tool(s)
73III Automotive Meter or
equivalent
105-
R0057
Visual Inspection Chart Mechanical Electrical
z
Damaged digital transmission range (DTR)
sensor (automatic transmission [A/T])
z Damaged reversing lamp switch (manual
transmission [M/T]) z
Blown central junction box (CJB)
Fuse 11 (15A)
z Damaged wiring harness
z Loose or corroded connections
z Damaged reversing lamp
z Damaged DTR sensor (automatic
transmission [A/T])
z Damaged reversing lamp switch
(manual transmission [M/T])
Symptom Chart Condition
Possible Sources Action
z The reversing lamps are
inoperative z
CJB Fuse 11 (15A).
z Bulbs.
z Circuitry.
z DTR sensor (A/T).
z Reversing lamp
switch (M/T). z
GO to Pinpoint Test R . Klj . 1 ba
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4. If the concern remains after the inspection, connect the scan tool to the data link connector
(DLC) located beneath the instrument panel and select the vehicle to be tested from the scan
tool menu. If the scan tool does not communicate with the vehicle:
zcheck that the program card is correctly installed.
z check the connections to the vehicle.
z check the ignition switch position.
5. If the scan tool still does not communicate with the vehicle, refer to the scan tool manual.
6. Carry out the DATA LINK DIAGNOSTIC TEST. If the scan tool responds with: zCKT914, CKT915 or CKT70 = ALL ECUS NO RESP/NOT EQUIP, refer to Section 418 -
00 .
z NO RESP/NOT EQUIP for GEM, go to Pinpoint Test A.
z SYSTEM PASSED, retrieve and record the continuous diagnostic trouble codes (DTCs),
erase the continuous DTCs and carry out self- test diagnostics for the GEM.
7. If the DTCs retrieved are related to the concern, go to GEM Diagnostic Trouble Code (DTC) Index to continue diagnostics.
8. If no DTCs related to the concern are retrieved, proceed to Symptom Chart to continue diagnostics.
GEM Diagnostic Trouble Code (DTC) Index Visual Inspection Chart Mechanical Electrical
z
Switch(es) z
CJB Fuses:
„7 (20A)
„ 32 (15A)
„ 39 (5A)
z Wiring harness
z Connections
z Lamps
z Circuitry
GEM Diagnostic Trouble Code (DTC) Index DTC Description Source Action
B1322 Driver Door Ajar Circuit
Short to Ground GEM REFER to
Section 417 - 02 .
B1330 Passenger Door Ajar Circuit
Short to Ground GEM REFER to
Section 417 - 02 .
B1334 Decklid Ajar Rear Door
Circuit Short to Ground GEM REFER to
Section 417 - 02 .
B1342 ECU Is Defective GEM CLEAR the DTC. Retrieve the DTCs. If DTC B1342 is
retrieved, INSTALL a new GEM. For additional information, REFER to Section 419 - 10 .
B1397 Power Door unlock Circuit
Short to Battery GEM REFER to
Section 501 - 14B .
B1405 Driver Power Window Down
Circuit Short to Battery GEM REFER to
Section 501 - 11 . Klj . 3 ba
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Symptom Chart
Pinpoint Tests
CAUTION: Before removing and installing the GEM or its connectors, disconnect the Output Circuit Failure
B2488 RF Side Repeater Lamp
Output Circuit Failure GEM REFER to
Section 417 - 01 .
C1189 Brake Fluid Level Sensor
Input Short Circuit to Ground GEM REFER to
Section 413 - 01 .
C1223 Lamp Brake Warning
Output Circuit Failure GEM REFER to
Section 413 - 01 .
C1225 Lamp Brake Warning
Output Circuit Short to
Battery GEM REFER to
Section 413 - 01 .
Symptom Chart Condition
Possible Sources Action
z No communication with the generic
electronic module z
CJB Fuse 39
(5A)
z GEM.
z Circuitry. z
GO to
Pinpoint Test A .
z The courtesy lamps are inoperative zCJB Fuse 7
(20A).
z Door ajar switch
(es).
z Courtesy lamp
assemblies.
z Circuitry.
z GEM.
z Ignition Switch.
z Headlamp
Switch. z
GO to
Pinpoint Test B .
z The demand lighting is inoperative zCJB Fuse 7
(20A).
z Circuitry.
z GEM.
z Door ajar switch
(es).
z Demand lamp
assemblies.
z Ignition Switch.
z Headlamp
Switch. z
GO to
Pinpoint Test C .
z The illuminated entry is inoperative
when using the remote transmitter z
Remote
transmitter.
z GEM. z
GO to
Pinpoint Test D .
z The battery saver does not
deactivate after timeout z
Circuitry.
z GEM. z
GO to
Pinpoint Test E . Klj . 5 ba
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DIAGNOSIS AND TESTING
Daytime Running Lamps (DRL)
Refer to Wiring Diagrams Cell
97 , Daytime Running Lamps for schematic and connector information.
Principles of Operation
Daytime Running Lamps (DRL)
The daytime running lamps (DRL) system operates the low beam headlamps at a reduced intensity.
The DRL module (15A270) supplies pulse width modulated (PWM) voltage, approximately 75%- 92%
of battery voltage, to the low beam headlamps when the following conditions are met:
zThe parking brake control is released.
z The high beam headlamps are disabled.
z The ignition switch (11572) is in the RUN position.
The DRL module remains enabled when the low beam headlamps are turned on.
Inspection and Verification 1. Verify the customer concern by operating the system.
2. Visually inspect for obvious signs of mechanical and electrical damage.
3. Verify the headlamps are operating correctly. Correct any concerns before proceeding to the
SECTION 417-
04: Daytime Running Lamps 2003 Mustang Workshop Manual Special Tool(s)
73III Automotive Meter or
equivalent
105-
R0057
Visual Inspection Chart Mechanical Electrical
z
Damaged DRL module
z Damaged parking brake signal switch and
bracket (15A851) z
Blown battery junction box (BJB) Maxi-
Fuse FOG+DRL (20A)
z Damaged wiring harness
z Loose or corroded connection
z Damaged DRL module
z Damaged parking brake signal switch and
bracket Klj . 1 ba
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next step. For additional information, refer to
Section 417 - 01 .
4. Verify the parking brake control is fully released.
5. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
6. If the concern is not visually evident, verify the symptom and refer to the Symptom Chart.
Symptom Chart
Pinpoint Tests
PINPOINT TEST A: THE DAYTIME RUNNING LAMPS ARE
INOPERATIVE Symptom Chart Condition
Possible Sources Action
z The daytime running lamps are
inoperative z
BJB Maxi- Fuse
FOG+DRL (20A).
z Circuitry.
z Parking brake
signal switch and
bracket.
z DRL module. z
GO to
Pinpoint Test A .
z The daytime running lamps are
on with the parking brake set z
Circuitry.
z Parking brake
signal switch and
bracket.
z DRL module. z
GO to
Pinpoint Test B .
z The daytime running lamps are
on with the ignition switch off z
Circuitry.
z Ignition switch.
z DRL module. z
GO to
Pinpoint Test C .
z The low beam headlamps are on
at full intensity in DRL mode z
Circuitry.
z Headlamp switch.
z DRL module. z
GO to
Pinpoint Test D .
z The low beam headlamps are on
at reduced intensity with the
headlamp switch on z
Circuitry.
z Headlamp switch. z
REFER to
Section 417 -
01 .
Test Step Result / Action to Take
A1 CHECK THE PARKING BRAKE SWITCH SIGNAL
CIRCUIT TO THE DRL MODULE FOR SHORT TO GROUND NOTE:
Verify the parking brake control is fully released
for this step.
z Key in OFF position.
z Disconnect: DRL Module C1030.
z Measure the resistance between DRL module C1030 Pin
6, Circuit 22 (LB/BK), harness side and ground. Yes
GO to
A3 .
No
GO to A2 . Klj . 2 ba
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