2003 FORD MUSTANG brake

The boost pressure gauge on the instrument cluster receives and measures the boost pressure
directly from the intake manifold. The boost pressure gauge will display between 0.0-
0.48 kpa (0.0-10
psi) boost pressure dependent upon accelerator position, engine load, and engine rpm.
LOW FUEL Level Indicator
The low fuel level indicator is hardwired from the fuel sender to the instrument cluster. The instrument
cluster will illuminate the low fuel indicator when the usable fuel quantity is less than 1/8 tank (15%) of
fuel tank capacity.
Oil Pressure Gauge
The oil pressure gauge is hardwired from the oil pressure switch to the instrument cluster. The oil
pressure gauge will indicate either normal or no oil pressure.
CHECK FUEL CAP
The CHECK FUEL CAP indicator is used to indicate significant leaks in the fuel tank evaporative
system due to a loose fuel cap. Fuel tank pressure is monitored by the PCM. If a leak is detected the
PCM signals a fault to the instrument cluster via the SCP network. Once the PCM has detected a
loose fuel cap and the CHECK FUEL CAP indicator is illuminated, the indicator will remain illuminated
until the fuel cap is secured and the vehicle has been running for several minutes. For additional
information, refer to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.
BRAKE Warning Indicator
The BRAKE warning indicator activates when the generic electronic module (GEM) detects the ignition
switch circuits are in the RUN state, when the GEM detects low brake fluid level, or that the parking
brake is applied. The BRAKE warning indicator will prove out starting when the GEM detects that the
ignition circuits have made a transition to RUN or START from OFF, ACC, or keyout and ending when
either three seconds have elapsed or when the GEM detects the ignition circuits have made a
transition to OFF, ACC, or keyout.
Safety Belt Warning Indicator
The safety belt switch is hardwired to the GEM. The safety belt warning indicator will be illuminated
when the GEM sends a ground signal to the instrument cluster.
ABS Warning Indicator
The ABS warning indicator will be illuminated when the anti- lock brake control module sends a ground
signal to the instrument cluster. The prove- out of the ABS indicator is controlled by the anti- lock brake
control module.
SERVICE ENGINE SOON Indicator
The SERVICE ENGINE SOON indicator receives its signal from the PCM over the SCP network. If the
instrument cluster does not receive a message from the PCM within five seconds, the instrument
cluster will illuminate the SERVICE ENGINE SOON indicator and log a diagnostic trouble code (DTC).
High Beam Indicator
The high beam indicator will illuminate when the steering column multifunction switch is in the high
beam position by sending a battery signal to the instrument cluster. Right and Left Turn Indicator Klj . 3 ba
412003 Mustang Workshop Manual
18. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_5108/S3B~us~en~ ...

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 concern remains after the inspection, connect the diagnostic tool to the data link connector (DLC) located beneath the instrument panel and select the vehicle to be tested from the
diagnostic tool menu. If the diagnostic 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 diagnostic tool still does not power up, refer to the diagnostic tool operating manual.
6. Carry out the DATA LINK DIAGNOSTICS test. If the diagnostic tool responds with: zCKT914, CKT915 OR CKT70 = ALL ECUS NO RESP/NOT EQUIP, refer to Section 418 -
00 .
z NO RESP/NOT EQUIP for the instrument cluster, Go To Pinpoint Test A or for the
generic electronic module (GEM), Go To Pinpoint Test W .
z SYSTEM PASSED, retrieve and record the continuous diagnostic trouble codes (DTCs),
erase the continuous DTCs and carry out the self- test diagnostics for the instrument
cluster or the GEM.
7. If the DTCs retrieved are related to the concern, go to the Instrument Cluster Diagnostic Trouble Code (DTC) Index or the GEM Diagnostic Trouble Code Index to continue diagnostics.
8. If no DTCs related to the concern are retrieved, proceed to the Symptom Chart to continue diagnostics.
Instrument Cluster Self- Diagnostic Mode
To enter the instrument cluster self- diagnostic mode, press and hold the instrument cluster
SELECT/RESET button, turn the ignition switch to the RUN position, and then continue pressing the
SELECT/RESET button (five seconds) until tESt is displayed in the odometer. The SELECT/RESET
button must be released within three seconds of the odometer tESt display to begin the self- diagnostic
mode. Press the SELECT/RESET button to advance through the following steps until dtc is displayed.
Depressing the SELECT/RESET button will display any stored continuous DTCs before proceeding to
the next step. z
Engine coolant level
z Accessory drive belt
z Engine oil level
z Parking brake position switch
z Brake fluid level
z Boost gauge pressure line „
5 (15A)
„ 7 (15A)
„ 11 (15A)
„ 13 (15A)
„ 21 (5A)
„ 23 (15A)
„ 24 (30A)
„ 29 (15A)
„ 30 (15A)
„ 32 (15A)
„ 34 (20A)
„ 35 (15A)
„ 37 (5A)
„ 38 (20A)
„ 39 (5A)
z Circuitry Klj . 5 ba
412003 Mustang Workshop Manual
18. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_5108/S3B~us~en~ ...

GEM Diagnostic Trouble Code (DTC) Index
DTC Description Source Action
B1218 Horn Relay Coil Circuit Short to
VBatt GEM REFER to
Section 501 - 14B .
B1312 Lamp Headlamp Input Circuit
Short to Battery GEM REFER to
Section 413 - 09 .
B1317 Battery Voltage High GEM REFER to
Section 414 - 00 .
B1318 Battery Voltage Low GEM REFER to
Section 414 - 00 .
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 .
B1339 Chime Input Request Circuit
Short to Battery GEM REFER to
Section 413 - 09 .
B1340 Chime Input Request Circuit
Short to Ground GEM REFER to
Section 413 - 09 .
B1342 ECU is Defective GEM Clear the DTCs. Retrieve the DTCs. If DTC B1342
is retrieved, INSTALL a new GEM. REFER to Section 419 - 10 .
B1353 Ignition Key-
In Circuit Open GEM REFER to
Section 413 - 09 .
B1359 Ignition Run/Acc Circuit Failure GEM REFER to
Section 211 - 05 .
B1396 Power Door Lock Circuit Short
to Battery GEM REFER to
Section 501 - 14B .
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 .
B1408 Driver Power Window Up
Circuit Short to Battery GEM REFER to
Section 501 - 11 .
B1426 Lamp Safety Belt Circuit Short
to Battery GEM Go To Pinpoint Test K .
B1428 Lamp Safety Belt Circuit Failure GEM Go To Pinpoint Test K .
B1431 Wiper Brake/Run Relay Circuit
Failure GEM REFER to
Section 501 - 16 .
B1432 Wiper Brake/Run Relay Circuit
Short to Battery GEM REFER to
Section 501 - 16 .
B1434 Wiper Hi/Low Speed Relay Coil
Circuit Failure GEM REFER to
Section 501 - 16 .
B1436 Wiper Hi/Low Speed Relay Coil
Circuit Short to Battery GEM REFER to
Section 501 - 16 .
B1438 Wiper Mode Select Switch
Circuit Failure GEM REFER to
Section 501 - 16 .
B1441 Wiper Mode Select Switch
Circuit Short to Ground GEM REFER to
Section 501 - 16 . Klj . 8 ba
412003 Mustang Workshop Manual
18. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_5108/S3B~us~en~ ...

Symptom Chart B1446 Wiper Park Sense Circuit
Failure GEM REFER to
Section 501 - 16 .
B1448 Wiper Park Sense Circuit Short
to Battery GEM REFER to
Section 501 - 16 .
B1450 Wiper Wash/Delay Switch
Circuit Failure GEM REFER to
Section 501 - 16 .
B1453 Wiper Wash/Delay Switch
Circuit Short to Ground GEM REFER to
Section 501 - 16 .
B1458 Wiper Washer Pump Motor
Relay Circuit Failure GEM REFER to
Section 501 - 16 .
B1460 Wiper Washer Pump Motor
Relay Coil Circuit Short to Battery GEM REFER to
Section 501 - 16 .
B1462 Safety Belt Switch Circuit
Failure GEM REFER to
Section 413 - 09 .
B1466 Wiper Hi/Low Speed Not
Switching GEM REFER to
Section 501 - 16 .
B1473 Wiper Low Speed Circuit Motor
Failure GEM REFER to
Section 501 - 16 .
B1476 Wiper High Speed Circuit Motor
Failure GEM REFER to
Section 501 - 16 .
B1551 Decklid Release Circuit Failure GEM REFER to
Section 501 - 14B .
B1553 Decklid Release Circuit Short to
Battery GEM REFER to
Section 501 - 14B .
B1555 Ignition Run/Start Circuit
Failure GEM REFER to
Section 211 - 05 .
B1687 Lamp Dome Input Circuit Short
to Battery GEM REFER to
Section 417 - 02 .
B2486 Parklamp Output Relay Driver
Circuit Failure GEM REFER to
Section 419 - 01 .
B2488 Parklamp Output Relay Driver
Short to Battery GEM REFER to
C1189 Brake Fluid Level Sensor Input
Short Circuit to Ground GEM Go To Pinpoint Test O .
C1223 Lamp Brake Warning Output
Circuit Failure GEM Go To Pinpoint Test O .
C1225 Lamp Brake Warning Output
Circuit Short to Battery GEM Go To Pinpoint Test O .
Symptom Chart Condition
Possible Sources Action
z No communication with
the generic electronic
module (GEM) z
Central junction
box (CJB) fuse
(s):
„7 (15A).
„ 39 (5A).
„ 43 z
Go To Pinpoint Test W Klj . 9 ba
412003 Mustang Workshop Manual
18. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_5108/S3B~us~en~ ...

z
Powertrain
control module
(PCM). manual.
z The CHECK FUEL CAP
INDICATOR is never on z
Circuitry.
z Standard
corporate
protocol (SCP)
network.
z Powertrain
control module
(PCM). z
Go To Pinpoint Test N .
z The CHECK FUEL CAP
INDICATOR is always
on z
Circuitry.
z Powertrain
control module
(PCM).
z Fuel system. z
REFER to the Powertrain
Control/Emissions
Diagnosis (PC/ED)
manual.
z The BRAKE warning
indicator is never/always
on z
Circuitry.
z Low brake fluid
level.
z Brake fluid
level switch.
z Parking brake
switch.
z Instrument
cluster.
z Generic
electronic
module (GEM). z
Go To Pinpoint Test O .
z The charging system
warning indicator is
never/always on z
Circuitry.
z Generator.
z Charging
system warning
indicator bulb.
z Instrument
cluster. z
Go To Pinpoint Test P .
z The high beam indicator
is never/always on z
Circuitry.
z High beam
indicator bulb.
z Instrument
cluster. z
Go To Pinpoint Test Q .
z The air bag warning
indicator is never/always
on z
Circuitry.
z Air bag warning
indicator bulb.
z Instrument
cluster.
z Restraint
control module
(RCM). z
REFER to Section 501 -
20B .
z The anti- lock brake
system (ABS) warning
indicator is never on z
Circuitry.
z ABS warning
indicator bulb.
z Anti- lock brake
control module.
z Instrument
cluster. z
Go To Pinpoint Test R .
z The ABS warning
indicator is always on z
Circuitry.
z Anti- lock brake
control module. z
REFER to Section 206 -
09A or
Section 206 - 09B . Klj . 12 ba
412003 Mustang Workshop Manual
18. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_5108/S3B~us~en~ ...

PINPOINT TEST O: THE BRAKE WARNING INDICATOR IS
NEVER/ALWAYS ON INDICATOR LAMP CONTROL III ACTIVE
COMMAND USING THE DIAGNOSTIC TOOL
z
Connect the diagnostic tool.
z Enter the following diagnostic mode on the
diagnostic tool: Instrument Cluster Active
Command.
z Select the instrument cluster INDICATOR
LAMP CONTROL III active command.
Trigger the CHECK FUEL CAP active
command ON. Observe the CHECK FUEL
CAP indicator.
z Does the CHECK FUEL CAP indicator
illuminate? Yes
REFER to the Powertrain
Control/Emissions Diagnosis (PC/ED)
manual.
No
GO to
N3 .
N3 CHECK FOR CORRECT INSTRUMENT
CLUSTER OPERATION z
Disconnect all instrument cluster connectors.
z Check for:
zcorrosion
z pushed- out pins
z Connect all instrument cluster connectors
and make sure they seat correctly.
z Operate the system and verify the concern is
still present.
z Is the concern still present? Yes
INSTALL a new instrument cluster. REFER
to
Instrument Cluster in this section. TEST
the system for normal operation.
No
The system is operating correctly at this
time. Concern may have been caused by a
loose or corroded connector. CLEAR the
DTCs. REPEAT the self- test. Test Step Result / Action to Take
O1 CHECK IF THE GEM IS RECEIVING THE CORRECT
IGNITION SWITCH STATUS CAUTION: Use the correct probe adapter(s) when
making measurements. Failure to use the correct probe
adapter(s) may damage the connector.
z Connect the diagnostic tool.
z Key in ON position.
z Enter the following diagnostic mode on the diagnostic tool:
Generic Electronic Module (GEM) PID.
z Monitor GEM PIDs IGN_KEY, IGN_S, IGN_R, and IGN_A
while cycling the ignition switch through all positions and
then removing the key from ignition switch.
z Do the PIDs agree with the ignition switch status? Yes
GO to
O2 .
No
REFER to Section 211 - 05 .
O2 DETERMINE IF GEM IS RECEIVING THE CORRECT
PARKING BRAKE INPUT z
Monitor GEM PID PRK_BRK while applying and releasing
the parking brake.
z Did the PID read ON with the parking brake applied, and
OFF with the parking brake released? Yes
GO to
O3 .
No
GO to O5 .
O3 DETERMINE IF BRAKE WARNING INDICATOR CIRCUIT IS
OPEN OR GROUNDED z
Verify that the parking brake is released.
z Is the instrument cluster BRAKE warning indicator off? Yes
GO to
O4 . Klj . 28 ba
412003 Mustang Workshop Manual
18. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_5108/S3B~us~en~ ...

No
GO to
O11 .
O4 DETERMINE IF GEM IS SENDING THE CORRECT OUTPUT
SIGNAL z
Trigger the GEM active command BKFLD LOW.
z Did the instrument cluster BRAKE warning indicator
illuminate? Yes
GO to
O14 .
No
GO to O9 .
O5 CHECK CIRCUIT BETWEEN THE PARKING BRAKE
SWITCH AND THE GEM FOR A SHORT TO GROUND z
Monitor PID PRK_BRK while applying and releasing the
parking brake.
z Did the PID read ON with the parking brake applied and
with the parking brake released? Yes
GO to
O8 .
No
GO to O6 .
O6 CHECK CIRCUIT 128 (VT/YE) AND CIRCUIT 22 (LB/BK)
FOR AN OPEN z
Key in OFF position.
z Disconnect: Parking Brake Switch C306.
z Disconnect: GEM C201d.
z Measure the resistance between the GEM C201d pin 4,
circuit 128 (VT/YE), harness side and the parking brake
switch C306 pin 1, circuit 22 (LB/BK), harness side.
z Is the resistance less than 5 ohms? Yes
GO to
O7 .
No
REPAIR the circuit. TEST
the system for normal
operation. O7 CHECK CIRCUIT 1205 (BK) FOR OPEN
z
Measure the resistance between the parking brake switch
C306 pin 2, circuit 1205 (BK), harness side and ground.
z Is the resistance less than 5 ohms? Yes
INSTALL a new parking
brake switch. TEST the
system for normal
operation.
No
REPAIR the circuit. TEST
the system for normal
operation.
O8 CHECK CIRCUIT 128 (VT/YE) FOR A SHORT TO GROUND
z
Key in OFF position.
z Disconnect: Parking Brake Switch C306.
z Disconnect: GEM C201d.
z Measure the resistance between the GEM C201d pin 4,
circuit 128 (VT/YE), harness side and ground. Yes
REPAIR or INSTALL a new
parking brake switch as
needed. TEST the system
for normal operation. Klj . 29 ba
412003 Mustang Workshop Manual
18. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_5108/S3B~us~en~ ...

z
Is the resistance greater than 10,000 ohms? No
REPAIR the circuit. TEST
the system for normal
operation.
O9 CHECK CIRCUIT 128 (VT/YE) FOR SHORT TO BATTERY
z
Key in OFF position.
z Disconnect: GEM C201e.
z Disconnect: Instrument Cluster C220b.
z Key in ON position.
z Measure the voltage between the GEM C201e pin 13, circuit
128 (VT/YE), harness side and ground.
z Is any voltage indicated? Yes
REPAIR the circuit. TEST
the system for normal
operation.
No
GO to
O10 .
O10 CHECK CIRCUIT 128 (VT/YE) FOR AN OPEN
z
Key in OFF position.
z Measure the resistance between the GEM C201e pin 13,
circuit 128 (VT/YE), harness side and the instrument cluster
C220b pin 14, circuit 128 (VT/YE), harness side.
z Is the resistance less than 5 ohms? Yes
GO to
O15 .
No
REPAIR the circuit. TEST
the system for normal
operation. O11 CHECK THE BRAKE FLUID LEVEL SWITCH FOR AN
INTERNAL GROUND z
Key in OFF position.
z Disconnect: Brake Fluid Level Switch C124.
z Key in ON position.
z With the parking brake released, observe the BRAKE
warning indicator.
z Is the BRAKE warning indicator always on? Yes
GO to
O12 .
No
INSTALL a new brake fluid
level switch. TEST the
system for normal
operation. Klj . 30 ba
412003 Mustang Workshop Manual
18. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_5108/S3B~us~en~ ...