2003 FORD MUSTANG fuel cap

DESCRIPTION AND OPERATION
Instrument Cluster
The instrument cluster (10849) consists of the following components:
Instrument Cluster—
Base 3.8L Engine
SECTION 413-
01: Instrument Cluster 2003 Mustang Workshop Manual Item Part
Number Description
1 — Fuel gauge
2 — Engine coolant temperature gauge
3 — Speedometer
4 — Turn signal/hazard indicator
5 — High beam indicator
6 — Tachometer
7 — Odometer
8 — Trip odometer reset button
9 — Voltmeter gauge
10 — Oil pressure gauge
11 — CHECK FUEL CAP indicator
12 — BRAKE warning indicator
13 — ABS warning indicator
14 — Traction control indicator
15 — Overdrive off (O/D OFF) indicator (automatic Klj . 1 ba
42003 Mustang Workshop Manual
18. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_5108/S3B~us~en~ ...

Instrument Cluster—
Base 4.6L Engine transmission)
16 — LOW FUEL level indicator
17 — SERVICE ENGINE SOON indicator
18 — THEFT indicator
19 — AIR BAG warning indicator
20 — Charging system indicator
21 — Safety belt warning indicator
Item Part
Number Description
1 — Fuel gauge
2 — Engine coolant temperature gauge
3 — Speedometer
4 — Turn signal/hazard indicator
5 — High beam indicator
6 — Tachometer
7 — Odometer
8 — Trip odometer reset button
9 — Voltmeter gauge
10 — Oil pressure gauge
11 — CHECK FUEL CAP indicator
12 — BRAKE warning indicator
13 — ABS warning indicator Klj . 2 ba
42003 Mustang Workshop Manual
18. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_5108/S3B~us~en~ ...

Instrument Cluster—
Cobra 14 — Traction control indicator
15 — Overdrive off (O/D OFF) indicator (automatic
transmission)
16 — LOW FUEL level indicator
17 — SERVICE ENGINE SOON indicator
18 — THEFT indicator
19 — AIR BAG warning indicator
20 — Charging system indicator
21 — Safety belt warning indicator
Item Part
Number Description
1 — Fuel gauge
2 — Engine coolant temperature gauge
3 — Speedometer
4 — Turn signal/hazard indicator
5 — High beam indicator
6 — Tachometer
7 — Odometer
8 — Trip odometer reset button
9 — Boost gauge
10 — Oil pressure gauge
11 — CHECK FUEL CAP indicator
12 — BRAKE warning indicator Klj . 3 ba
42003 Mustang Workshop Manual
18. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_5108/S3B~us~en~ ...

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~ ...

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 N: THE CHECK FUEL CAP INDICATOR IS NEVER
ON Test Step Result / Action to Take
M1 CHECK THE O/D OFF
INDICATOR OPERATION z
Key in ON position.
z Observe the O/D OFF indicator.
z Is the O/D OFF indicator
always on? Yes
GO to
M2 .
No
GO to M3 .
M2 CHECK THE INSTRUMENT
CLUSTER z
Key in OFF position.
z Disconnect: Instrument Cluster
C220a.
z Key in ON position.
z Observe the O/D OFF indicator.
z Did the indicator turn off? Yes
REFER to the Powertrain Control/Emissions Diagnosis
(PC/ED) manual.
No
GO to
M4 .
M3 CHECK THE INSTRUMENT
CLUSTER OPERATION z
Carry out the instrument cluster
self- diagnostic mode.
z Did the O/D OFF indicator
illuminate? Yes
REFER to the Powertrain Control/Emissions Diagnosis
(PC/ED) manual.
No
GO to
M4 .
M4 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
N1 RETREIVE AND RECORD DTCS FROM
CONTINUOUS AND ON- DEMAND SELF-TESTS—
PCM NOTE:
Once the check fuel cap indicator
does turn on, it does not turn off unless the
fuel cap has been correctly secured and the
vehicle has been driven for several minutes.
z Use recorded PCM DTCs from the
continuous and on- demand self-test.
z Are any DTCs recorded? Yes
If PCM DTC P0457, REFER to the
Powertrain Control/Emissions Diagnosis
(PC/ED) manual.
No
GO to
N2 .
N2 CARRY OUT THE INSTRUMENT CLUSTER Klj . 27 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~ ...