2003 FORD MUSTANG Workshop Manual

ESP trailer tire pressure fuel consumption fuses airbag

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FORD MUSTANG 2003 Workshop Manual DESCRIPTION AND OPERATION
Transmission Electronic Control System
The powertrain control module (PCM) and its input/output network control the following transmission
operations:
�zShift timing
�z

DESCRIPTION AND OPERATION
Transmission Electronic Control System
The powertrain control module (PCM) and its input/output network control the following transmission
operations:
zShift timing
z Line pressure (shift feel)
z Torque converter clutch
The transmission control is separate from the engine control strategy in the PCM, although some of
the input signals are shared. When determining the best operating strategy for transmission operation,
the PCM uses input information from certain engine- related and driver-demand related sensors and
switches.
In addition, the PCM receives input signals from certain transmission- related sensors and switches.
The PCM also uses these signals when determining transmission operating strategy.
Using all of these input signals, the PCM can determine when the time and conditions are right for a
shift, or when to apply or release the torque converter clutch (TCC). It will also determine the best line
pressure needed to optimize shift feel. To accomplish this, the PCM uses hydraulic solenoids to control
transmission operation.
The following provides a brief description of each of the sensors and actuators used to control
transmission operation.
Powertrain Control Module (PCM)
The operation of the transmission is controlled by the powertrain control module (PCM). Many input
sensors provide information to the PCM. The PCM then controls actuators which determine
transmission operation.
Air Conditioning (A/C) Clutch
An electromagnetic clutch is energized when the clutch cycling pressure switch closes. The switch is
located on the suction accumulator/drier. The closing of the switch completes the circuit to the clutch
and draws it into engagement with the compressor driveshaft. When the A/C clutch is engaged,
electronic pressure control (EPC) is adjusted by the PCM to compensate for additional load on the
engine.
Brake Pedal Position (BPP) Switch
The brake pedal position (BPP) switch tells the PCM when the brakes are applied. The torque
converter clutch disengages when the brakes are applied. The BPP switch closes when the brakes are
applied and opens when they are released.
Engine Coolant Temperature (ECT) Sensor
The engine coolant temperature (ECT) sensor detects temperature of engine coolant and supplies the
information to the powertrain control module. The ECT sensor is used to control torque converter
clutch (TCC) operation. The ECT is installed in the heater outlet fitting or cooling passage on the
engine. For engine control applications, the ECT signal is used to modify ignition timing, EGR flow and
air- to-fuel ratio as a function of engine coolant temperature.
SECTION 307-
01: Automatic Transaxle/Transmission 2003 Mustang Workshop Manual Klj . 1 ba
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FORD MUSTANG 2003 Workshop Manual Ignition Coil —
Coil On Plug
The engine uses eight separate coil per plug units. Each coil per plug unit is controlled by the
powertrain control module (PCM).
Each coil per plug unit is mounted d

Ignition Coil —
Coil On Plug
The engine uses eight separate coil per plug units. Each coil per plug unit is controlled by the
powertrain control module (PCM).
Each coil per plug unit is mounted directly above each spark plug and activates its own spark plug in
the correct sequence as controlled by the PCM.
Refer to the Powertrain Control/Emissions Diagnosis (PC/ED) manual for additional information on the
ignition system.
Intake Air Temperature (IAT) Sensor
The intake air temperature (IAT) sensor provides the sequential fuel injection (SFI) system mixture
temperature information. The IAT sensor is used both as a density corrector for air flow calculation and
to proportion cold enrichment fuel flow. The IAT sensor is installed in the air cleaner inlet tube. The IAT
sensor is also used in determining EPC pressures.
Mass Air Flow (MAF) Sensor
The mass air flow (MAF) sensor measures the mass of air flowing into the engine. The MAF sensor
output signal is used by the powertrain control module to calculate injector pulse width. For
transmission strategies, the mass air flow sensor is used to regulate EPC, shift and torque converter
clutch scheduling.
Transmission Control Switch (TCS) and Transmission Control Indicator Lamp (TCIL)
The transmission control switch (TCS) is a momentary contact switch. When the switch is pressed, a
signal is sent to the PCM to allow automatic shifts from first through fourth gears or first through third
gears only. The PCM energizes the transmission control indicator lamp (TCIL) when the switch is off.
The TCIL indicates overdrive cancel mode activated (lamp on). When the TCIL is flashing, it indicates
electronic pressure control (EPC) circuit shorted or a monitored sensor failure.
Throttle Position (TP) Sensor
The throttle position (TP) sensor is a potentiometer mounted on the throttle body. The TP sensor
detects the position of the throttle plate and sends this information to the PCM. The TP sensor is used
for shift scheduling, electronic pressure control (EPC) and TCC control.
Digital Transmission Range (TR) Sensor
The digital transmission range (TR) sensor is located on the outside of the transmission at the manual
lever. The digital sensor completes the start circuit in PARK and NEUTRAL, and the back- up lamp
circuit in REVERSE. The digital sensor also opens/closes a set of four switches that are monitored by
the PCM to determine the position of the manual lever (P, R, N, D, 2, 1).
Output Shaft Speed (OSS) Sensor
The output shaft speed (OSS) sensor is a magnetic pickup, located at the output shaft ring gear, that
sends a signal to the powertrain control module (PCM) to indicate transmission output shaft speed.
The OSS sensor is used for torque converter clutch (TCC) control, shift scheduling and to determine
electronic pressure control (EPC).
Electronic Pressure Control (EPC) Solenoid
The EPC solenoid regulates transmission pressure. EPC valve pressure is used to control line
pressure.
Torque Converter Clutch (TCC) Solenoid Klj . 2 ba
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FORD MUSTANG 2003 Workshop Manual The TCC solenoid is used to control the apply and release of the TCC.
Shift Solenoid —
SSA, SSB
Two on/off shift solenoids provide gear selection of first through fourth gears by controlling the

The TCC solenoid is used to control the apply and release of the TCC.
Shift Solenoid —
SSA, SSB
Two on/off shift solenoids provide gear selection of first through fourth gears by controlling the
pressure to the three shift valves. One unit containing the two shift solenoids is located in the main
control valve body. The shift solenoids are two- way, normally open style.
a When a manual pull- in occurs above a calibrated speed, the transmission will not downshift from the
higher gear until the vehicle speed drops below this calibrated speed.
EC = Electronically Controlled
HD = Hydraulically Disabled
Transmission Fluid Temperature (TFT) Sensor
The transmission fluid temperature (TFT) sensor is located on the lead frame assembly near the shift
solenoids on the main control valve body. It is a temperature- sensitive device called a thermistor. It
sends a voltage signal to the PCM. The voltage signal varies with transmission fluid temperature. The
PCM uses this signal to determine whether a cold start shift schedule is necessary. The shift schedule
is compensated when the transmission fluid temperature is cold. The PCM also inhibits (TCC)
operation at low transmission fluid temperatures and corrects electronic pressure control.
Vehicle Speed (VSS) Sensor
The source of vehicle speed (VSS) is model dependent. Possible sources of vehicle speed input are
anti- lock brake sensor (ABS), a gear- driven vehicle speed sensor (VSS), or an output shaft speed
sensor (OSS). The VSS signal is either an A/C signal whose frequency changes with speed, or an
SCP data message depending on the source. Some applications will have both. The vehicle speed
signal is an input to various vehicle subsystems such as the powertrain control module (PCM),
instrument cluster (speedometer and odometer), speed control system, etc. The vehicle speed source
must be operational to enter output state control (OSC) mode for diagnostics.
Regardless of the type of vehicle speed system, the PCM always uses the OSS for transmission and Solenoid Operation Chart Selector Lever Position PCM Commanded Gear Solenoids
SSA SSB TCC
P/R/N 1 ON OFF HD
(D) 1 ON OFF HD
(D) 2 OFF OFF EC
(D) 3 OFF ON EC
(D) 4 ON ON EC
w/OD OFF
1 1 ON OFF HD
2 2 OFF OFF EC
3 3 OFF ON EC
Manual 2 2 OFF OFF EC
Manual 1 1 ON OFF HD
1
a 2 OFF OFF EC Klj . 3 ba
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FORD MUSTANG 2003 Workshop Manual engine control. Klj . 4 ba
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FORD MUSTANG 2003 Workshop Manual DIAGNOSIS AND TESTING
Diagnostic Strategy
Troubleshooting an electronically controlled automatic transmission is simplified by using the proven
method of diagnosis. One of the most important things

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FORD MUSTANG 2003 Workshop Manual Klj . 2 ba
22003 Mustang Workshop Manual
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FORD MUSTANG 2003 Workshop Manual DIAGNOSIS AND TESTING
Diagnostic Flow Chart
SECTION 307-
01: Automatic Transaxle/Transmission 2003 Mustang Workshop Manual Diagnostic Flow Chart
�z
Know and understand
the customer concerns
�z

DIAGNOSIS AND TESTING
Diagnostic Flow Chart
SECTION 307-
01: Automatic Transaxle/Transmission 2003 Mustang Workshop Manual Diagnostic Flow Chart
z
Know and understand
the customer concerns
z Check the fluid level
and condition
z Verify the concern by
operating the vehicle
z Check for non- factory-
installed items and
verify correct installation
z Check the shift linkage
adjustments
z Check TSBs and
OASIS messages for
vehicle concerns
z Carry out quick test
both KOER and KOEO
z Record all codes
1) Did you record any
diagnostic trouble codes? Yes ·
REPAIR all hard diagnostic trouble codes. FOLLOW the
pinpoint tests. REFER to the Powertrain Control/Emissions
Diagnosis (PC/ED) manual first, then this Workshop Manual. No ·
REFER to Diagnosis By Symptom in this section, then GO to
Step 5. 2) Are any continuous test
memory codes present? Yes ·
CLEAR codes and CARRY OUT drive cycle test. No ·
GO to Step 4. 3) Did the continuous test
memory codes reappear? Yes ·
REPAIR all continuous test memory codes. FOLLOW the
pinpoint tests. REFER to the Powertrain Control/Emissions
Diagnosis (PC/ED) manual then the transmission reference
manual, then this workshop manual, then GO to Step 4. No ·
GO to Step 4. 4) Is the concern repaired? Yes ·
CARRY OUT the final quick test to verify that no diagnostic
trouble codes are present. CLEAR memory codes. No ·
REFER to Diagnosis By Symptom in this section.
5) Are there any electrical
concerns? Yes ·
INSTALL the scan tool and CARRY OUT the output state
control test, then GO to Step 6. No ·
REFER to the hydraulic and mechanical routine to diagnose
and REPAIR the concern, then GO to Step 7. 6) Was the transmission
concern corrected when the
scan tool was installed? Yes ·
REFER to the Powertrain Control/Emissions Diagnosis
(PC/ED) manual, intermittent fault diagnosis section and use
the scan tool to diagnose cause of concern in the processor,
vehicle harness or external inputs (sensors or switches). Klj . 1 ba
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FORD MUSTANG 2003 Workshop Manual No ·
REFER to the hydraulic and mechanical routine to diagnose
the concern, then GO to Step 7. 7) Is the concern repaired? Yes ·
CARRY OUT the final quick test to verify that no diagnostic

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