2003 FORD MUSTANG torque

DESCRIPTION AND OPERATION
Geartrain
Power is transmitted from the torque converter to the Ravigneaux geartrain components through the
input shaft and forward clutch cylinder.
zThe geartrain contains a Ravigneaux planetary set connected by dual pinion gears.
z By holding or driving certain components of the gearset, four forward ratios and one reverse
ratio are obtained and transmitted to the output shaft. The ratios are as follows:
z Components of the geartrain can be held by bands or clutches and driven by clutches only.
The 4R70W uses:
ztwo bands.
z two one- way clutches (one roller, one mechanical diode).
z four friction clutches.
Planetary Gearset
The planetary gearset in the transmission is a Ravigneaux- type set consisting of the following
components:
zforward clutch sun gear
z reverse clutch sun gear
z a pinion carrier
z long and short pinions
z output ring gear
Components are held or driven to produce forward and reverse gear ratios.
Input Shaft
The forward clutch cylinder and shaft transfers speed and torque from the converter turbine to the
geartrain. This shaft is splined to the turbine on one end and to the forward clutch sun gear and stub
shaft on the other end. SECTION 307-
01: Automatic Transaxle/Transmission 2003 Mustang Workshop Manual Gear Ratio
1st 2.84 to 1
2nd 1.55 to 1
3rd 1.00 to 1
4th 0.70 to 1
Reverse 2.32 to 1 Klj . 1 ba
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Stub Shaft
The stub shaft transfers power from the input shaft to the planet carrier (through the direct clutch)
during third and fourth gear operation.
Output Shaft
The output shaft provides torque to the driveshaft and rear axle assembly. It is driven by the ring gear
of the planetary gearset. Klj . 2 ba
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The transmission uses a gerotor-
type design front pump support and gear. The pump provides the
volume of fluid needed to charge the torque converter, main control assembly, cooling system and
lube system. Pump pressure is regulated by the main regulator valve. The pump has an internal boost
circuit which is more efficient at lower engine speeds.
Filter
All fluid drawn from the transmission pan by the pump passes through the filter. The filter and its
accompanying seal are part of the fluid path from the sump (pan) to the fluid pump.
Main Control
The main control valve body houses three electronic solenoids:
ztwo shift solenoids
z one torque converter clutch solenoid (TCC solenoid) Accumulators 1 — Outer rotor (part of 7A103)
2 — Inner rotor (part of 7A103)
3 — Outlet
4 — Inlet
Item Part Number Description
1 — Shift solenoid A (part of 7G484)
2 7G136 Torque converter clutch solenoid
3 — Shift solenoid B (part of 7G484) Klj . 2 ba
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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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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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DIAGNOSIS AND TESTING
Preliminary Inspection
The following items must be checked prior to beginning the diagnostic procedures:
Know and Understand the Concern
In order to correctly diagnose a concern, first understand the customer complaint or condition.
Customer contact may be required in order to begin to verify the concern. Understand the conditions,
including when the concern occurs. For example:
zHot or cold vehicle temperature
z Hot or cold ambient temperature
z Vehicle driving conditions
z Vehicle loaded/unloaded
After understanding when and how the concern occurs, proceed to Verification of Condition.
Verification of Condition
This section provides information that must be used in both determining the actual cause of customer
concerns and carrying out the appropriate procedures.
The following procedures must be used when verifying customer concerns for the transmission.
Determine Customer Concern
NOTE: Some transmission conditions can cause engine concerns. An electronic pressure control short
circuit can cause engine misfiring. The torque converter clutch not disengaging will stall the engine.
Determine customer concerns relative to vehicle use and dependent driving conditions, paying
attention to the following items:
zHot or cold vehicle operating temperature
z Hot or cold ambient temperatures
z Type of terrain
z Vehicle loaded/unloaded
z City/highway driving
z Upshifting
z Downshift
z Coasting
z Engagement
z Noise/vibration — check for dependencies, either rpm dependent, vehicle speed dependent,
shift dependent, gear dependent, range dependent, or temperature dependent.
Check Fluid Level and Condition
Fluid Level Check SECTION 307-
01: Automatic Transaxle/Transmission 2003 Mustang Workshop Manual Klj . 1 ba
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CAUTION: The use of any other type of transmission fluid than specified could result in
transmission failure.
If fluid needs to be added, add fluid in 0.25L (1/2 pint) increments through the filler tube. Do not overfill
the fluid. For fluid type, refer to the specification chart.
Fluid Condition Check
1. Check the fluid level.
2. Observe the color and the odor. The color under normal circumstances should be dark reddish, not brown or black or have a burnt odor.
3. Hold the fluid level indicator over a white facial tissue and allow the fluid to drip onto the facial tissue and examine the stain.
4. If evidence of solid material is found, the transmission fluid pan should be removed for further inspection.
5. If the stain is a foamy pink color this may indicate coolant in the transmission. The engine cooling system should also be inspected at this time.
6. If fluid contamination or transmission failure is confirmed by the sediment in the bottom of the fluid pan, the transmission must be disassembled and completely cleaned. This includes the
torque converter and cooler tubes. The oil- to-air cooler will need to be installed.
7. Carry out diagnostic checks and adjustments. Refer to Diagnosis By Symptom in this section. Klj . 3 ba
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DIAGNOSIS AND TESTING
Road Testing Vehicle
NOTE:
Always drive the vehicle in a safe manner according to the driving conditions and obey all
traffic laws.
The shift point road test and torque converter operation tests provide diagnostic information on
transmission shift controls and torque converter operation. SECTION 307-
01: Automatic Transaxle/Transmission 2003 Mustang Workshop Manual Klj . 1 ba
12003 Mustang Workshop Manual
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