automatic transmission FORD MUSTANG 2003 Service Manual

DESCRIPTION AND OPERATION
Torque Converter
The torque converter transmits and multiplies torque. The torque converter is a four-
element device:
z impeller assembly
z turbine assembly
z reactor assembly
z clutch and damper assembly
The standard torque converter components operate as follows:
zRotation of the converter housing and impeller set the fluid in motion.
z The turbine reacts to the fluid motion from the impeller, transferring rotation to the geartrain
through the input shaft.
z The reactor redirects fluid going back into the impeller, allowing for torque multiplication.
z The clutch and damper assembly dampens powertrain torsional vibration and provides a direct
mechanical connection for improved efficiency.
z Power is transmitted from the torque converter to the planetary gearsets and other components
through the input shaft.
SECTION 307-
01: Automatic Transaxle/Transmission 2003 Mustang Workshop Manual Item Part Number Description
1 — Converter clutch and damper (part of 7902)
2 — Reactor (part of 7902)
3 — Turbine (part of 7902) Klj . 1 ba
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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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DESCRIPTION AND OPERATION
Apply Components
There are eight apply components used to drive or hold the planetary gearset components.
Band—
Overdrive
The overdrive band holds the reverse clutch drum stationary in fourth gear and manual 2. This action
causes the reverse sun gear to be held in these ranges.
Band— Low and Reverse
The low and reverse band holds the pinion carrier in reverse. The reverse band also applies in manual
1 position to provide engine braking.
Clutch— Intermediate Intermediate Clutch Disassembled View SECTION 307-
01: Automatic Transaxle/Transmission 2003 Mustang Workshop Manual Item Part Number Description
1 7F196 Overdrive band assembly
2 7D044 Reverse clutch drum assembly
Item Part Number Description
1 7A398 Planetary assembly
2 7D095 Reverse band assembly Klj . 1 ba
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DESCRIPTION AND OPERATION
Hydraulic System
Fluid Pump
SECTION 307-
01: Automatic Transaxle/Transmission 2003 Mustang Workshop Manual Item Part Number Description
1 7A106 Front pump body assembly
2 7005 Case assembly
3 7A194 Transmission pan
4 7A191 Transmission pan gasket
5 7A098 Fluid filter and seal assembly
6 7A100 Main control assembly
7 7A108 Front pump support assembly
8 7D273 Fluid tube connector assembly (2 req'd)
Item Part Number Description Klj . 1 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.
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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
Diagnostic Strategy
Troubleshooting an electronically controlled automatic transmission is simplified by using the proven
method of diagnosis. One of the most important things to remember is that there is a definite
procedure to follow.
NOTE:
Do not take any short cuts or assume that critical checks or adjustments have already been
made.
Follow the procedures as written to avoid missing critical components or steps.
To properly diagnose a concern have the following publications available:
zTransmission Reference Manual.
z Powertrain Control/Emissions Diagnosis (PC/ED) manual.
z TSBs and OASIS Messages.
z Wiring Diagram.
These publications provide the information required when diagnosing transmission concerns.
Use the Diagnostic Flow Chart as a guide and follow the steps as indicated.
Preliminary Inspection
zKnow and understand the customer's concern.
z Verify the concern by operating the vehicle.
z Check the fluid levels and condition.
z Check for non-factory add- on items.
z Check shift linkages for proper adjustment.
z Check TSBs and OASIS messages regarding the concern.
Diagnostics
zCarry out on- board diagnostic procedures key on engine off (KOEO) and key on engine running
(KOER).
z Record all diagnostic trouble codes (DTCs).
z Repair all non- transmission codes first.
z Repair all transmission codes second.
z Erase all continuous codes and attempt to repeat them.
z Repair all continuous codes.
z If only pass codes are obtained, refer to Diagnosis By Symptom for further information and
diagnosis.
Follow the diagnostic sequence to diagnose and repair the concern the first time. SECTION 307-
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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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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-
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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-
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