Ford Workshop Service and Repair Manuals

View of the automatic transmission

The automatic transmission consists of a four-part torque converter with lock-up clutch as well as the following components:

• Planetary gearset
• Chain drive
• Planetary gearset final drive
• Differential pinion and side gears

The hydraulic control system of the CD4E has five solenoids that control:

• Gearshift pressure (through line pressure control)
• Gearshift control (through shift valve position control)
• Modulated actuation of the torque converter clutch
• Control of 3-2 shifts
• Engine braking during coast operation

Transaxle Identification Tag - Vehicles built up to 08/2003

Transaxle Identification Tag - Vehicles built 08/2003 onwards

Torque converter, converter housing, clutches

Oil pump, sensors, clutches

Selector lever, transmission range (TR) switch

Main control valve body assembly - Vehicles built up to 08/2003

Main control valve body assembly - Vehicles built 08/2003 onwards

Thrust bearings, thrust washers

Bushes

Transaxle Range Selection

The selector lever has six settings: P, R, N, D, 2, 1. A transmission control switch allows the driver to prevent a shift into fourth gear (overdrive). The engine braking effect can be used in second and third gear.

"P" PARK

In the PARK position, no powerflow is transferred through the transaxle. A shift lever connected to a set of cams presses the parking pawl into the park gear on the driven sprocket. This locks the final drive and prevents the vehicle from rolling. For safety reasons, always apply the parking brake whenever the vehicle is parked.

"R" REVERSE

REVERSE allows the vehicle to be operated in a rearward direction, at a reduced gear ratio. Engine braking is provided in REVERSE.

"N" NEUTRAL

As in PARK, there is no power transferred through the transaxle in NEUTRAL. However, the final drive is not locked by the parking pawl, so the wheels are free to rotate. The vehicle may be started in NEUTRAL.

"D" DRIVE

The DRIVE position provides all automatic shifts (first through fourth), the engagement and disengagement of the torque converter clutch and optimum fuel economy during normal operation. Engine braking is provided in the fourth gear. Fourth gear (overdrive) may be disabled by actuating the transmission control switch located on the transmission range selector. Engine braking is available in second and third gear if the transmission control switch is switched on (O/D deactivated, TCIL display on).

(2) "2"

In position "2", second gear remains engaged if the transmission is shifted manually or automatically up or down. If position "2" is selected while the vehicle is stationary, the vehicle will pull away in second gear to provide maximum traction on slippery surfaces. In position "2" engine braking is available in second gear.

(1) "1"

In position "1", first gear remains engaged if the transmission is downshifted manually or automatically. The transaxle is prevented from down shifting into first gear above a specific speed - approximately 48 km/h (30 mph) - to protect the powertrain from over-speeding. Engine braking is also available in position "1", which can be particularly useful on steep descents.

Transaxle Shift Patterns

Upshifts

The powertrain control module (PCM) controls transmission upshifts. The PCM receives signals from various sensors and inputs from the driver which it uses to control gearshifts, gearshift pressure and actuation of the lock-up clutch

Downshifts

Under certain conditions the transaxle will downshift automatically to a lower gear range (without moving the transaxle range selector lever). There are three categories of automatic downshifts: coastdown, torque demand, and forced or kickdown shifts.

Coastdown

The coastdown downshift occurs when the vehicle is coasting down to a halt.

Torque Demand

The torque demand downshift occurs automatically during part throttle acceleration when the demand for torque is greater than the engine can provide at that gear ratio. The engaged torque converter clutch will be disengaged to provide additional acceleration, if required.

Kickdown

Maximum acceleration is achieved when the driver forces a downshift by flooring the accelerator pedal. Forced kickdown into second gear is only possible below 88 km/h. At speeds less than 40 km/h kickdown causes the transmission to downshift into first gear. These specifications are subject to modification due to changes in tire size and engine settings.

Transmission Control Switch and Lamp Operation

Overdrive (O/D) may be cancelled by actuating the transmission control switch in the transaxle range selector lever. The system automatically engages the O/D mode if the ignition switch is turned to RUN. O/D mode is disabled if the transmission control switch is operated with the ignition switch turned to RUN. Pressing the transmission control switch again reverts to the O/D mode. The transmission control indicator lamp switches alternately on and off when the transmission control switch is cycled.

Torque Converter Main Components and Functions - 261 mm (10.25 inch)

The CD4E torque converter is a four-element assembly. The torque converter contains an impeller, a turbine, a stator and a torque converter lock-up clutch to reduce fuel consumption. It couples the engine to the turbine shaft assembly, provides torque multiplication and absorbs engine shock of gear shifting.

Impeller and Cover

The impeller and cover assembly drives the impeller blades and pump assembly. The impeller is primarily responsible for driving the turbine with hydraulic fluid by means of centrifugal force. The cover provides a mating surface for the torque converter clutch piston plate and damper.

Turbine

The impeller drives the turbine with hydraulic fluid by means of centrifugal force. The turbine transmits the input torque via the turbine shaft to the drive chain and the driven sprocket.

Stator

The stator directs the flow of fluid back from the turbine to the impeller so that the fluid rotates in the same direction as the impeller. This process also serves to multiply torque.

Torque Converter Clutch (TCC)

The torque converter clutch (TCC) provides a mechanical link or direct drive between the engine crankshaft and the turbine shaft when it is engaged. The application of the torque converter clutch is controlled by the powertrain control module (PCM). Under certain conditions the PCM sends the corresponding signal to the TCC solenoid valve. As a result, the pressure of the fluid in the torque converter forces the piston plate and damper against the cover and creates a mechanical link between the engine and the transmission.

Geartrain

The geartrain includes the planetary gearsets, the actuating components and the final drive gearset and differential.

Planetary Gearsets

The CD4E transmission has two planetary gearsets for reverse drive and the four forward gears. The planetary gearsets consist of the following components:

• Low-intermediate sun gear assembly
• Low-intermediate planet carrier
• Low-intermediate ring gear assembly
• Reverse/overdrive sun gear and shell assembly
• Reverse/overdrive planet carrier assembly
• Reverse/overdrive ring gear assembly

Planetary Gearsets

Turbine Shaft

The turbine shaft connects the torque converter stator with the forward/coast/direct clutch cylinder. When engaged, the forward/coast/direct clutch cylinder transmits the input torque to the reverse/overdrive ring gear, which also acts as a drive sprocket. This allows input torque to be transmitted from the torque converter to the drive chain and driven sprocket.

Drive chain

Drive Chain and Sprockets

A drive chain transfers the torque from the turbine to the planetary gearsets. The drive chain consists of the following components:

• Reverse/overdrive ring gear assembly which also acts as a drive sprocket,
• Driven sprocket
• Drive chain

The drive chain connects the reverse/overdrive sun gear with the driven sprocket. The final drive sun gear located on top of the driven sprocket meshes with the final drive gearset.

Final Drive Gearset

The final drive consists of a planetary gearset that transfers and multiplies torque from the planetary gearsets to the differential. The final drive consists of the following components:

• Final drive sun gear: is chain driven by the reverse/overdrive ring gear assembly and transfers torque to the final drive carrier.
• Final drive carrier: the final drive carrier acts as the driven member and is part of the differential case.
• Final drive ring gear: is located in the converter housing and is always the held member of the final drive planetary gearset.

Differential Assembly

The differential assembly drives the differential pinion gears and the differential side gears which in turn drive the front wheel driveshaft and joints. It provides differential action if the driving wheels are turning at different speeds. The differential assembly consists of the following components:

• Differential case (part of the final drive carrier)
• Two pinion gears supported by a pinion shaft
• Two side gears supported by the differential case and halfshafts

Apply Components:

Band - intermediate and overdrive

The intermediate and overdrive brake band assembly holds the reverse clutch drum assembly to the transaxle case in second and fourth gear. This action causes the reverse/overdrive sun gear and shell assembly to be held stationary in second and fourth gears.

Intermediate and Overdrive Servo

The intermediate and overdrive servo is the hydraulic actuator for the intermediate and overdrive band assembly. Line pressure is applied through the servo apply circuit where it works on one side of the servo piston. This forces the piston to move up the servo bore in the transaxle case, which moves the servo apply rod against one side of the intermediate and overdrive band assembly. Because the other side of the intermediate and overdrive band assembly is anchored to the transaxle case, the sides of the intermediate and overdrive band assembly are squeezed around the reverse clutch drum assembly, holding the reverse clutch drum assembly stationary.

Clutch - Forward

The forward clutch connects the turbine shaft to the outer race of the forward one-way clutch which in turn drives the low/intermediate sun gear in all forward gear ranges. However, in fourth gear, the forward clutch transmits no power because the forward one-way clutch is overrunning. The forward clutch is a multi-disc clutch and is contained in the forward/coast/direct clutch cylinder assembly.

Clutch - Direct

The direct clutch connects the turbine shaft to the low/intermediate ring gear assembly when the vehicle is in third and fourth gears. It is a multi-disc clutch and is contained in the forward/coast/direct clutch cylinder assembly.

Clutch - Reverse

The reverse clutch connects the turbine shaft to the reverse/overdrive sun gear and shell assembly when the vehicle is in reverse gear. It is a multi-disc clutch and is contained in the reverse clutch drum assembly.

Clutch - Coast

The coast clutch is a multi-disc clutch located beneath the forward clutch in the forward/coast/direct clutch cylinder assembly. It connects the low/intermediate sun gear assembly to the turbine shaft assembly when the transmission control switch is on and in the DRIVE position or when a gear has been selected manually.

Clutch - Low/Reverse

The low/reverse clutch holds the reverse/overdrive carrier assembly to the transaxle case when the transaxle is shifted into the R and 1 positions. The low/reverse clutch is a multi-disc clutch. It is splined to the transaxle case.

Clutch - Forward One-Way

The forward one-way clutch is a sprag-type, one-way clutch. The forward one-way clutch combines with the forward clutch to connect the turbine shaft assembly to the low/intermediate sun gear assembly in first, second and third gears. The forward one-way clutch always overruns in all coasting operations and in fourth gear.

Clutch - Low One-Way

The low one-way clutch is a roller type one-way clutch which enables the transaxle case to hold the reverse/overdrive carrier stationary when the transaxle is in first gear. The low one-way clutch holds the reverse/overdrive carrier assembly during acceleration. When coasting, the low one-way clutch will overrun, disconnecting the final drive from the planetary gearset.

Hydraulic System

The hydraulic system uses transmission fluid to cool, to lubricate, and to provide hydraulic pressure to the hydraulic circuits within the transaxle.

Pump Assembly

Pump

The pump provides the volume of liquid required to charge the torque converter, main control valve body, cooling system, lubrication system and hydraulic actuating components. The transaxle uses a positive displacement gear and crescent-type pump which is shaft-driven by the torque converter.

Fluid Level and Filter

Fluid from the oil pan area (formed by the transaxle case and converter housing) flows through a filter to the oil pump. The filter has a recirculation port connected to the main control area of the case. It receives fluid from the main regulator exhaust. This provides fluid under pressure to aid the pump in higher efficiency operation. A fluid control valve prevents foaming of fluid by maintaining an oil pan level below the rotating components. The two piece chain drive cover prevents foaming by not allowing the chain to rotate in the fluid. A magnet on the underside of the chain cover collects unwanted magnetic material.

Main Control

The main control body contains the hydraulic solenoid valves. These valves direct fluid flow, restrict fluid flow and change fluid pressure. The main control receives signals from the solenoid valve body and changes those signals into hydraulic actions. These actions control the operation of the hydraulic clutches and the intermediate and overdrive band assembly. They also supply lubrication to the transaxle.

Servo - Low/Reverse

The low/reverse servo cushions the application of the low/reverse clutch when the transaxle is shifted to reverse gear.

Servo - 2-4

The 2-4 servo cushions the shift feel during intermediate and overdrive band applications.

Servo - Forward

The forward servo cushions the application of the forward clutch when the transaxle is shifted into D2 or 1.

Transaxle Electronic Control System

Electronic System Description

The gearshift timing, gearshift pressure (line pressure) and the solenoid valves of the torque converter lock-up clutch (TCC solenoid valve) in the CD4E transmission are controlled electronically by the powertrain control module (PCM) with its network of inputs and outputs. The transaxle control is separate from the engine control strategy in the PCM, although some of the input signals are shared. Some inputs come from sensors (mass air flow meter, coolant temperature sensor etc.) and inform the PCM about the load status and the operating conditions of the engine. Other inputs are based on driver inputs, such as accelerator pedal position which is relayed to the PCM by the throttle position (TP) sensor. Other inputs again come from the transmission itself, from sensors like the transmission range sensor (TR) (controlled by the position of the gear lever) and the transmission fluid temperature sensor (TFT)

Using all these input signals, the PCM can determine when the time and conditions are right for a shift or converter clutch application. The PCM can also determine the line pressure needed to optimize shift feel. In order to carry out these functions, the PCM controls five electronic solenoid valves - two ON/OFF solenoid valves for switching, one pulse-width modulated (PWM) solenoid valve for controlling the lock-up clutch, one electronic pressure control (EPC) solenoid valve for regulating the line pressure and a 3-2 shift timing/coast clutch solenoid valve for controlling the disengagement of the coast clutch and the co-ordinated disengagement of the direct clutch and the actuation of the low-intermediate brake band during a 3-2 shift.

Powertrain Control Module (PCM) - Inputs

• Transmission fluid temperature (TFT) sensor
• Transmission range (TR) sensor
• Brake on/off (BOO) switch
• Electronic ignition (EI) system
  -

  Crankshaft position (CKP) sensor
  -

  Ignition control module
• Mass air flow (MAF) sensor
• Throttle position (TP) sensor
• Transmission control switch (TCS)
• Air conditioning (A/C) Clutch
• Engine coolant temperature (ECT) sensor
• Turbine shaft speed (TSS) sensor

Powertrain Control Module (PCM) - Outputs

• Transaxle solenoid body assembly
  -

  Shift solenoid 1 (SS1)
  -

  Shift solenoid 2 (SS2)
  -

  Solenoid valve, electronic pressure control (EPC solenoid)
  -

  Solenoid valve, torque converter lock-up clutch (TCC solenoid)
  -

  3-2 Timing/coast clutch solenoid (3-2T/CCS)
• Transmission control indicator lamp (TCIL).

PCM inputs