Cruise Control System - Speed Control: Overview Ford Escape I рестайлинг

Principles of Operation

The stoplamp switch is normally open. When the brake pedal is applied with the speed control system engaged, the stoplamp switch closes (to battery voltage), putting the speed control in the stand-by mode.

The clockspring provides the electrical interface between the steering column wiring and the speed control switches in the steering wheel.

The inputs to the speed control actuator required to operate the speed control system are the

1. speed control switches
2. digital transmission range (TR) sensor (automatic transaxle)
3. clutch pedal position (CPP) sensor (manual transaxle)
4. stoplamp switch
5. speed control deactivator switch
6. speed signal from the anti-lock brake system (ABS) module

Normal Operation

The speed control actuator sends and receives signals to the speed control switches through circuits 151 (LB/BK) and 848 (DG/OG). Voltage to the speed control actuator is supplied through circuit 601 (LB/PK) from the SJB. Ground for the speed control actuator is through circuit 57 (BK).

Voltage for the speed control servo clutch (internal to the speed control actuator) is supplied by the SJB to the speed control deactivator switch through circuits 101 (GY/YE) and 998 (YE/LG). The speed control deactivator switch (closed when the brake pedal is not applied) then routes the voltage to circuit 248 (TN/OG) and then to circuit 810 (RD/LG) to the speed control actuator. When the brake pedal is firmly pressed, the speed control deactivator switch opens and voltage is no longer supplied to the speed control servo clutch.

When the brake pedal is applied, the stoplamp switch routes voltage to circuit 511 (LG) to illuminate the stoplamps and send a voltage signal to the speed control actuator. When the speed control actuator receives this input, the speed control actuator goes into a stand-by mode.

The speed control actuator sends a voltage reference signal through circuit 199 (LB/YE). The speed control system will not engage if circuit 199 (LB/YE) is grounded, and goes into a stand-by mode if the speed control system has a set speed that it is maintaining. When the transaxle is placed in NEUTRAL (automatic transaxle), the digital transmission range (TR) sensor routes the signal to ground through circuit 57 (BK). When the clutch is applied, the clutch pedal position switch (CPP) routes the signal to ground through circuit 359 (GY/RD) and then to the powertrain control module (PCM). The PCM provides a ground internally for this circuit.

The speed control actuator receives the speed signal from the ABS module through circuit 679 (GY/BK).

Under normal operation the speed control actuator adjusts the speed control cable which controls the throttle body.

Note. Tapping the brake pedal deactivates the speed control. It is necessary to apply the brakes in order to slow the vehicle down.

The speed control actuator sends a voltage reference signal through circuit 511 (LG). The stoplamps provide a ground path that enables speed control operation. When the brake pedal is applied, the voltage goes high and speed control goes into standby mode.

Voltage for the speed control servo clutch (internal to the speed control actuator) is supplied by the SJB to the speed control deactivator switch through circuits 101 (GY/YE) and 998 (YE/LG). The speed control deactivator switch (closed when the brake pedal is not applied) then routes the voltage to circuit 248 (TN/OG) and then to circuit 810 (RD/LG) to the speed control actuator. When the brake pedal is firmly pressed, the speed control deactivator switch opens and voltage is no longer supplied to the speed control servo clutch.

The speed control actuator sends a voltage reference signal through circuit 199 (LB/YE). When the clutch is applied, the clutch pedal position (CPP) switch closes and routes the signal to ground through circuit 359 (GY/RD). Ground is supplied by the powertrain control module (PCM).

Under normal operation the speed control actuator sends a signal through circuit 151 (LB/BK) to the speed control switches, which passes through the clockspring. The return signal is sent back through the clockspring to circuit 848 (DG/OG). When 2 buttons are pressed simultaneously, the speed control system enters a stand-by mode.

Under normal operation the speed control actuator adjusts the speed control cable which controls the throttle body.

When the speed control actuator carries out the self-test, a voltage signal is sent through circuit 511 (LG). Circuit 511 (LG) carries the signal to the stoplamp bulbs, which then is routed to ground. If the signal fails to be grounded, flash code 2 is set by the speed control actuator.

Voltage for the speed control servo clutch (internal to the speed control actuator) is supplied by the smart junction box (SJB) to the speed control deactivator switch through circuits 101 (GY/YE) and 998 (YE/LG). The speed control deactivator switch (closed when the brake pedal is not applied) then routes the voltage to circuit 248 (TN/OG) and then to circuit 810 (RD/LG) to the speed control actuator. When the brake pedal is firmly pressed, the speed control deactivator switch opens and voltage is no longer supplied to the speed control servo clutch.

When the speed control actuator carries out the self-test, it checks for continuity to ground through circuit 199 (LB/YE). This is accomplished by sending a voltage reference signal to the clutch pedal position (CPP) switch (manual transaxle) or the transmission range (TR) sensor (automatic transaxle).

When the clutch is applied, the signal is routed through circuit 359 (GY/RD) to the powertrain control module (PCM). The PCM provides an internal ground.

When the automatic transaxle is in NEUTRAL, the signal is routed through circuit 57 (BK) to ground.

The speed control system is controlled by the powertrain control module (PCM).

The speed control system is enabled/disabled by the speed control switches, the speed control deactivator switch, the stoplamp switch, and the parking brake switch.

The speed control switch functions

1. turn on the speed control system
2. set and maintain the desired vehicle speed
3. accelerate the vehicle speed
4. decelerate the vehicle speed
5. tap-up/tap-down the vehicle speed
6. resume the prior vehicle speed
7. turn off the vehicle speed control system
8. cancel the speed control

Pressing and releasing the ON switch turns the system on. Pressing and releasing the SET/ACCELERATE switch while the vehicle is traveling, sets the desired speed.

Tapping the SET/ACCELERATE or COAST/DECELERATE buttons, while in the set mode, increases or decreases the maintained vehicle speed by 1.6 km/h (1 mph) per tap for US instrument clusters, or 2.0 km/h (1.24 mph) per tap for metric instrument clusters. If the respective button is pressed and held, the vehicle speed continues to accelerate or decelerate until the button is released.

Pressing the OFF switch, or positioning the ignition switch in the OFF position, turns the speed control off. Pressing the brake pedal puts the system in the standby mode. Pressing the RESUME button when the system is in standby mode causes the vehicle to accelerate or decelerate until the last set speed is resumed. Resume does not function if the OFF button is pressed, the ignition switch is in the OFF position, or if the current vehicle speed is below the minimum operational speed.

The inputs to the PCM for the speed control system are the

1. parking brake signal from the instrument cluster
2. anti-lock brake system (ABS) module
3. speed control deactivator switch
4. stoplamp switch
5. speed control switches

The outputs from the PCM for the speed control system are the

1. instrument cluster
2. throttle command

When the gasoline motor is powering the vehicle and the speed control is active, the speed control system does not require an electronic actuator for electronic throttle control (ETC) vehicles. The throttle position is completely controlled by the PCM. The speed control electronics are contained entirely within the ETC subsystem.

When the electric traction motor is powering the vehicle and the speed control is active, the electronic actuator corrects for deviations in the actual vehicle speed by proportionally applying wheel torque. The control electronics modulate the wheel torque to minimize error between the actual vehicle speed and the desired speed.

The PCM strategy uses the powertrain control for smooth accelerations.

The PCM sends a requested controller area network (CAN) vehicle speed control set speed status (enable/disable) to the instrument cluster whenever the speed control set telltale should be turned ON or OFF.

The driver commands the speed control system by pressing the steering-wheel mounted switches. The steering wheel switches are hardwired to the PCM.

The speed control system operates in the following modes

1. ON
2. OFF
3. SET/ACCELERATE
4. COAST/DECELERATE
5. RESUME
6. SOFT DEACTIVATE
7. STANDBY
8. HARD DEACTIVATE

When the speed control is in the ON mode and the PCM receives a SET/ACCELERATE or COAST/DECELERATE switch input, the speed control system enters the SET mode and maintains the present vehicle speed (provided the vehicle speed is within the system operating range). When the PCM receives an SET/ACCELERATE switch input, the speed control system will accelerate the vehicle 1.6 to 2.7 km/second (1.00 to 1.68 miles/second) on level roads. The speed control system continues to accelerate the vehicle until the switch is no longer pressed and then maintains that vehicle speed. If the duration of the switch input is less than 640 ms the speed control system increases the vehicle speed by 1.6 km/h (1 mph) for US instrument clusters, or 2.0 km/h (1.24 mph) for metric instrument clusters. When the system is in the STANDBY mode and a RESUME switch input is received, the speed control system transitions into the SET mode and modifies the vehicle speed to resume the last set vehicle speed, provided the speed control system has previously been in the SET mode in the current ON cycle.

When the PCM receives a COAST/DECELERATE switch input, the speed control system decreases the vehicle speed 1.6 to 2.7 km/second (1.00 to 1.68 miles/second) on level roads. Once the switch is no longer pressed, the speed control system ceases vehicle deceleration and maintains the present vehicle speed. If the duration of the switch input is less than 640 ms, the speed control system decreases the vehicle speed by 1.6 km/h (1 mph) for US instrument clusters, or 2.0 km/h (1.24 mph) for metric instrument clusters.

In the event of an OFF command or a deactivation request from any source except a brake pedal tap, the system carries out a hard deactivation and immediately returns control to the accelerator pedal.

The accelerator pedal can be used to override the set speed control. Once the speed control is SET and the operators foot is removed from the accelerator pedal, the accelerator pedal will fully return to its at rest (idle) position. The operator may override the speed control by pressing the accelerator pedal to a position that represents a wheel torque command greater than the speed control demand. A certain amount of free-play (dead space) may be felt by the driver in this mode.

The speed control system provides self-diagnostics. The speed control is disabled anytime an error is detected in the system. No cluster telltale or message center messages are displayed when faults occur. Fault codes are logged by the PCM.

The PCM sends a signal through circuit 151 (LB/BK) to the speed control switches which pass through the clockspring. The return signal is sent through circuit 848 (DG/OG) and the clockspring.