Service Manuals, User Guides, Schematic Diagrams or docs for : . Car Manuals Subaru Impreza 2001-2002.2004-2007 Approved Subaru Impreza 2004 WRX STi 08. MECHANISM AND FUNCTION 63. CRUISE CONTROL SYSTEM (Sti) 01. Cruise Control
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W1860BE.book Page 2 Tuesday, January 28, 2003 11:01 PM
CRUISE CONTROL
CRUISE CONTROL SYSTEM
1. Cruise Control
A: OPERATION
The cruise control system automatically controls the vehicle speed. It allows the vehicle to run at
a constant speed without need for the driver to keep the accelerator pedal depressed.
The cruise control system is controlled by the engine control module (ECM).
When the driver has activated the system and made a desired speed setting, the engine control
module (ECM) compares the actual vehicle speed detected by the speed sensor with the preset
speed in the engine control module (ECM) memory, and then generates a signal according to the
difference between the two speeds.
This signal is transmitted to the electronic control throttle.
The electronic control throttle operates the throttle valve as necessary to keep the preset vehicle
speed.
B: LOCATION OF COMPONENTS
(3)
(2)
(1)
(5)
(4)
CC-00205
(1) Engine control module (ECM)
(2) Cruise control command switch (with built-in MAIN switch)
(3) Cruise indicator light and cruise set indicator light
(4) Stop light and brake switch
(5) Clutch switch
CC(STi)-2
W1860BE.book Page 3 Tuesday, January 28, 2003 11:01 PM
CRUISE CONTROL
CRUISE CONTROL SYSTEM
C: CONTROL AND OPERATION
Vehicle speed When the actual vehicle speed is higher than the set speed, the throttle valve of the electronic control throttle
control moves in the closing direction by the amount corresponding to the difference between the two speeds. When
the actual vehicle speed is lower than the set speed, the throttle valve of the electronic control throttle moves
in the opening direction by the amount corresponding to the difference between the two speeds.
Speed set func- When the SET/COAST switch is pressed while the vehicle is running at a speed greater than 40 km/h (25 MPH)
tion and the MAIN switch is ON, the cruise control is set at the current vehicle speed (this speed becomes the
(SET function) "memorized speed") and the vehicle maintains this speed thereafter.
Resume control When the RESUME/ACCEL switch is turned ON after the cruise control is temporarily cancelled, the vehicle
function speed returns to the memorized speed which was stored just before the cruise control was cancelled. This oc-
(RESUME func- curs only when the vehicle is running at a speed greater than 32 km/h (20 MPH). In the following cases, how-
tion) ever, the memorized speed is cleared.
(1) Ignition switch is turned OFF
(2) MAIN switch is turned OFF
(3) Abnormality in the system is detected.
Deceleration con- When the SET/COAST switch is pressed for a prolonged time while the vehicle is governed by the cruise con-
trol function (1) trol, the memorized speed of the cruise control is changed to the decreased vehicle speed value reached at
(COASTING the moment the switch is released. However, the cruise control is cancelled when the vehicle speed becomes
function) lower than the lower limit of the speed setting range.
Deceleration con- When the SET/COAST switch is pressed for a short time while the vehicle is governed by the cruise control,
trol function (2) the cruise control subtracts a certain amount from the memorized speed to obtain a new value. However, when
(TAP DOWN the actual vehicle speed largely differs from the memorized speed, the actual speed becomes the new mem-
function) orized speed of the cruise control.
Acceleration con- When the RES/ACCEL switch is pressed for a prolonged time while the vehicle is governed by the cruise con-
trol function (1) trol, the memorized speed of the cruise control is changed to the increased vehicle speed value reached at the
(ACCELERAT- moment the switch is released. However, when the vehicle speed is higher than the upper limit of the speed
ING function) setting range, the upper limit becomes the memorized speed of the cruise control.
Acceleration con- When the RES/ACCEL switch is pressed for a short time while the vehicle is governed by the cruise control,
trol function (2) the cruise control adds a certain amount to the memorized speed to obtain a new value. However, when the
(TAP UP function) actual vehicle speed largely differs from the memorized speed, the cruise control maintains the former memo-
rized speed.
Cruise control When any of the following conditions is met, the cruise control is cancelled.
cancel function (1) Stop light switch ON (brake pedal depressed) (2) Brake switch OFF (brake pedal depressed) (3) Clutch
switch OFF (clutch pedal depressed) (4) Neutral switch ON (shift lever moved to neutral) (5) CANCEL switch
ON (command switch pulled) (6) Ignition switch OFF (7) MAIN switch OFF (8) Transmission gear in 1st or
reverse. (9) Actual vehicle speed drops below 32 km/h (20 MPH) (10) Abnormality in the system is detected
CC(STi)-3
W1860BE.book Page 4 Tuesday, January 28, 2003 11:01 PM
CRUISE CONTROL
CRUISE CONTROL SYSTEM
D: SCHEMATIC
(1) (2)
(1)
(5)
(3) (4) (6)
(7)
(12)
(8)
(9)
(13)
(14)
(16)
(15)
(17)
(18)
(19) (20)
(10)
(11)
(21) CC-00206
CC(STi)-4
W1860BE.book Page 5 Tuesday, January 28, 2003 11:01 PM
CRUISE CONTROL
CRUISE CONTROL SYSTEM
(1) Battery (12) Electronic control throttle
(2) Ignition switch (13) Vehicle speed sensor
(3) Cruise indicator light (14) Vehicle speed signal
(4) Cruise set indicator light (15) Engine control module (ECM)
(5) Main relay (16) MAIN switch
(6) Starter (17) RESUME/ACCEL switch
(7) Clutch switch (18) CANCEL switch
(8) Clutch pedal (19) SET/COAST switch
(9) Stop light and brake switch (20) Cruise control command switch
(10) Brake pedal (21) Ground
(11) Neutral switch
CC(STi)-5
W1860BE.book Page 6 Tuesday, January 28, 2003 11:01 PM
CRUISE CONTROL
CRUISE CONTROL SYSTEM
E: COMMAND SWITCH (CRUISE CONTROL LEVER)
When the vehicle is driven with the cruise control activated, the command switch controls its op-
eration. It inputs MAIN signal, SET/COAST signal, ACCEL/RESUME signal or CANCEL signal to
the engine control module (ECM).
When the cruise control MAIN switch is turned ON, the cruise set indicator light in the combination
meter illuminates. Also, when the cruise control is set, the cruise indicator light in the combination
meter illuminates.
(2) (4)
(3) (5)
+B (6)
(1) (9)
(7)
+IGN
(8)
CC-00207
(1) Command switch (6) CANCEL
(2) Horn relay (7) RESUME/ACCEL
(3) Horn (8) MAIN
(4) Horn switch (9) Engine control module (ECM)
(5) SET/COAST
The command switch is located on the right side of the steering wheel, so the driver can operate
it without releasing hands from the steering wheel.
The command switch is a self-returning lever type.
1. MAIN SWITCH
When the switch is pushed once the cruise control system turns ON and becomes ready to set the
cruise control. When the switch is pushed again the cruise control turns OFF.
2. RESUME/ACCEL AND SET/COAST SWITCH
Each switch contact is held closed as long as the lever is kept pressed in the relevant direction and
resulting current is applied as a signal to the engine control module (ECM).
3. CANCEL SWITCH
All the switch contacts are closed as long as the lever is pulled toward the CANCEL position (toward
the driver). This causes the RESUME/ACCEL and SET/COAST ON signals to be sent to the engine
control module (ECM) simultaneously.
CC(STi)-6
W1860BE.book Page 7 Tuesday, January 28, 2003 11:01 PM
CRUISE CONTROL
CRUISE CONTROL SYSTEM
F: CANCEL SIGNALS
The cancel signal deactivates the cruise control function. Operating any of the following switches
results in generation of the cancel signal. On receiving the signal, the engine control module (ECM)
cancels the cruise control function.
Stop light switch
Brake switch
Clutch switch
Neutral switch
MAIN switch (OFF operation)
Command switch (CANCEL position)
Ignition switch (OFF operation)
G: VEHICLE SPEED SENSOR
The vehicle speed sensor is installed on the transmission, and sends signal to the engine control
module (ECM) which uses it in controlling the cruise control function.
H: ENGINE CONTROL MODULE (ECM)
Based on signals from the related switches and sensors, the engine control module (ECM) con-
trols all the following control functions:
Constant speed control; speed setting control; deceleration control; acceleration control; resume
control; manual cancel control; low speed limit control; electronic control throttle control
The engine control module (ECM) (A) is located in the legroom of the front passenger's seat.
(A)
CC-00208
CC(STi)-7
W1860BE.book Page 8 Tuesday, January 28, 2003 11:01 PM
CRUISE CONTROL
CRUISE CONTROL SYSTEM
I: FAIL-SAFE FUNCTION
The cruise control system has a fail-safe function that cancels the cruise control operation when any
of the following conditions occurs.
1. CONFLICT BETWEEN CRUISE CONTROL SWITCHES AND CANCELLATION SIGNAL
GENERATING SWITCHES
The cruise control system is deactivated if any of the cruise control switches (SET/COAST, RE-
SUME/ACCEL, and CANCEL switches) is turned ON while any of the cancellation signal generating
switches (brake, stop light, clutch, and neutral switches) is being operated. The system is re-acti-
vated when the cruise control switch is turned OFF and then turn ON again after the cancellation
signal generating switch has been returned to its released position.
When the MAIN switch is turned ON while any of the command switches is in the ON position,
the cruise control system is deactivated. The system deactivating function is retained until the MAIN
switch is turned OFF.
2. ABNORMALITIES IN ELECTRIC CIRCUITS
The cruise control system is deactivated and the set speed is also canceled if any of the following
abnormalities occurs in the system's electric circuits.
The system deactivation function is retained until the ignition switch is turned OFF.
Abnormality of the command switch is detected.
Abnormality of the stop light switch and brake switch is detected.
Abnormality of the neutral switch is detected.
Abnormality of the ignition switch is detected.
Change in vehicle speed signal is detected.
Abnormality in any of the engine related sensors is detected.
Abnormality of the brake switch input circuit in the engine control module (ECM) is detected.
The MAIN switch and command switch were already ON when the ignition switch is turned ON.
3. CRUISE CONTROL CANCEL FUNCTION
When any of the following conditions is met, the cruise control is cancelled.
To set the cruise control again, the vehicle speed must be returned to within the speed setting
range and necessary conditions must be met.
Abnormal engine speed acceleration is detected.
The vehicle speed has dropped below the lower control limit during cruise control driving.
The vehicle has been running at speed higher than the set speed for an abnormally long time dur-
ing cruise controlled driving.
The set speed became impossible to be maintained for some reason (steep upgrade, hand brake
operation, abnormal engine power drop, etc.).
CC(STi)-8
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