deactivate CHRYSLER CARAVAN 2002 Service Manual

DESCRIPTION - ELECTRONIC VARIABLE
BRAKE PROPORTIONING
Vehicles equipped with ABS use electronic variable
brake proportioning (EVBP) to balance front-to-rear
braking. The EVBP is used in place of a rear propor-
tioning valve. The EVBP system uses the ABS sys-
tem to control the slip of the rear wheels in partial
braking range. The braking force of the rear wheels
is controlled electronically by using the inlet and out-
let valves located in the integrated control unit
(ICU).
DESCRIPTION - TRACTION CONTROL SYSTEM
Traction control reduces wheel slip and maintains
traction at the driving wheels at speeds below 56
km/h (35 mph) when road surfaces are slippery. The
traction control system reduces wheel slip by braking
the wheel that is losing traction.
HYDRAULIC SHUTTLE VALVES
Two pressure relief hydraulic shuttle valves are
included on vehicles with traction control. These
valves are located inside the HCU and cannot be ser-
viced separately from the HCU.
TRACTION CONTROL LAMP
The traction control function lamp is located in the
transmission range indicator display of the instru-
ment cluster, displaying TRAC, TRAC OFF or nei-
ther depending on system mode.
The TRAC OFF lamp is controlled by a Traction
Control Off switch that is a momentary contact type
switch. The Traction Control Off switch is located on
the steering column upper shroud.
OPERATION
OPERATION - ANTILOCK BRAKE SYSTEM
There are a few performance characteristics of the
Mark 20e Antilock Brake System that may at first
seem abnormal, but in fact are normal. These char-
acteristics are described below.
NORMAL BRAKING
Under normal braking conditions, the ABS func-
tions the same as a standard base brake system with
a diagonally split master cylinder and conventional
vacuum assist.
ABS BRAKING
ABS operation is available at all vehicle speeds
above 3±5 mph. If a wheel locking tendency is
detected during a brake application, the brake sys-
tem enters the ABS mode. During ABS braking,
hydraulic pressure in the four wheel circuits is mod-ulated to prevent any wheel from locking. Each
wheel circuit is designed with a set of electric sole-
noids to allow modulation, although for vehicle sta-
bility, both rear wheel solenoids receive the same
electrical signal. Wheel lockup may be perceived at
the very end of an ABS stop and is considered nor-
mal.
During an ABS stop, the brakes hydraulic system
is still diagonally split. However, the brake system
pressure is further split into three control channels.
During antilock operation of the vehicle's brake sys-
tem, the front wheels are controlled independently
and are on two separate control channels, and the
rear wheels of the vehicle are controlled together.
The system can build and release pressure at each
wheel, depending on signals generated by the wheel
speed sensors (WSS) at each wheel and received at
the controller antilock brake (CAB).
NOISE AND BRAKE PEDAL FEEL
During ABS braking, some brake pedal movement
may be felt. In addition, ABS braking will create
ticking, popping, or groaning noises heard by the
driver. This is normal and is due to pressurized fluid
being transferred between the master cylinder and
the brakes. If ABS operation occurs during hard
braking, some pulsation may be felt in the vehicle
body due to fore and aft movement of the suspension
as brake pressures are modulated.
At the end of an ABS stop, ABS is turned off when
the vehicle is slowed to a speed of 3±4 mph. There
may be a slight brake pedal drop anytime that the
ABS is deactivated, such as at the end of the stop
when the vehicle speed is less than 3 mph or during
an ABS stop where ABS is no longer required. These
conditions exist when a vehicle is being stopped on a
road surface with patches of ice, loose gravel, or sand
on it. Also, stopping a vehicle on a bumpy road sur-
face activates ABS because of the wheel hop caused
by the bumps.
TIRE NOISE AND MARKS
Although the ABS system prevents complete wheel
lockup, some wheel slip is desired in order to achieve
optimum braking performance. Wheel slip is defined
as follows: 0 percent slip means the wheel is rolling
freely and 100 percent slip means the wheel is fully
locked. During brake pressure modulation, wheel slip
is allowed to reach up to 25±30 percent. This means
that the wheel rolling velocity is 25±30 percent less
than that of a free rolling wheel at a given vehicle
speed. This slip may result in some tire chirping,
depending on the road surface. This sound should not
be interpreted as total wheel lockup.
Complete wheel lockup normally leaves black tire
marks on dry pavement. The ABS will not leave dark
5 - 86 BRAKES - ABSRS
BRAKES - ABS (Continued)
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²Ignition sense
²Intake Air Temperature Sensor
²Knock Sensor
²Leak Detection Pump Feedback
²Manifold Absolute Pressure (MAP) Sensor
²Park/Neutral (from transmission control module)
²PCI Bus
²Power Steering Pressure Switch
²Proportional Purge Sense
²SCI Receive
²Speed Control
²Throttle Position Sensor
²Torque Management Input (From TCM)
²Transaxle Control Module (TCM)
²Transaxle Gear Engagement (From TCM)
²Vehicle Speed (from transmission control mod-
ule)
NOTE: PCM Outputs:
²Air Conditioning Clutch Relay
²Automatic Shut Down (ASD) and Fuel Pump
Relays
²Data Link Connector (PCI and SCI Transmit)
²Double Start Override
²EGR Solenoid
²Fuel Injectors
²Generator Field
²High Speed Fan Relay
²Idle Air Control Motor
²Ignition Coils
²Leak Detection Pump
²Low Speed Fan Relay
²MTV Actuator
²Proportional Purge Solenoid
²SRV Valve
²Speed Control Relay
²Speed Control Vent Relay
²Speed Control Vacuum Relay
²8 Volt Output
²5 Volt Output
Based on inputs it receives, the powertrain control
module (PCM) adjusts fuel injector pulse width, idle
speed, ignition timing, and canister purge operation.
The PCM regulates the cooling fans, air conditioning
and speed control systems. The PCM changes gener-
ator charge rate by adjusting the generator field.
The PCM adjusts injector pulse width (air-fuel
ratio) based on the following inputs.
²Battery Voltage
²Intake Air Temperature Sensor
²Engine Coolant Temperature
²Engine Speed (crankshaft position sensor)²Exhaust Gas Oxygen Content (heated oxygen
sensors)
²Manifold Absolute Pressure
²Throttle Position
The PCM adjusts engine idle speed through the
idle air control motor based on the following inputs.
²Brake Switch
²Engine Coolant Temperature
²Engine Speed (crankshaft position sensor)
²Park/Neutral (transmission gear selection)
²Transaxle Gear Engagement
²Throttle Position
²Vehicle Speed (from Transmission Control Mod-
ule)
The PCM adjusts ignition timing based on the fol-
lowing inputs.
²Intake Air Temperature
²Engine Coolant Temperature
²Engine Speed (crankshaft position sensor)
²Knock Sensor
²Manifold Absolute Pressure
²Park/Neutral (transmission gear selection)
²Transaxle Gear Engagement
²Throttle Position
The automatic shut down (ASD) and fuel pump
relays are mounted externally, but turned on and off
by the powertrain control module through the same
circuit.
The camshaft and crankshaft signals are sent to
the powertrain control module. If the PCM does not
receive both signals within approximately one second
of engine cranking, it deactivates the ASD and fuel
pump relays. When these relays are deactivated,
power is shut off to the fuel injectors, ignition coils,
fuel pump and the heating element in each oxygen
sensor.
The PCM contains a voltage converter that
changes battery voltage to a regulated 8.0 volts. The
8.0 volts power the camshaft position sensor, crank-
shaft position sensor and vehicle speed sensor. The
PCM also provides a 5.0 volts supply for the engine
coolant temperature sensor, intake air temperature
sensor, manifold absolute pressure sensor and throt-
tle position sensor.
The PCM engine control strategy prevents reduced
idle speeds until after the engine operates for 320 km
(200 miles). If the PCM is replaced after 320 km (200
miles) of usage, update the mileage in new PCM. Use
the DRB scan tool to change the mileage in the PCM.
Refer to the appropriate Powertrain Diagnostic Man-
ual and the DRB scan tool.
8E - 12 ELECTRONIC CONTROL MODULESRS
POWERTRAIN CONTROL MODULE (Continued)
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AUTOSTICK SWITCH
DESCRIPTION
Autostick is a driver-interactive transaxle feature
that offers manual gear shifting capability. The con-
trol switch is part of the transaxle gear shift lever as
shown in (Fig. 172). It can only be serviced by replac-
ing the gearshift lever assembly. (Refer to 19 -
STEERING/COLUMN/GEAR SHIFT LEVER -
REMOVAL)
OPERATION
When the shift lever is moved into the Autostick
position (as indicated by the Shift Lever Position
Indicator in the cluster), the transaxle remains in
whatever gear it was using before Autostick was acti-
vated. The TCM sends a 5 volt signal through the
switch and then monitors the signal for voltage drop.
Each switch state (driver command) results in a spe-
cific voltage reading sensed by the TCM. The TCM
then determines transaxle operation (upshift/down-
shift/OD Lockout) based on their corresponding volt-
age. Refer to the following chart for corresponding
switch states and voltage readings:
Switch State Voltage Reading
Autostick DOWN
depressed0.3V-1.6V
Autostick UP depressed 1.6V-2.8V
Overdrive OFF9Lockout9
depressed2.8V-3.8V
All switches open 3.8V-4.8V
-Voltage values <.3V and >4.8V are considered
INVALID and will result in a DTC
Moving the switch up causes an upshift and mov-
ing the switch down causes a downshift. The instru-
ment cluster will illuminate the selected gear. The
vehicle can be launched in 1st, 2nd, or 3rd gear while
in the Autostick mode. The speed control is operablein 3rd and 4th gear Autostick mode. Speed control
will be deactivated if the transaxle is shifted to 2nd
gear. Shifting into OD position cancels the Autostick
mode, and the transaxle resumes the OD shift sched-
ule.
DRIVING CLUTCHES
DESCRIPTION
Three hydraulically applied input clutches are used
to drive planetary components. The underdrive, over-
drive, and reverse clutches are considered input
clutches and are contained within the input clutch
assembly (Fig. 173). The input clutch assembly also
contains:
²Input shaft
²Input hub
²Clutch retainer
²Underdrive piston
²Overdrive/reverse piston
²Overdrive hub
²Underdrive hub
Fig. 172 Autostick Switch Location (if equipped)
Fig. 173 Input Clutch Assembly
1 - INPUT SHAFT
2 - UNDERDRIVE CLUTCH
3 - OVERDRIVE CLUTCH
4 - REVERSE CLUTCH
5 - OVERDRIVE SHAFT
6 - UNDERDRIVE SHAFT
RS41TE AUTOMATIC TRANSAXLE21 - 237
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REAR CONTROL PANEL
With the rear control active, temperature selection
dictates indirectly the mode (floor or overhead air) of
the rear unit: a low temperature setting directs flow
to the overhead outlets and a high temperature set-
ting to the floor.
OPERATION - THREE ZONE ATC
Comfort temperature or perceived temperature is
affected by air flow, sun impinging on exposed skin,
etc. The air temperature may be higher or lower than
the comfort temperature. Three infrared sensors, two
in the instrument panel center stack, and one in the
overhead-mounted rear control panel, independently
measure the temperature of the driver, front passen-
ger, and rear compartment occupants to determine
their comfort level relative to the selected comfort
temperature. The HVAC computer in the control
module adjusts the air flow rate and temperature to
maintain the customer-perceived comfort tempera-
ture. The air temperature in the passenger compart-
ment at any time may be slightly higher or lower
than the comfort temperature. For instance, on
sunny summer days the air flow will probably be
cooler than the comfort temperature; on cold or
cloudy days and at night it will probably be slightly
warmer. Infrared Three-Zone Temperature Control
provides side-to-side and front-to-rear variation in
comfort temperature settings. The Infrared Three-
Zone Automatic Temperature Control fan provides a
continuously variable air flow rate to meet occupant
comfort requirements.
FRONT CONTROL PANEL
²AUTO HI/LO± This system features two sets of
automatic control logic that allow either a rapid cool-
down rate or a somewhat slower cool-down rate with
less fan noise. HI-AUTO controls the system to reach
its assigned temperature quickly with a higher fan
speed. LO-AUTO controls the system to reach its
assigned temperature somewhat slower with less fan
noise. Both modes will automatically engage auto
recirculation.
²DE-FROST± The front de-frost function is
active when the rear window defogger function is
active or when the defog/defrost mode is selected.
²RECIRC± The RECIRC button will close the
air inlet door. If the system is in auto recirc (indica-
tor being displayed automatically), pressing the man-
ual recirc button will disable the auto recirc function
until one of the auto keys are pressed or the ignition
is cycled. If Auto HI/LO is pressed while manual
recirc is active, manual recirc will be deactivated.
²REAR WINDOW DEFOGGER± Pushing the
button sends a PCI bus message to the Intelligent
Power Module which controls the Rear WindowDefogger and side view mirror (if equipped) circuitry.
The defogger function will be active for 10 minutes
and can be turned off by a switch press. The defogger
will function while the control is in the OFF mode.
²FAN/MODE± The Fan and Mode knobs have
17 manual selectable positions. Manually changing
either of the rotary knobs for mode or fan speed set-
tings makes control of that function alone manual for
as long as the ignition is on. If only one is changed
manually, the other remains under automatic control.
Pressing the HI-AUTO/LO-AUTO rocker switch
restores full automatic control.
²REAR CONTROL± When the Rear System
control knob is moved to the OFF position, there will
be a delay of approximately 1 second before the sys-
tem actually turns off. This delay is to prevent an
undesired blower dropout if the knob is moved
through OFF to the other selections.
²BLOWER DELAY TIMER± The word DELAY
is displayed at start-up to signify that the system is
waiting so that cold air will not be blowing. This tells
the operator that it is unnecessary to turn the sys-
tem off, raise the temperature setting or turn the fan
speed setting down to prevent cold air from blowing.
A countdown in minutes and seconds until the engine
is warm enough to begin delivering heat to the pas-
sengers alternates with the DELAY message at 25
second intervals. This countdown is based on actual
measurement of the rate of engine coolant tempera-
ture change. During the delay time, Defrost mode is
selected and the fan operates at a low speed to keep
the windshield fog free.
REAR CONTROL PANEL
Primary control of the rear compartment unit is in
the instrument panel center stack. The rear unit con-
trol knob there allows the driver to turn the rear
unit off, allow control by the intermediate seat occu-
pants by switching to the REAR position, or provide
fully automatic control based on the temperature set-
ting shown on the front control display.
²REAR CONTROL± Selecting automatic control
of the rear unit at the instrument panel, illuminates
a Locked Padlock in the rear control panel display.
Selecting REAR activates the rear control panel and
the Padlock then appears unlocked.
²FAN KNOB± The rear fan control has Off and
AUTO positions and a range of manual speed set-
tings that override the AUTO setting.
²MODE KNOB± The mode control allows inter-
mediate seat occupants to manually override the
automatic mode and select any balance of air flow
between overhead and floor outlets from full over-
head to full floor.
²SET TEMP± The rear set temp control will
operate identical to the front controls. If the front
24 - 4 HEATING & AIR CONDITIONINGRS
HEATING & AIR CONDITIONING (Continued)
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