Chrysler Town & Country/Voyager, Dodge Caravan, Plymouth Voyager. Manual — part 171
ANTI-LOCK SYSTEM RELAYS AND WARNING
LAMPS
PUMP/MOTOR RELAY
Pump/Motor power is supplied by the Pump/Motor
Relay. The Pump/Motor relay is located in front of the
left shock tower (Fig. 9). The relay coil is energized by
a ground from the Dual Function Pressure Switch.
SYSTEM RELAY
The (ABS) Modulator Valves and Anti-Lock Warning
Lamp Relay are controlled through a System Relay.
The System relay is located on the top left inner fender
behind the headlight (Fig. 9). The system relay pro-
vides power to the (CAB) for modulator valve operation
(pins 47 and 50) after the start-up cycle when the
ignition is turned on.
ANTI-LOCK WARNING LAMP RELAY
The Anti-Lock Warning Lamp is controlled by the
Yellow Light Relay. See (Fig. 9) for location behind the
left headlight. With the relay de-energized, the lamp is
lit. When the system relay is energized by the (CAB),
the Anti-Lock Warning Lamp relay is energized, and
the lamp is turned off. Thus, the lamp will be lit if the
(CAB) is disconnected or if a system fault causes (ABS)
function to be turned off, or if the system relay fails
open.
ANTI-LOCK WARNING LAMP OFF
System Relay (normally open) and Yellow Light
Relay (normally closed) Energized.
From pin 57 the (CAB) energizes the system relay
coil. The current flow in the coil closes the system relay.
Current is then provided to pins 47 and 50 of the (CAB)
to provide power to the modulator valves. This current
also energizes the Yellow Light Relay coil. The current
flow in the yellow light relay coil opens the Anti-Lock
Warning Lamp Relay Switch. This breaks the ground
path to the Anti-Lock Warning Lamp and the lamp is
turned off.
The (CAB) by itself, also can turn on the Anti-Lock
Warning Lamp. The (CAB) can turn on the Anti-Lock
Warning Lamp by providing a ground at pin 15.
ANTI-LOCK WARNING LAMP ON
System Relay and Anti-Lock Warning Lamp
Relay De-Energized.
When the Amber Anti-Lock Warning Lamp is on,
there is no current flow from the (CAB) at pin 57. The
system relay coil is NOT energized. No current flows to
pins 47 and 50 (modulator valve power), or to the
Anti-Lock Warning Lamp relay coil. Thus, the Anti-
Lock Warning Lamp Relay is not energized. The Anti-
Lock Warning Lamp is grounded through the Anti-
Lock Warning Lamp relay contacts. The Anti-Lock
Warning Lamp is illuminated.
Fig. 9 Pump/Motor and Anti-Lock System Relays
.
ANTI-LOCK BRAKES
5 - 67
ANTI-LOCK
SYSTEM
RELAY
WIRING
SCHEMATIC
5 - 68
ANTI-LOCK BRAKES
.
ABS HYDRAULIC CIRCUITS AND VALVE OPERA-
TION
Through the following operation descriptions and
diagrams. The function of the various hydraulic control
valves in the ABS system will be described. The fluid
control valves mentioned below, control the flow of
pressurized brake fluid to the wheel brakes during the
different modes of Anti-Lock Braking.
NORMAL BRAKING
ISOLATION VALVES
Open to primary and secondary master cylinder
brake fluid supply (Fig. 10)
DECAY AND BUILD VALVES
Closed, not allowing for the build-up or release of
brake fluid supply (Fig. 10).
The brake pedal is applied. The travel of the brake
pedal closes primary, secondary and booster servo
circuits from fluid supply at the fluid reservoir. Brake
fluid from the primary and secondary circuits flows
through the open isolation valves and applies the
wheel brakes. Fluid from the booster servo circuit does
not flow to the wheel brakes. The fluid flow is blocked
by the closed build valves and check valves.
POWER ASSIST
The boost control valve shuttles between its three
positions to provide power assisted braking (Fig. 10).
ABS BRAKING-BUILD PRESSURE
ISOLATION VALVES
Closed, isolating wheel brakes from master cylinder
primary and secondary fluid supplies and open to
booster servo circuit pressure through open build
valves (Fig. 11)
DECAY VALVES
Closed, not allowing the escape of pressurized fluid
supply from the hydraulic system (Fig. 11).
BUILD VALVES
Open, allowing booster servo circuit pressure to flow
to wheel brakes through the isolation valves (Fig 11).
Fig. 10 Normal Braking - Hydraulic Control
.
ANTI-LOCK BRAKES
5 - 69
POWER ASSIST
The boost control valve shuttles between its three
positions to provide power assisted braking (Fig. 11).
ABS BRAKING-HOLD PRESSURE
For explanation purposes we will assume all speed
sensors are sending the same wheel speed information,
requiring the same modulation at the same rate.
ISOLATION VALVES
Closed, isolating the wheel brakes from the master
cylinder primary and secondary fluid supplies. Build
and decay valves are closed preventing any fluid from
reaching the open isolation valves (Fig. 12).
DECAY AND BUILD VALVES
Closed, not allowing fluid supply to reach the open
isolation valves (Fig. 12).
ABS BRAKING-DECAY PRESSURE
ISOLATION VALVES
Closed, isolating the wheel brakes from the master
cylinder primary and secondary fluid supplies (Fig. 13)
DECAY VALVES
Open, allowing release of fluid pressure through
decay valve to the fluid reservoir (Fig. 13)
BUILD VALVE
Closed, blocking booster servo circuit fluid to wheel
brakes (Fig. 13).
Fig. 11 Build Pressure - Hydraulic Control
5 - 70
ANTI-LOCK BRAKES
.
Нет комментариевНе стесняйтесь поделиться с нами вашим ценным мнением.
Текст