Dodge Dakota 2001, Service Manual

Page: 205 / 2307

RWAL VALVE
DESCRIPTION
The valve is located on the drivers side inner
fender under the hood. The valve modulates hydrau-
lic pressure to the rear brakes during an RWAL stop.
OPERATION
If the CAB senses that rear wheel speed decelera-
tion is excessive, it will energize an isolation solenoid
by providing battery voltage to the solenoid. This
prevents a further increase of driver induced brake
pressure to the rear wheels. If this initial action is
not enough to prevent rear wheel lock-up, the CAB
will momentarily energize a dump solenoid (the CAB
energizes the dump solenoid by providing battery
voltage to the solenoid). This opens the dump valve
to vent a small amount of isolated rear brake pres-
sure to an accumulator. The action of fluid moving to
the accumulator reduces the isolated brake pressure
at the wheel cylinders. The dump (pressure venting)
cycle is limited to very short time periods (millisec-
onds). The CAB will pulse the dump valve until rear
wheel deceleration matches the desired slip rate pro-
grammed into the CAB. The system will switch to
normal braking once wheel locking tendencies are no
longer present.
A predetermined maximum number of consecutive
dump cycles can be performed during any RWAL
stop. If excessive dump cycles occur, a DTC will be
set and stored in the CAB memory. If during a RWAL
stop, the driver releases the brake pedal, the reset
switch contacts will open. This signal to the CAB is
an indication that pressure has equalized across the
RWAL valve. The CAB will then reset the dump cycle
counter in anticipation of the next RWAL stop. Addi-
tionally, any fluid stored in the accumulator will
force its way past the dump valve, back into the
hydraulic circuit and return to the master cylinder.
A fuse internal to the CAB, provides a fail-safe
device which prevents unwanted control over the iso-
lation and dump solenoids. The fuse is in series with
the isolation and dump solenoids output circuits. If
the internal fuse is open, the CAB cannot provide
voltage to energize either solenoid and RWAL stops
are prevented. If the fuse is open, the braking system
will operate normally but without antilock control
over rear brake pressure.
REMOVAL
(1) Remove RWAL valve harness connector from
the RWAL controller.
(2) Remove the brake lines from the valve.
(3) Remove the valve mounting bolt (Fig. 13) and
remove the valve from the bracket.
INSTALLATION
(1) Position the valve on the bracket and install
the mounting bolt. Tighten the mounting bolt to
20-27 N·m (15-20 ft. lbs.).
(2) Install the brake lines and tighten to 19 N·m
(170 in. lbs.).
(3) Install the RWAL valve harness connector into
the RWAL controller.
(4) Bleed base brake system, (Refer to 5 - BRAKES
- STANDARD PROCEDURE).
Fig. 13 RWAL Valve
1 - RWAL VALVE
2 - MOUNTING BOLT
3 - BRAKE LINES
5 - 42 BRAKES - ABS
AN