Chrysler RAM TRUCK 2500 1994 Service Manual page 161

§ - 2 BRAKES
Combination Waive
A combination valve is used on all models. The
valve consists of a front brake metering (hold-off)
valve and a front/rear pressure differential switch.
A1TIL0CI BRAKE SYSTEMS
Two new antilock brake systems are used on BR
models. A rear wheel antilock (RWAL) brake system
is standard on all models. An all-wheel antilock
brake system (ABS) is available as an option. Both
antilock systems are manufactured and supplied by
the Kelsey-Hayes Corporation.
The RWAL and ABS antilock systems are designed
to retard wheel lockup during periods of high wheel
slip when braking. Retarding wheel lockup is accom­
plished by modulating fluid pressure to the wheel
brake units. Refer to the antilock brake sections for
operation and service information.
The RWAL antilock system uses one valve. The
ABS antilock system uses two valves. Refer to the
appropriate antilock brake section for valve opera­
tion, diagnosis and service procedures.
BRAKE WARNING LIGHTS
A red warning light is used to alert the driver i f a
pressure differential exists between the front and
rear hydraulic systems. The light also alerts the
driver when the parking brakes are applied. The
light is located at the left side of the instrument clus­
ter.
An amber warning light is used for the antilock
system. This light is located i n the same side of the
instrument cluster as the red indicator light. The an­
tilock light alerts the driver i f a system fault occurs.
BRAKE FLUiD/LUBRICAlTS/CLEANllG S0LVE1TS
Recommended fluid for all BR models is Mopar
brake fluid or equivalent meeting SAE standard
J1703 and Federal standard DOT 3.
Use Mopar multi mileage grease to lubricate cali­
per slide surfaces, drum brake pivot pins and shoe
contact points on the backing plates. Use GE 661 or
Dow 111 silicone grease (or equivalent) on caliper
bushings and mounting bolts.
Use Mopar brake cleaner, or denatured alcohol to
clean or flush brake system components. These are
the only cleaning materials recommended.
CAUTION: Never use gasoline, kerosene, methyl al­
cohol, motor oil, transmission fluid, or any fluid
containing mineral oil to clean the system compo­
nents. T h e s e fluids damage rubber c u p s and seals.
If system contamination is suspected, check the
fluid for dirt, discoloration, or separation into dis­
tinct layers. Drain and flush the system with new
brake fluid if contamination is suspected.
MODEL IDENTIFICATION
Different model number/capacity designations are
used for 1994 trucks. The new designations are:
• 1500 identifies 1/2 ton models
• 2500 identifies 3/4 ton models
• 2500 identifies one ton models
The model number and capacity ratings are used
throughout this group to identify, differentiate from,
or indicate application of a specific brake component.
BRAKE ADJUSTMENTS AND BLEEDING
PROCEDURES
Drum brake adjustment and brake bleeding proce­
dures are no longer located i n a separate section. Re­
fer to the Drum Brake service section for adjustment.
Refer to the RWAL or ABS Brake section for the ap­
plicable bleeding techniques.
Different brake bleeding procedures are required
for the RWAL and ABS antilock systems. Refer to the
appropriate procedure when brake bleeding is neces­
sary.
Parking brake and drum brake adjustment proce­
dures are located i n the pertinent section. Refer to
the Parking Brake section for the cable adjustment
procedure. Refer to the Drum Brake Section for shoe
adjustment procedures with a brake gauge.
BRAKE SAFETY PRECAUTIONS
WARNING: ALTHOUGH A S B E S T O S F R E E B R A K E -
LINING IS FACTORY INSTALLED ON A L L B R MOD­
E L S , E X E R C I S E C A R E WHEN REPAIRING A
V E H I C L E WITH PRIOR B R A K E S E R V I C E . SOME A F ­
T E R MARKET BRAKELINING MAY CONTAIN A S ­
B E S T O S . A S A RESULT, DUST AND DIRT ON
B R A K E PARTS MAY CONTAIN A S B E S T O S F I B E R S .
BREATHING E X C E S S I V E CONCENTRATIONS O F
A S B E S T O S F I B E R S CAN C A U S E S E R I O U S BODILY
HARM. E X E R C I S E C A R E WHEN SERVICING B R A K E
COMPONENTS. DO NOT C L E A N B R A K E COMPO­
NENTS WITH C O M P R E S S E D AIR OR B Y DRY
BRUSHING. U S E A VACUUM C L E A N E R S P E C I F I ­
C A L L Y DESIGNED FOR REMOVING B R A K E DUST.
IF A S U I T A B L E VACUUM C L E A N E R IS NOT AVAIL­
A B L E , CLEANING SHOULD B E DONE USING A WA­
T E R DAMPENED C L O T H . DO NOT C R E A T E DUST
B Y SANDING, GRINDING, OR SHAVING B R A K E LIN­
INGS U N L E S S P R O P E R L Y VENTED EQUIPMENT IS
U S E D . D I S P O S E O F A L L DUST AND DIRT THAT
MAY CONTAIN A S B E S T O S F I B E R S IN S E A L E D
B A G S OR CONTAINERS. THIS WILL MINIMIZE E X ­
P O S U R E TO Y O U R S E L F AND O T H E R S . F O L L O W
A L L RECOMMENDED P R A C T I C E S P R E S C R I B E D B Y
T H E OCCUPATIONAL S A F E T Y AND HEALTH ADMIN­
ISTRATION AND T H E ENVIRONMENTAL P R O T E C ­
TION A G E N C Y FOR T H E HANDLING, P R O C E S S I N G ,
AND DISPOSITION O F DUST OR DIRT WHICH MAY
CONTAIN A S B E S T O S F I B E R S .