Chapter 19 Parking Brake Service 333
Note: Self-contained drum brakes used on
some rear disc brake vehicles are adjusted
in the same way as conventional service
drum brakes.
Figure 19-5. Adjusting integral drum brakes using a brake tool.
In some cases, you may need to use a screwdriver to hold the
adjuster lever away from the star wheel. (Toyota)
Star wheel
Brake
adjuster
Hole in
backing plate
To bypass the switch, disconnect the switch lead and
connect a jumper wire to the lead. Ground the other end
of the jumper wire and turn the ignition switch to the on
position. If the light comes on, the switch is defective or
misadjusted. If the light does not come on, the problem is
in the bulb, fuse, or wiring.
If the proper readings are not obtained, adjust or
replace the switch as necessary. If a switch is defective, it
must be replaced.
Warning Light Always On
If the brake warning light is always on, make sure the
problem is in the parking brake switch. Many vehicles use
the same light to warn of lining wear or problems with
the hydraulic system via the pressure differential switch. If
these check ok, disconnect the switch at the parking brake.
If the light goes out, the switch is stuck or misadjusted.
Adjust or replace it as necessary. If the light stays on, there
is a short in the wiring leading to the switch.
Cables and Linkage
Operating cables and linkage should be inspected for
damage and corrosion. Check closely for frayed cables.
Any loose cable strands are cause for replacement. Look
for damaged sheaths and missing guides. Check for dam-
age at the rubber boots where the cables enter the vehicle’s
interior. Also check the cable ends, equalizer, and multi-
plier for bends and wear. If any cable pulleys are used,
make sure they turn freely and do not bind.
Adjusting Parking Brakes
If the foot or hand lever can be moved out to the limit
of its travel without effectively applying the parking brake,
the system requires adjustment. To adjust parking brakes,
begin by checking the condition of the service brakes.
Often, a loose parking brake adjustment is an indication
the service brakes are worn. If the service brakes are in
good condition, adjust them as necessary. Then adjust the
parking brake linkage.
Drum Brakes
Service of integral rear drum brake system compo-
nents was covered in Chapter 15. However, drum brakes
do require periodic adjustment as part of normal mainte-
nance and whenever the front pads are replaced.
To adjust integral drum brakes, begin by placing the
vehicle on a lift. If the vehicle is a rear-wheel drive, shift
the transmission to Neutral. Make sure the parking brake
lever is not applied. Raise the vehicle and remove the
rear wheels. Pull the drum, clean any dust, and check
the linings for wear. There should be a minimum of .059”
(1.5 mm) of lining on the shoes. Replace the linings if
they are worn.
Reinstall the drums and install 2-3 lug nuts to hold the
drum in place. Most drum brake assemblies have an access
hole, either in the backing plate or on the drum face. The
access hole is in line with the drum brake star wheel. Most
are sealed by a punched metal cover. Remove this cover
and discard. Insert a brake adjustment tool and/or standard
screwdriver, Figure 19-5. Using a lever action, rotate the
star wheel. Direction for adjustment varies by vehicle, so
check the service manual. Adjust the wheels until you feel
a light drag. Check parking brake application and adjust
the cables as needed. Make sure you install a rubber plug
in the access hole when you are completed.
Adjusting Wheel Brake Components
This section is a review of wheel brake adjustment.
Parking brake component service on the wheel brake
assemblies is covered in Chapters 13 and 15. When work-
ing on any wheel brake components, be sure to use an
approved vacuum or washer to clean parts.
Self-contained drum brakes used on rear-wheel disc
brake systems are similar to those used in integral drum
systems. The drum is part of the rotor assembly. The park-
ing brake setup shown in Figure 19-6 does not require
periodic service.
If the caliper is removed for pad replacement or other
service, it is a good idea to remove the rotor and check the
linings for wear. Shoe replacement procedures are similar
to those for integral drum brakes. The self-contained drum
brake adjuster can usually be reached through the front
of the drum and rotor assembly, Figure 19-7. Obtain the
correct manufacturers’ service manual before attempting to
adjust the brakes.