Power Brakes - DaimlerChrysler LH New Yorker 1994 Electronic Service Manual

5 - 72 BRAKES
GENERAL INFORMATION
The purpose of the vacuum operated power brake
booster. Is to reduce the amount of force applied to
the brake pedal by the drivers foot. To obtain the
required hydraulic pressure in the brake system to
stop the vehicle.
The power brake booster can be identified if re-
quired, by the tag attached to the body of the booster
assembly (Fig. 1). This tag contains the following
information. The production part number of the
power booster assembly, the date it was built and who
manufactured it.
The power brake booster assembly is not a
repairable part and must be replaced as a com-
plete unit if it is found to be faulty in any way.
The power booster vacuum check valve is not
repairable but can be replaced as an assembly.
Fig. 1 Power Brake Booster Identification
The power brake booster in vacuum operated. The
vacuum is supplied from the intake manifold on the
engine through the power brake booster check valve
(Fig. 1).
As the brake pedal is depressed, the power boost-
ers input rod moves forward. This opens and closes
valves in the power booster, creating a vacuum on
one side of a diaphragm and allowing atmospheric
pressure to enter on the other. This difference in
pressure forces the output rod of the power booster
out against the primary piston of the master cylin-
der. As the pistons in the master cylinder move
forward this creates the hydraulic pressure in the
brake system.

POWER BRAKES

Fig. 2 Power Brake Booster Assembly
Different systems and engine combinations require
different vacuum hose routings.
The power brake booster assembly mounts on the
engine side of the dash panel. It is externally con-
nected to the brake system by an input push rod to
the brake pedal. A vacuum line connects the power
booster to the intake manifold. The master cylinder is
bolted to the front of the power brake booster assem-
bly.
SERVICE PROCEDURES
POWER BRAKE BOOSTER ASSEMBLY
REMOVE
(1) Remove both wiper arm assemblies.
(2) Remove cowl panel cover from cowl to expose
windshield wiper module.
(3) Remove the 5 screws attaching the windshield
wiper module to the dash panel. Remove the wind-
shield wiper module from dash panel.
(4) Remove the 2 nuts (Fig. 3) attaching master
cylinder assembly to power brake unit.
(5) Carefully slide master cylinder off mounting
studs with brake lines attached, and allow the assem-
bly to rest against left shock tower.
(6) Disconnect vacuum hose from power brake
booster check valve (Fig. 1). DO NOT REMOVE
CHECK
BOOSTER.
VALVE FROM POWER BRAKE