LR3 (LA) V8-4394cc 4.4L (2005)
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The brake booster is installed in the driver side of the engine compartment, on the engine bulkhead. The brake booster is a dual diaphragm unit with a
boost ratio of 7.0:1. The input push rod is connected to the brake pedal. The output push rod locates in the primary piston of the brake master cylinder.
A vacuum pipe, installed in a grommet in the front face of the housing, connects the brake booster to the intake manifold and electric vacuum pump
(petrol models) or the engine driven vacuum pump (diesel models).
Vacuum Pump (4.0L And 4.4L)
On petrol models the electric vacuum pump supplements the main vacuum supply from the engine manifold.
The vacuum pump is installed on a mounting bracket in the front left corner of the engine compartment. Two anti-vibration mounts on the vacuum
pump are located on studs on the mounting bracket and secured with nuts.
The vacuum pump consists of a radial vane pump driven by an electric motor. The rotor and vanes of the pump are made from a self-lubricating
carbon based material. A stub pipe is installed in the inlet of the pump to provide a connection point for the vacuum pipe from the brake booster. A
second stub pipe, which is covered by a rubber shroud, is installed in the outlet from the pump.
Operation of the vacuum pump is controlled by the Engine Control Module (ECM), which uses the brake vacuum pump relay in the Battery Junction
Box (BJB) to switch power to the vacuum pump. The ECM controls the time for which the vacuum pump is switched on and has in-built safeguards to
protect the pump from overuse, e.g. continuous running is not allowed so a minimum delay time is specified between applications.
Vacuum Pump Control Diagram (4.0L AND 4.4L)
