Hydraulic Unit and Brake Booster/Master Cylinder Assembly Overview, Mark 25, through 24 November 2006
1 Anti-lock Brake System (ABS) Control Module (w/Electronic Differential Lock (EDL)) (J104)
2 ABS Hydraulic Unit (N55)
3 Brake Line
• Master cylinder/primary piston circuit to hydraulic control unit.
• Identification at hydraulic unit - DK -.
4 Brake Line
• Master cylinder/secondary piston circuit to hydraulic unit.
• Identification at hydraulic unit - SK -.
5 Brake Line
• Via the intermediate piece to the left rear brake caliper.
• Identification at hydraulic unit - HL -.
6 Brake Line
• Via the intermediate piece to the right front brake caliper.
• Identification at hydraulic unit - VR -.
7 Brake Line
• To the left front brake caliper.
• Identification at hydraulic unit - VL -.
8 Brake Line
• Via the intermediate piece to the right rear brake caliper.
• Identification at hydraulic unit - HR -.
9 Intermediate Piece
10 Bracket
• Allocation, refer to the parts catalog.
11 Hex Flange Bolt
• 5 Nm
12 Bolt
• 8 Nm
13 Buffer
14 Gasket
• For the brake booster.
15 Brake Booster
• Includes the brake pressure release solenoid (F84) and brake pressure magnetic coil (N247) (not interchangeable)
• On gas engines, vacuum is supplied from the intake manifold.
• Vehicles with a gas engine and automatic transmission are equipped with a brake system vacuum pump.
• On diesel engines, a vacuum pump is installed for vacuum creation.
• Function test:
- With the engine turned off, press the brake pedal firmly several times (to exhaust the vacuum in the unit).
- Press and hold the brake pedal with average foot pressure and start the engine. If the brake booster is working properly, the pedal will be felt to give noticeably under foot (booster assistance becomes effective).
• Replace as a unit in the event of malfunction (previously, check all vacuum lines).
• Removing and installing, refer to => [ Brake Booster ] Brake Booster.
16 Seal
17 Brake Booster Membrane Position Sensor (G420)
• Removing and installing, refer to => [ Brake Booster Membrane Position Sensor ] Service and Repair.
• Discontinued from calendar week 27.11.06.
18 Snap Ring
19 Sealing Plugs
• Connection for vacuum hose.
20 Vacuum Hose
• Insert into the brake booster.
21 Seal
22 Self Locking Nut
• 25 Nm
• Always replace after removal.
23 Brake Pressure Sensor (G201)
• Removing and installing, refer to => [ Brake Pressure Sensor 1 ] Service and Repair.
• In the Electronic Stabilization Program (ESP) unit from calendar week 27.11.06.
24 Bracket
25 Master Cylinder
• Cannot be serviced. Replace as a complete unit if malfunctioning.
• Removing and installing, refer to => [ Brake Master Cylinder ] Service and Repair.
26 Sealing Plugs
• Lubricate with brake fluid and press into the brake fluid reservoir.
27 Brake Fluid Reservoir
28 Cap
29 TORX Bolt
• 4 Nm
Brake Lines from Master Cylinder, Connecting to Hydraulic Unit
On the Master Cylinder:
On the Hydraulic Unit:
A Hydraulic unit to primary piston circuit of master cylinder
Identification at hydraulic unit - DK -
B Hydraulic unit to secondary piston circuit of master cylinder
Identification at hydraulic unit - SK -
1 Hydraulic unit to left front brake caliper
Identification at hydraulic unit - VL -
2 Hydraulic unit via the intermediate piece to the right front brake caliper
Identification at hydraulic unit - VR -
3 Hydraulic unit via the intermediate piece to the right rear brake caliper
Identification at hydraulic unit - HR -
4 Hydraulic unit via the intermediate piece to the left rear brake caliper
Identification at hydraulic unit - HL -