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REPAIR MAINTENANCE OPERATION OF MOTOR VEHICLES
Mercedes-Benz C-Class (W203, 2000 issue)

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Mercedes-Benz W203
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W203
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Brakes
Specifications
Replacement pads front disc brakes
Removal and installation of a forward support
Replacing the rear brake pads
Removing and installing rear brake caliper
Removal and installation of a brake disk
Check brake disc
Dual brake master cylinder
Replacing brake pads handbrake
Removal and installation of the parking brake cable
Removing and installing brake light switch
Removal of air from brake system
Removal and installation of a brake hose
Checking the brake booster
Suspension and steering
Body
Onboard electric
 


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Brakes



Hydraulic brake components and auxiliary systems BAS and ESP

1 - Turbofan GTZ
5a - brake caliper front right wheel
5b - brake caliper left front wheel
6a - brake caliper right rear wheel
6b - brake caliper left rear wheel
A7 / 7 - Brake Assist (BAS)
b1 - BAS diaphragm travel sensor
s1 - sensor switch is released, BAS
y1 - The solenoid valve BAS
N47-5 - Control unit ESP / BAS
S11 - Sensor switch brake fluid

Driving hydraulic circuit protivozanosnoy ESP system

7 - Check valve
9 - the one-way check valve recirculation pump
11 - Low-pressure accumulator
12 - Shock to the control plate
13 - The diaphragm pulsation dampener
14 - Barochuvstvitelnaya control plate
A7 / 3 - hydromodulator auxiliary brake systems
m1 - Naporno-return pump
p1 - Self priming pump front loop
p2 - Self priming pump rear contour
y6 - left front solenoid valve, pressure maintenance
y7 - left front solenoid valve, pressure relief
y8 - Right front solenoid valve, pressure maintenance
y9 - Right front solenoid valve, pressure relief
y10 - left rear solenoid valve, pressure maintenance
y11 - left rear solenoid valve, pressure relief
y12 - rear right solenoid valve, pressure maintenance
y13 - rear right solenoid valve, pressure relief
y18 - Managing the front solenoid valve circuit
y19 - control solenoid valve rear circuit
y22 - front suction solenoid valve circuit
y23 - suction solenoid valve rear circuit
B34 - The brake pressure sensor ESP (models of release since 08/01)
B34 / 1 - 1 pressure sensor ESP (not installed on models 08/01)
B34 / 2 - Sensor 2 pressure ESP (not installed on models 08/01)
VA - The contour of the front axle
HA - The contour of the rear axle
VL - the front left wheel brake
VR - front right wheel brake
HL - Brake rear left wheel
HR - rear right wheel brake

Electrical controls braking and auxiliary systems BAS and ESP

A1 - Dashboard
e7 - Control lamp of brake fluid level and the parking brake charging
e17 - ABS warning lamp
e41 - ESP warning lamp
p13 - Multifunction display
A7 / 3 - hydromodulator auxiliary brake systems
A7 / 7 - Brake Assist (BAS)
b1 - BAS diaphragm travel sensor
s1 - sensor switch is released, BAS
y1 - The solenoid valve BAS
B24 / 2 - Sensor transverse accelerations
B34 / 1 - 1 The brake pressure sensor ESP
B34 / 2 - 2 brake pressure sensor ESP
L6 / 1 - speed sensor Left Front Wheel
L6 / 2 - Speed sensor front right wheel
L6 / 3 - Speed sensor rear left wheel
L6 / 4 - Speed sensor rear right wheel
N10 / 1 - Front SAM control unit with fuse and relay box
N10 / 2 - SAM control unit with the rear fuse box and relays
N47-5 - Control unit ESP / BAS
N49 - angle sensor
N64 - yaw rate sensor
N72 / 1 - The control unit is the top of the control panel
s1 - sensor switch off ESP (ESP OFF)
S9 / 1 - The gauge-switch of stoplights
S10 / 1 - contact sensor brake pad left front wheel
S10 / 2 - contact sensor pads brake right front wheel
S10 / 3 - contact sensor pads brake left rear wheel
S10 / 4 - contact sensor brake pads right rear wheel
S11 - Sensor switch brake fluid
S12 - Sensor switch charging the parking brake

The construction of a capacitive sensor rotation and acceleration of the body of the ESP

and - Silicon ring
b - Spring Jumper
c - electronic sensor

Location rotation sensor and body acceleration protivozanosnoy ESP system

The functioning of the capacitive sensor and the steepness of the rotation acceleration of the body of the ESP


The hydraulic brake system consists of a master cylinder, brake booster, unit ABS and disc brakes front and rear wheels. The hydraulic brake system is divided into two circuits. One circuit acts on the front brake, the second path - the rear wheels. When one of the circuits, for example, due to leakage of the fluid, braking the car by another circuit. The fluid pressure in both circuits created twin master cylinder acting on the brake pedal.

The tank with a brake liquid is located in the engine compartment on the driver side under the cover of the master cylinder. It supplies the whole system with brake fluid. The volume of liquid in the tank must be constantly monitored.

Job Description anti-lock braking system ABS, BAS brake assist and electronic stability program stability (protivozanosnoy system), see "Controls and receptions of safe operation."

The front brakes are floating caliper bracket. Such a construction for driving both brake pads requires only one piston. The rear brakes have a fixed caliper.

Power brakes accumulates part of the vacuum created in the intake manifold of the engine. Since the diesel engine is not required vacuum suction, diesel engine vehicles have a special vacuum pump is installed in front, on the cylinder head, and is driven by a camshaft.

Using an appropriate valve, the force from the brake pedal increases under vacuum.

Foot parking brake operates through cables to the brakes the rear wheels. On the rear wheels additionally installed drum brakes, built-in disc brakes. Drum brakes are activated only on pedal parking brake. Brake pads rear wheels are set automatically, requiring only rarely adjust the parking brake, for example after the repair.

Features auxiliary systems ABS, ESP and BAS

The functioning of the auxiliary hydraulic circuit brake system
The structure hydromodulator auxiliary braking systems (A7 / 3) includes components of the closed loop system dynamic control systems ABS, ASR and ESP.

Pressure and return pump (A7 / 3m1)

Self priming discharge and return pumps (p1, p2) are integrated into an assembly hydromodulator (A7 / 3) and are switched in the phases of pulse signals pressurizing and depressurizing active control system ASR and ESP, and during adjustment backflow ABS activation.

Solenoid valves and maintain pressure relief (A7 / 3y6-y13)
A 2/2-way valve is used for pressure control in circuits of each of the wheels in the phases of the injection / hold and hold / reset control mode, ABS, ASR and ESP.

Low-pressure reservoir (11)

Low-pressure reservoir (11) is filled with brake fluid phase pressure relief ABS, ASR and ESP and ensures its transmission to the pressure-return pumps (p1 / p2).

Control solenoid valve circuit (A7 / 3y18 and y19)

Solenoid valves Switches (y18 and y19) provides active pressure cutoff circuits front and rear axles of the GTZ in the functioning of ASR and ESP. Also provide pressure relief valves when lifting it above 150 atm. Passed through a switching valve brake fluid is sent back to the GTZ.

Suction solenoid valves (A7 / 3y22 and y23)

Inlet solenoid valves (y22, y23) opened in phases pressure build ASR / ESP.

Brake pressure sensor (B34, B34 / 1, B34 / 2)

ESP Mk20 (models up to 1.7) is equipped with two brake pressure sensors. Probe 1 (B34 / 1) monitors the pressure in the front brake circuit, a sensor 2 (B34 / 2) - in the rear.

The ESP Mk25 (model 8/01) is only one sensor (B34), which monitors the pressure in the front loop.

Emitted by the sensor information is transmitted to the control unit and is used in the calculation of the parameters of a closed control loop.

Reduced background noise

Self-priming return pump and pressure (p1, p2) run as necessary to minimize the noise level.

Various damping components (13, 14) provide a further repayment of noise. Each brake circuit is equipped with a separate damper (12), reduces the level of noise produced by the pump.

Sensor slope rotation and acceleration of body

Sensors that monitor the angular velocities and transverse overloading combined into an assembly slope rotation and lateral accelerations (B24 / 5), which saves space they. Micromechanical sensor assembly converts the lateral and vertical projection of the angular accelerations into electrical signals. Various mass elements under the action occurring during irregular motion of the vehicle (acceleration and cornering) overloads provide varying degrees of deformation. Special electronic converter converts the received signals and transmits them via CAN bus to the control unit and protivozanosnoy traction systems (N47).

The principle of operation of the sensor

The sensing element is formed of a micromechanical ring (a), equipped with eight spring webs (b), providing its movement and Electromagnetic action. Upon rotation of the assembly have additional Coriolis force proportional to the speed of rotation and electromagnetically latched after conversion module ACIS in the form of analog signals issued by the control unit of the dashboard.

The measuring principle is based on the transverse accelerations using spring-mass element with a capacitive detector. Operating voltage is supplied to the control unit ESP (N47-5).

Emerging at the time of cornering transverse loads provide a displacement of the spring-mass element from its equilibrium position by an amount proportional to the value an overload. Any change in the position of the element leads to a change in the capacitance detector. Next, a deviation is converted into a voltage signal, which allows the control unit ESP (N47-5) quantify the values recorded by the transverse loads.

The electronic control unit ensures that the system, when it is damaged (eg broken cable), or by reducing the voltage itself off. The situation is displayed on the instrument panel lighting of control lamp ABS orange. At the same time switched off the ESP and BAS, which is indicated by lighting up of the indicator ESP. The main brake system maintains its efficiency at the same time. During braking the car behaves as if no ABS system.

If, for example, while moving the control lamp ESP, this indicates a malfunction of the amplifier or protivozanosnoy braking system. BAS and ESP are deactivated. Normal system while maintaining its efficiency.

If during movement the control lamp lights red (symbol: call sign) braking system, you must stop immediately and determine the cause. Reasons may be insufficient amount of brake fluid or a cocked parking brake.

If during movement control lamp ABS:

1. Stop the car, stop the engine and restart it.
2. Check the battery voltage. If the voltage is less than 10.5 V, charge the battery.

If the ABS warning lamp lights up at the beginning of the motion, and then some time later extinguished, it indicates a low battery voltage, which increases after the start of operation of the generator.


3. Check whether firmly fixed terminals of the battery.
4. Put the car on supports, remove wheels and check the electrical wires to the wheel speed sensor for external damage. Other inspections are to be carried out in conditions HUNDRED. Electronics has self-diagnostics available faults are recorded automatically by the system. Checking records and fault produced in the workshop.

Before performing welding operations necessary to disunite connector ABS. The compound is located in the engine compartment, at the top, the driver's side, behind a removable cover. Connection undocks only when the ignition is off. When the paint is not allowed to heat the work control unit to a temperature above + 90 ? C.

When cleaning brake dust is released that can be harmful to human health, so it is impossible to inhale brake dust.

Work on the brake system requires a high purity and precision of instructions. In the absence of the necessary experience it is advisable to contact the service station.


When driving on wet roads need to periodically press the brake pedal to remove moisture from the brake discs.


During wheel rotation moisture centrifugally discharged from the brake disc, but there is a film of silicone rubber attrition, grease and other impurities that reduce the effectiveness of the brakes.

After installing new brake pads should last run-in. Therefore, the first 200 kilometers are not unnecessarily very slow.

Disc brakes with corrosion under braking give the effect of shaking, do not disappear with time. In this case, replace the brake discs.

Dirt sticking to the surface of the brake pad and rain grooves lead to formation of grooves on the surface of the brake disk, leading to a decrease in braking efficiency.




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