Mercedes S-class W202

1993-2000 of release

Repair and car operation

Mercedes W202
+ 1.2. The general data
+ 2. Maintenance service
+ 3. Engines
+ 4. Greasing system
+ 5. Cooling system
+ 6. Heating, ventilation
+ 7. Ignition system
+ 8. Fuel system
+ 9. Transmission
+ 10. A running gear
+ 11. A steering
+ 12. Brake system
+ 13. A body
- 14. An electric equipment
   14.1.2. Measuring devices
   14.1.3. Technics of measurements
   14.1.4. Electric equipment checks
   14.1.5. A sound signal
   14.1.6. Replacements of safety locks
   + 14.1.7. The storage battery
   + 14.1.8. The generator
   + 14.1.9. A starter
   14.1.10. The traction relay
   + 14.1.11. Illumination system
   14.1.12. Devices
   14.1.13. The instrument panel
   14.1.14. Lamps накаливания on the panel of devices
   14.1.15. Light switch
   14.1.16. A radio receiver
   + 14.1.17. The aerial
   14.1.18. Dynamics
   + 14.1.19. Rubber brushes of screen wipers
   14.1.20. Jets стеклоомывателя
   14.1.21. Washing atomizers of headlights
   14.1.22. A screen wiper and its engine
   14.1.23. Protect the car
   14.1.24. Anticreeping "immunodeficiency"
   14.1.25. Why headlights grow dull
   14.1.26. "Галогенки"
+ 14.2. Electroschemes

14.1.4. Electric equipment checks

At search of malfunctions in an electric equipment the system approach is important. It is fair both at check of the failed lamps накаливания, and in case of idle electric motors.

The first step always is safety lock check as it protects an electric element of a design. The actual arrangement of safety locks can be seen on напечатке, being on a cover of the block of safety locks.

If necessary replace a faulty safety lock and after connection of the electric consumer check up, whether it has fused again. In this case first of all it is necessary to find out malfunction and to eliminate it, here, as a rule, it is a question of short circuit.

The second control step: If at a serviceable safety lock the lamp накаливания is not shone, or the electric motor it is necessary to check up power supplies system, accordingly, does not work.

Lamp check накаливания

Take and examine a lamp. If has fused an incandescent filament or a glass cylinder расслабленно sits in a socle it is necessary to replace a lamp.

To define, whether the lamp накаливания is serviceable, arrive as follows:

Connect directly to poles of the storage battery a positive wire (+) and earthing (on the car case) a wire (–) and connect them to a lamp. Thus it is not important, what wires are connected to a lamp. One wire attach to токопроводу, another – to the lamp case накаливания. If and now the lamp is not shone, replace it.

It is necessary to be assured that contacts on a lamp and a lamp cartridge are not covered by corrosion. If necessary correlated or bent conclusions smooth out a grinding skin and make normal contact.

If the lamp is serviceable, insert it and include. If the lamp is not shone, by means of a control bulb check up power supplies giving. For this purpose connect a control bulb to weight of the car. Т е., one wire of a control bulb should be connected to a good point of the case on the engine (the polished metal) or is direct to a negative pole of the storage battery. Another щуп a control bulb (+) hold or on current carrying штеккере, or connect it to a wire which is energised. If now the control bulb lights up, and the lamp nevertheless does not burn, the line connecting the case of the car with a lamp накаливания is broken off. That it to check up, put to a lamp cartridge the auxiliary wire connected to the case of the car. Now the lamp накаливания should light up.

Instructions: there are lamps which are equipped only by one feeding line being energised, for example, lay fire, internal illumination of the car. These lamps by means of the case are directly connected with weight of a vehicle.

If in a current carrying wire to a lamp there is no pressure and the control bulb it is very probable that the switch is faulty is not shone. Check up the switch on current passage.

Check of electric motors

In the car escalating comfortableness is provided with low-power electric motors. The moved panel of a roof, system of locks of doors concern them with the central management or the electric aerial, for example, стеклоподъемник. At need each electric motor joins by means of one switch usually manually. In case of the electric aerial the switch automatically copes through a radio receiver.

Check up resistance of the corresponding electric motor, if necessary replace it.

The prevention

Before new actuating eliminate the reason of an overload electric стеклоподъемника and systems of locks with the central management. It can be, for example, the chilled glasses and locks or the polluted fillets of lowered glass.

If the safety lock again fuses at once, it testifies to short circuit presence.

Unequivocally to find out, whether there is a malfunction in the engine, lay two auxiliary wires in diameter about 2 mm directly from the storage battery of the car to the electric motor. Connect a positive wire to a positive pole, and, the wire connected to the case, to an earthing pole. In case of doubt distribution of poles is defined from the basic scheme of an electric equipment. If it is necessary, for this purpose it is necessary to disassemble the electric motor. All electric motors in the car запитываются onboard pressure (from 12 to 14 Volt). If now the electric motor works normally, power supplies system was faulty.

The prevention

Cлишком electric motor slowly rotating or working with faults can mean that sliding electrographite contacts are worn out. In that case replace these contacts.

If the engine works, under the electric equipment scheme establish, what feeding wire brings pressure to the electric motor when the switch is put in action at earlier included ignition.

By means of a control bulb check up a wire being energised in the electric motor. As in electric motors the big current it is possible to replace a usual control bulb with a lamp накаливания proceeds. These lamps are equipped by peaked test needles with which help it is possible to pierce a connecting wire. In such simple way it is possible to check up pressure. Engines which alternately rotate to the left / to the right, for example, engines стеклоподъемников, have two плюсовых a conclusion.

The prevention

Check up the screen wiper engine.

If on the electric motor pressure power supplies system is faulty does not arrive; find defect in a bringing line under the basic scheme of an electric equipment and eliminate it. As a rule, because of high consumption of a current, electric motors have the additional switching relay.

If malfunction is not found out, check up the switch.

If the wire frequently it is more rational to lay a new wire as under isolation the rupture place is difficult to define is damaged.

Check of switches on current passage

The majority of electric consumers join and switched off with the help of manually pressed switch. Besides, there are switches, with an automatic drive. Such switches concern, for example, the switch with a hydrodrive (the pressure drop gauge in brake system) and the gauge of level of a brake liquid.

Basically, the switch has the task to close or break off an electric chain. There are switches which break off an earthing line, and switches which break off a line of a positive pole.

Check of switches of lamps and electric motors

Remove the corresponding switch.

Simple switches have only two conclusions for wire connection. In this case on one conclusion pressure (+), and after deenergizing inclusion / – and on other conclusion should arrive . There are switches with several plugs. At these switches on the basis of the basic scheme it is explained, pressure should be applied on what plug. If necessary in advance include ignition.

Check up by means of a control bulb, whether pressure on the switch arrives. If the control bulb lights up, include the switch and check up, whether pressure arrives on the target plug also. If it so it is established that the switch functions.

If on the target plug there is no pressure it means that in a wire of giving of power supplies there is a rupture. On the basis of the basic scheme of an electric equipment check up a supply of pressure and, if necessary, lay a new wire.

Check of switches-gauges

Switches-gauges, for example, are the switch with a hydrodrive, gauges of level of a brake and cooling liquid.

Connect a sampler (a control lamp or an ohmmeter) to a bringing and taking away wire of the switch, for this purpose remove a wire from the switch.

The prevention

Switches which are screwed in in the block of cylinders of the engine, do not have, as a rule, the wire connecting them with the case as the switch case on top of the block of cylinders of the engine serves as an earthing pole.

The included switch the sampler should display "current passage". The best sampler is the ohmmeter: at the included switch it shows zero the Ohm, and at switched off – infinity.

Fastest approximately it is possible to check up precautionary switches of level of a cooling and brake liquid, delaying at the included ignition bringing wire from the switch and pressing it to well earthed place, for example, to the block of cylinders of the engine. If the alarm bulb on the panel of devices malfunction is in the switch works. The special case represents the switch with a hydrodrive (the power failure gauge in brake system): at a stop of the engine contact will close (the alarm bulb burns), the switch is disconnected only at certain pressure of oil.

Relay check

In many electric chains the relay is established. The switching relay works as the switch. An example: if the headlight of headlights by means of the manual switch the relay receives a command joins to switch a current to a headlight of headlights. Certainly, it would be possible a current and directly a tax from the storage battery, by means of light switch. But at all elements with high consumption of a current (a headlight headlight, a screen wiper, an antifog headlight) in a chain it is connected the relay not to overload the switch, providing more short ways of passage of a current, Near to these combinational relays functional relays, for example, for systems стеклоочищения and стеклоомывания or the precautionary sound relay for the included external illumination are located also.

Check of the switching relay

At inclusion of a lighting element the relay is started, i.e. by means of a switching current the electromagnetic coil involves inside contact of the relay and thus closes an electric chain of "a working current". The working current through the relay arrives further to the consumer. Is most easier working capacity of the relay can be checked up, having replaced its serviceable. So arrive even in a repair truck. As the owner of the car seldom has at once on hand a new relay in such cases it is recommended to perform the following operation in case of so-called, switching relays which are applied, including, to inclusion of antifog and basic headlights. The marks of plugs specified here, first of all, at serially established relays, can be presented and in another way.

Get the relay from the holder.

Include ignition and the corresponding switch.

At first establish by means of the pressure indicator, whether pressure on the plug 30 (+) in the holder of the relay arrives. For this purpose connect the pressure indicator to the case (–), and other contact cautiously enter into the plug 30. If flashes светоизлучающий the diode pressure is. If the indicator of pressure does not show pressure under the basic electroscheme find breakage of the wire going from a positive pole of the storage battery (+) to the plug 30.

Make of a piece of the isolated wire a current-carrying crosspiece, having smoothed out it to shine.

By means of this crosspiece in the holder of the relay connect the plug 30 (+ the storage battery always is energised) to an exit of closing contact on the plug 87. By means of this working operation the same is practically carried out, as at installation of the serviceable relay.

If with a crosspiece the headlight it is possible to consider, for example, lights up that the relay is faulty

If the headlight does not light up, find out, whether connection on the case at headlights is perfectly in order. In this case find and eliminate rupture in a line from the plug 87 to the basic headlight, using the scheme of connections. If it is required, establish the new relay.

The prevention

If defect in an electric chain which is equipped by one relay, is shown only periodically in this case, as a rule, malfunction is concluded in the relay: contact in the relay or contact too залипает while in the relay rest of the time functions normally vanishes. At defect display slightly knock on the relay case. If and after that the relay is switched, replace it.

Check of the engine of a screen wiper

The screen wiper engine is established in a catchment basin, under a windscreen. For check it is necessary to remove a corresponding casing.

Marks of plugs

Plugs on the engine are standardly designated as follows:

 – The plug 31 is a plug for connection with the case (in general in an electric equipment of vehicles);
 – The plug 53 – receives pressure for the first speed of a screen wiper;
 – The plug 53а – delivers a positive current (+) for installation in a starting position of brushes of a screen wiper: the engine receives until then pressure through sliding contact while screen wipers work in a starting position if the driver switches off screen wipers;
 – The plug 53в – submits pressure for the second speed of a screen wiper (a parallel winding);
 – By means of the plug 53е the screen wiper engine is braked at movement back after switching-off that screen wipers did not leave the stopping position;
 – The plug 53с (from the relay) – submits pressure on the electric pump of a screen wiper.

Check of the engine of a screen wiper

To begin with find out, whether the engine of a screen wiper is serviceable and whether the electromaintenance system is perfectly in order. For finding-out of it arrive as follows:

 – Disconnect from the screen wiper engine multicontact штеккерный a socket;
 – By means of two auxiliary wires submit pressure (+) and weight (–) from the storage battery on the screen wiper engine;
 – One wire lay from a positive pole of the storage battery to the plug 53 or 53в;
 – The second wire spend from a negative pole of the storage battery to the plug 31 engines;
 – Now depending on the used plug the engine should work at a step I or II. If the engine does not work, it is faulty or its corresponding step. Remove the screen wiper engine.

Check of the device of blinking light signals

Steps for the device of blinking light signals and system of the emergency light alarm system are developed the relay, the so-called gauge of flashing light signals. The system of the emergency light alarm system is connected to the relay without a safety lock. The system of instructions of turns is protected by the safety lock which is in the block of safety locks.

If the rhythm of the blinking device faster on one party, than on another on "the fast" party the lamp накаливания is faulty or is available chain breakage.

At occurrence of other defects in most cases the reason is the breaker of indexes of turns (the gauge of flashing light signals).

On the breaker of indexes of turn following positions of plugs are specified:

 – The plug 31 is weight of the car (a minus in an electric equipment of all vehicles);
 – The plug 49 – a relay input (constantly moves плюсовое pressure);
 – The plug 49а – a relay exit;
 – The plug With conducts to a control bulb on the instrument panel, in the presence of the towing device there can be additional plug S2 for the alarm system of inclusion of indexes of turn of the trailer.

If you do not have new relay cautiously insert a thin wire between plugs 49 and 49а in relay штеккерном a socket.

The prevention

Thus do not damage sensitive relay contacts. Before insertion bend the wire ends that there were no keen edges. Again spread the faulty breaker of indexes of turn. Extend so connecting шинки that it was possible to spread again the breaker, despite shunting.

Include ignition. If in action the lever of indexes of turn long time is shone the corresponding party of the device of blinking light signals now is put. By means of inclusion and deenergizing of this device it is possible to generate a blinking rhythm.

If, despite shunting, blinking fire the switch of indexes of turn in an electric bringing line is faulty is not shone.

Check of a signal of braking

If the braking signal, first of all, check up a safety lock in the block of safety locks is not shone.

If the safety lock is perfectly in order, check up lamps накаливания a braking signal, if necessary replace fused lamps.

If lamps накаливания are serviceable, check up the switch of a signal of braking which is established from above brake pedals on its rack. At нажимании on a pedal of a brake press the pin is pulled out from the switch. Contact of the switch becomes isolated and the braking signal lights up.

Check up the switch of a signal of braking. For this purpose remove a protective casing from above pedals. Remove a tip of wires from the switch of a signal of braking.

Switch off ignition.

Зашунтируйте both contacts in a tip of wires of the switch of a signal of braking by a short auxiliary wire. If braking signals the switch of a signal of braking is faulty now light up and it is necessary to replace it.

Check of a heater of back glass

At inclusion of a heating system of back glass after some time the area with visible paths should be released from a touch or ice.

At malfunctions at first check up a safety lock in the block of safety locks.

If the safety lock is serviceable, check up rigid landing of a tip of wires by its turn to the left and to the right on back glass, if necessary clear it of corrosion products.

If nevertheless the heating system of back glass does not function, check up integrity of bringing wires and working capacity of the switch, and also the switching relay.

If heating lines for restoration of their connection the current-carrying silver varnish helps are broken off. For this purpose clear the damaged zone a thinner or ethyl spirit.

The broken off place from both parties paste over with a sticky tape and put a small brush a silver varnish.

Leave a varnish to dry at temperature about +25 degrees during 24 ч. It is possible to warm up its hot air. At temperature 130 About a varnish dries up approximately for 30 minutes.

The prevention

Do not include a heating system of back glass while the varnish will not dry up completely. To clearing of the damaged part do not apply gasoline or other solvent.