The general information on search of malfunctions in electric chains. BMW the 5th E28/E34 series (from 1981 to 1993 of release)
Repair of BMW E28 and series E34 from 1981 to 1993
1. Cars of the BMW brand of 5-series
2. Engine
3. Cooling system
4. Power supply system
5. Ignition system
6. Control systems of the engine and decrease in toxicity of the fulfilled gases
7. System of production of the fulfilled gases
8. Coupling
9. Manual box of gear shifting (RKPP) and automatic transmission (AT)
10. Transmission line
11. Steering and suspension bracket
12. Brake system
13. Body
14. Control body sizes
15. Heater and air conditioner
16. System of onboard electric equipment
16.1. General information
16.2. The general information on search of malfunctions in electric chains
16.3. Removal and installation of the storage battery
16.4. Check of a condition and replacement of wires of the battery
16.5. General information on safety locks
16.6. General information on the relay
16.7. General information about charge and precautionary measure system at work with it
16.8. Check of system of a charge
16.9. Removal and generator installation
16.10. Replacement of a regulator of tension
16.11. Check and replacement of brushes of the generator
16.12. General information about system of start of the engine and a precautionary measure
16.13. Starter check on the car
16.14. Removal and starter installation
16.15. Removal and installation of the traction relay
16.16. Check and replacement of breakers of indexes of turn and alarm system
16.17. Removal and installation of switches on a steering column
16.18. Removal and installation of the lock of ignition
16.19. Removal and radio receiver installation
16.20. Removal and aerial installation
16.21. Removal and installation of components of an instrument guard
16.22. General information on the panel of alarm lamps of a reminder on term of service (SI)
16.23. Replacement of lamps in head headlights
16.24. Adjustment of a beam of head headlights
16.25. Removal and installation of the case of a head headlight
16.26. Replacement of lamps
16.27. Removal and installation of the motor of a screen wiper of windscreen / glass of a door of a back
16.28. Check of work and repair of a heater of back glass
16.29. General information on auxiliary system of safety (SRS)
16.30. Description and check of work of a control system by speed (темпостата)
16.31. Description and check of work of system of the central blocking of doors
16.32. Description and check of work of system of electric window regulators
16.33. Diagnostics of malfunctions of a suspension bracket of back wheels
17. Routine maintenance of the car
18. Size table and adjusting data
19. Schematic electric circuits
20. Governing bodies and operation receptions
21. System of onboard diagnostics - a principle of functioning and codes of malfunctions


16.2. The general information on search of malfunctions in electric chains

The typical electric chain consists of an electric component, switches, the relay, motors, safety locks, fusible inserts or the breakers of a chain connected to this component, and also conducting and sockets which connect a component with the battery and the chassis. To help you to reveal malfunction in an electric chain, at the end of this Management there are Schematic electric circuits.

Before undertaking any faulty electric chain, at first study its assembly diagram completely to understand, of what it consists. For example, sometimes it is possible to narrow essentially troubleshooting area, having checked work of other components connected with this chain. If some components or chains, that failed at once, it is possible that a problem in safety locks or in grounding since often some chains pass through one connection of safety locks and grounding wires.

Malfunctions in electric chains usually occur from the simple reasons, such as easing or oxidation of the contacts, the burned-down safety lock, the melted fusible insert or malfunction of the relay. Therefore before to begin search of damages, visually check a condition of all safety locks, wires and contacts in a faulty chain.

The main devices necessary for detection of malfunction in an electric chain, include a tester, the digital voltmeter with high resistance, a tester of conductivity of a chain and a wire from a set for car start from an external source with the built-in breaker of a chain which is used for round of components of a chain. Before trying to reveal malfunction by means of testing devices, glance in assembly diagram to define, in what place them to connect.

Tension check in a chain

Check of tension is carried out when the chain badly functions. Connect one end of a tester of a chain to a negative wire of the battery or to reliable grounding.

Connect other end to one of sockets of a tested chain, it is preferable to what is closest to the battery or to a safety lock. If the bulb of a tester burns, means, in a chain there is a tension that, in turn, means that on a chain site between the socket and the battery of malfunction is not present. Continue to check the remained sites of a chain in the same way.

When you will reach a site in which there is no tension, will find a malfunction place. More often the problem appears in bad contact.

Remember that in some chains tension arises, only when ignition is included.

Finding of malfunction in a chain - quite simple business if you remember that any electric chain is the electricity going from the battery on wires through switches, the relay, safety locks and fusible inserts to various components of an electric chain (to bulbs, motors etc.) and to the earth from which it passes back to the battery. And any malfunction in a chain is a violation of a stream of an electricity from the battery or to the battery.

Search of a place of short circuit

One of methods of search of a place of short circuit in a chain is to disconnect a safety lock and to connect on its place a test bulb or the voltmeter. In a chain there should not be a tension. Move electroconducting here and there, watching a test bulb. If the bulb joins, means, on this site there is a short circuit on the earth, possibly, isolation somewhere was wiped. As each component of a chain is checked, up to the switch.

Grounding check

Carry out the test for grounding to check, whether the chain component is correctly earthed. Disconnect the battery and connect one end of a tester of conductivity of a chain to reliable grounding. Connect other end to a wire or the socket of checked grounding. If the bulb lights up, grounding is made correctly. If does not light up, it is wrong. In this case disconnect the socket and carefully clean all connecting details. Again connecting the socket, use whenever possible jagged washers and reliably tighten all bolts and other fixture.

If the radio receiver on your car is equipped with system of protection against theft, make sure that you gathered the correct code before disconnecting a battery wire. Apply for information in the Section System of protection of an audiosystem from theft and language of an instrument guard before a wire detachment.

If after wire accession on your instrument guard there were inscriptions not in that language which is necessary to you, address to the Section System of protection of an audiosystem from theft and language of an instrument guard where procedure of installation of the necessary language is described.

Check of conductivity of a chain

Check of conductivity of a chain is made to define, whether is not present in a chain of breaks - whether well she carries out a current. For check the conductivity tester is used, the current in a chain is switched off. Attach connecting wires by both ends of a chain and if the test bulb is lit, means, the chain carries out a current well. If the bulb is not lit, somewhere in a chain there is a break. The same procedure is used for switch check, only the tester of conductivity is connected to switch plugs. At the switched-on switch the bulb should light up.

Disconnection search in a chain

At visual definition of a place of possible disconnection of a chain often there are difficulties since oxidation or shift of contacts is latent by sockets. Disconnection in a chain is often caused by oxidation or weakening of contacts. Having simply stirred socket contact on a perceiving element or in conducting, it is possible to restore the opened chain, at least temporarily. Disconnect the socket and spray it water from an aerosol ballonchik. On simple sockets sometimes it is possible to bend carefully socket contacts inside to improve contact - however be not fond of it not to damage the socket.

«on page back
16.1. General information
on page forward»
16.3. Removal and installation of the storage battery