17.3. Search of malfunctions - the general of data
The consumer, the switches, the relay and wires connected according to the enclosed scheme (see below) are a part of electric chains of the car. Before starting troubleshooting it is necessary to study the scheme and to define a possible source of malfunction. For example, the problem of troubleshooting is considerably facilitated if it is possible to check serviceability of other consumers directly or indirectly connected to the suspected chain.
If the refusal of several consumers is observed, then the break of connection with weight or burn-out of a safety lock is the most probable cause. As a rule failures of electric equipment are caused by weakening of contacts or their corrosion, burn-out of a safety lock or an oplavleniye of a crossing point. Search of malfunctions as a rule is carried out by means of a tester (voltmeter) or a control lamp which are connected between the site of a faulty chain and well smoothed out weight.
Connecting a tester or a lamp consistently on a contour of a chain it is possible to reveal the faulty site which is found on loss of tension or blackout of a lamp.
For search of short circuit in wires it is necessary to get a safety lock of the checked chain and in a gap to connect a lamp or the voltmeter. With a weight points fire of a lamp when rocking wires to short circuit here and there (the tester has to show tension). When checking it must be kept in mind that some consumers receive food at position of the ASS or Run ignition key.
For check of reliability of connection with weight connect through an ohmmeter (or through a control lamp to the battery) the checked connection of a wire with weight and well smoothed out site of weight. If the ohmmeter shows a chain (or the lamp will light up), then connection with weight reliable. Otherwise the contact with weight is broken. Keep in mind that in most cases weight serves as the return current distributor connecting a chain to a negative pole of the battery. Therefore violation of connection with weight, or a gap in a chain of the return current on the battery, can be the main reason for refusal.