Meanwhile, the reason is often on the conscience of the car owner himself or the unfortunate repairman who helped him, forgetting that any button, switch, switch is designed for a specific operating current. Exceed - it starts to heat up, the contacts burn, the plastic melts … and the end.
In fig. 1 - the simplest switching scheme: current source - switch - consumer. This attracts. But here is its minus. If the consumer is powerful, a large current must pass through the switch - not every “button” can withstand at least several switches without consequences.
In photo 1 there are several well-known switches that are usually located in the cabin and most often operate according to scheme 1. The first is the ignition switch 1 with a lock. Its contacts, supplying power to the ignition system and a number of other consumers, are designed for a current of about 20 A. The starter pull relay is activated by an independent pair of contacts.
The switch of 2 marker lights and headlights "Volga" is capable of holding sufficiently large currents of headlights. The getinax base and sliding self-cleaning contacts inside provided sufficient reliability of the device at low current losses. And by switching the light (“near - far”), a traditional device 3 with a lever on which there are necessary symbols is in charge. This switch is also designed for currents consumed by headlights.
Automatic fuse 4, which makes disposable fuses unnecessary, is very convenient in operation: at a current of more than 10 A, the bimetallic plate, bending, opens the contacts. After removing the cause of the circuit, it remains only to press the fuse button to connect the circuit. Of course, the design is more complicated, and the dimensions are too big - for example, it is not easy to integrate into the mounting block.
Two more “high-current” (designed for high currents) switches are the cigarette lighter 5 and the “mass” switch 6. The cigarette lighter is about the same machine as the fuse already mentioned: it switches itself off after heating the coil. As for the “mass” switch, whether or not to set it is up to the owner. Here are their pros and cons. For example, not all modern electronic systems "love" to be often turned off.
In fig. 2 we show another, now most often used, consumer power circuit - through a relay. In this case, a significant part of the circuit - from the battery to the switch and then - to the relay is laid with thin wires, and the switch turns out to be "low-current". But the power contacts of the relay and power wires are still designed for the current required by the consumer. Inexperienced people sometimes connect powerful additional consumers, as shown, to the relay. This is impossible: both thin wires and the circuit breaker may be overloaded.
In general, on the car you can find both of the considered connection schemes for consumers. For example, photo 2 shows the steering column switch 1, which according to the scheme in Fig. 1 works in VAZ 2101, 2102, 21011, 21013 and ZAZ 968 M. The fact is that the headlights of these cars were equipped with ordinary lamps. And the installation of more powerful halogen ones here without the necessary modifications to the circuit led to an overload of the switch, heating of the contacts, their burning. And the case ended in failure. On later models VAZ 2104, 2105, 2106, 2107, this switch has already been turned on according to Scheme 2. By the way, the refinement of the previous “penny” according to Scheme 2 with the same lamps improves headlight, as many were convinced.
Switches 2 and 3 operate only in the second circuit. One knows the light of the dimensions and headlights of VAZ 2113, 2114, 2115 cars. The other has long been familiar with everything - it commands light and direction indicators or wipers.
Most often, according to the first scheme, the 4 power window switch also works - oh and the poor fellow gets it! Some do not accidentally carry a spare. It would seem that this is complicated: let's turn on according to the second scheme! But imagine that you do not have two windows, but all four, and in addition a window closing module … It will be difficult to post. Cheaper to change switches.
But the brake light switch 5 (“frog”) is a special song. It is everywhere included according to the scheme in Fig. 1 - cheap, but … is it angry? There are many cases where, even with standard lamps, not to mention more powerful ones, the contacts heated up, the plastic melted. Additional “stoppers” only aggravate the problem: once the owner of VAZ 2110 turned to us, “tired”, as he said, “frog” to change. We redid everything according to scheme 2 - there is no problem.
On a photo 3 - salon lamps, here also trailer light switches. The latter work according to the simplest scheme. The trouble for all is one - moisture, dirt, corrosion. Experience has shown that cleaning does not help for long. Inexpensive limit switches it makes sense to replace on time.
On a photo 4 - examples of special, electronic switches. These circuits do not commute mechanically - there are no cams or contacts. The crankshaft position sensor 1 opens the magnetic flux and generates an electrical impulse to the injection engine controller. But switch 2 of the contactless ignition system - it turns the ignition coil on and off at the right time. The latter on VAZ 2108 is ten times more powerful than on the "classic" - it is not possible to commute with ordinary contacts for long.