How to check the mass on a car

What could happen to the car due to poor ground contact?

With the electrical equipment of any vehicle, malfunctions can occur that seem to people far from electricians to be the work of evil spirits.
And the culprit of mysterious malfunctions in the electrical equipment of a motorcycle or car, in most cases, is poor contact of the negative terminals - “ground”. But let's take things in order. Many drivers know that the method of connecting electricity consumers to a power source (generator or battery) on any vehicle is single-wire. The second (negative) wire is the body of a car or the frame of a motorcycle (trike, scooter, ATV, etc.). The very idea of ​​connecting the negative side of a power source (battery) to a steel frame or body is quite old and natural, as it can significantly simplify, lighten and reduce the cost of any vehicle.

A separate ground wire is used to connect the engine to the body or frame, since the engine hangs on rubber mounts that do not allow current to pass through, while both plus and minus are required by the starter, and, for example, by the carburetor solenoid valve. On foreign cars, especially injection ones, there may be even more consumers requiring electricity (and, accordingly, plus and minus). But the positive wires usually begin and end with quite reliable terminals, which are usually in completely sealed plastic blocks or rubber covers, but the negative wires are attached to the body or frame according to the principle “some water will find a hole.” And the body itself, in the place where the hole is drilled and the negative wire is secured, begins to rust very quickly, unless, of course, appropriate measures are taken immediately.

In addition, many do not take into account another important fact, which is known even to a novice electrician: aluminum and copper terminals cannot be connected to each other, since these metals, to put it mildly, are “not friendly” with each other, and begin to oxidize intensively. How can oxidized parts have normal contact? But I often see on the vehicles of inexperienced drivers, on the aluminum housing of the gearbox or engine head, a screwed-on copper terminal of the negative wire, which, in addition, is also washed by streams of water in bad weather.

A steel body or frame is also not friendly with copper, like aluminum, and forms an electrochemical couple. And the saddest thing about this is that the steel in such a connection will be blown away by two people and will corrode several times faster. As a result, the contact disappears (or there is a significant loss of current). Standard terminals installed at the factory are usually tinned. But under a thin layer of tin, which is easy to tear off when installing the terminal, there is still the same copper alloy.

Based on the above, it is obvious that the negative connections themselves to the body or frame are initially less reliable than the copper wires themselves and their copper terminals (tips). Now imagine, for example, in order for electricity to reach the carburetor solenoid valve, the electric current must go along a copper wire (copper bus) from the battery to the body, then along another wire to the engine, then along the intake manifold studs and their threads, often coated with sealant (or the studs are rusty), and finally go along the threads of the solenoid valve itself. Loss of contact in any of the listed places - and the circuit is open, and hence a whole bunch of malfunctions. As a result, the inexperienced driver is surprised - why did the carburetor suddenly begin to work poorly and gasoline consumption increase? You need to go to a carburetor specialist or buy another carburetor. But usually few people know that in such a situation the carburetor has nothing to do with it. And I gave one example of a sudden malfunction, but there can be many of them.

Therefore, in modern cars or motorcycles, full-fledged negative wires are increasingly used, because modern on-board electronics will not work without them, and most devices or programs will fail. On such equipment, reliable contact is especially important. Experienced electricians know, and I have already said this: in electrics there are only two faults - there is a contact where it is not needed, and there is no contact where it is needed.

Typical malfunctions on a car due to poor ground contact (but not all, we read about the rest below) .

These malfunctions, as I already said, seem like miracles to inexperienced drivers. It is not uncommon at a factory (especially a domestic one) to place the negative terminal of the headlight on a stud or bolt securing the headlight housing to the body, and then tighten it with a nut. At first glance, many will think that everything is correct, because the stud or fastening bolt is welded to the body. But the headlight housing is made of soft plastic, and the nut on the terminal cannot be tightened properly, otherwise the plastic will crack. In the end, it only takes a short drive on our roads to weaken such contact to the point of its complete absence. But in a standard headlight with a modest lamp of 55-60 watts, the current consumed even by such a lamp is quite large - up to 10 amperes (if both its threads are energized, both high and low beam).

In the end, a bad contact, if it does not disappear completely, will burn out, the resistance of such a connection will increase even more, and from a school physics course we know that the greater the resistance, the more heat is released when current passes in this place. This means that the burning of contacts will intensify even more (a vicious circle), and it’s not far from a fire (plastic burns well). And many young novice drivers, instead of a standard 50-60 watt lamp, install a hundred (100 watt), which consumes even more current. The consequences can be dire.

Weight - electric motor

The mass of electric motors is indicated without taking into account the mass of excitatory devices.  

In this case, the mass of the electric motor increases by 5 - 8 kg with a corresponding increase in its length.  

The weight of the electric motor was reduced by 18% and the dimensions were reduced. Reliability in operation has been increased due to the use of higher insulation classes of stator windings, better varnishes and enamels. The consumption of winding copper is reduced by 20 - 25%. The solid power scale has been expanded. The A series engines in the power range from 1 to 100 kW had 13 power levels, and the 4A series has 17 power levels, which allows you to more accurately select the engine power for the mechanism and avoid installing engines with excessive power. The starting torque of series 4A engines has been increased, for example, in the power range from 0-12 to 11 kW, the starting torque multiplicity is set at least two.  

Due to the use of high-quality steels, the weight of electric motors has been reduced by 18% and the dimensions of the motors have been reduced. Reliability in operation has been increased due to the use of higher insulation classes of stator windings, better varnishes and enamels. The consumption of winding copper is reduced by 20 - 25%.  

The masses of the pumps are indicated without taking into account the masses of the electric motors and the common foundation plate.  

Part of this heat dql is absorbed by the mass of the electric motor, as a result of which the temperature t and overheating of the motor increase.  

Frequency converters make it possible, with the same power, to reduce the size and weight of electric motors powered by high-frequency currents of 200, 400 Hz and more. Reducing the weight of hand-held power tools improves working conditions, as it reduces the physical load of the worker. In this case, increased electrical safety is achieved only due to low voltage, since current with a frequency of 200, 400 and even 500 Hz is just as dangerous as 50 Hz. In branched networks at higher frequencies, the danger increases due to an increase in the capacitive conductivity of the phases relative to the ground.  

Frequency converters make it possible, with the same power, to reduce the size and weight of electric motors powered by high-frequency current - 200, 400 Hz and more. By reducing the weight of hand-held power tools, working conditions improve, as the physical load of the worker is reduced. In this case, increased electrical safety is achieved only due to low voltage, since a tone with a frequency of 200, 400 and even 600 Hz is just as dangerous as a current with a frequency of 50 Hz. In branched networks, the danger increases even due to an increase in the capacitive conductivity of the phases relative to the ground.  

Frequency converters make it possible, with the same power, to reduce the size and weight of electric motors powered by high-frequency current - 200, 400 Hz and more. Reducing the weight of hand-held power tools improves working conditions, as it reduces the physical load of the worker. In this case, increased electrical safety is achieved only due to low voltage, since current with a frequency of 200, 400 and even 500 Hz is just as dangerous as 50 Hz. In branched networks, the danger even increases due to an increase in the capacitive conductivity of the phases relative to the ground.  

Improved design and the use of new advanced materials have made it possible to significantly reduce the overall dimensions and weight of electric motors (by 20%) and improve their electrical characteristics. For all products or groups of products certified by the State Quality Mark, special state standards are developed, which establish the highest technical level of quality achieved in the production of certified products. These standards indicate the achieved indicators, such as reliability, durability, testing and control methods and other data. Standards for certified products are put into effect immediately after approval and are binding only for enterprises producing products marked with the state Quality Mark.  

.3.3. Poor Ground Detection

The negative terminal of the battery is connected to “ground” - the metal of the body, engine or gearbox; Moreover, many elements of electrical equipment are connected in such a way that only the positive wire is suitable for them, while the current returns to the battery through the metal of the body. This means that the electrical component mount and the body are part of the electrical circuit. As a result, poor or corroded fasteners can cause the element to fail or cause it to perform erratically or poorly. In particular, light bulbs may glow dimly (especially if the light bulb's ground point is connected to another electrical component that is still on), electric motors may run slowly, and the operation of one circuit may have a seemingly unnoticeable effect on the operation of another circuit.

Don't forget that many vehicles use ground wires between certain components such as the engine/transmission and the body, that is, in areas where there is no direct metal-to-metal contact due to soft rubber mounts or a layer of paint.

To check the reliability of the element's grounding, it is necessary to disconnect the battery and connect one of the ohmmeter probes to a reliably grounded element. Connect another probe to the wire or connection to the body that needs to be checked. The resistance shown by the ohmmeter should be zero; if not, check the connection as follows.

If you suspect there is no ground, disassemble the connection and clean the body area and wire terminal (or the grounding surface of the element) to bare metal. Carefully remove all traces of dirt, then use a knife to remove all paint so that there is reliable contact between the two metal surfaces.

Also interesting: What is the difference between the Niva Urban and the regular Niva?

When assembling, tighten the connector securely; When connecting a wire terminal, install a serrated washer between the terminal and the body surface to ensure a secure connection. When connecting, prevent future corrosion by applying a layer of Vaseline or silicone grease.

How to check mass with a multimeter

Disconnect the negative terminal of the battery

We take a multimeter and switch it to resistance measurement mode up to 200 Ohms. We check the resistance of the probes themselves by connecting them together

The resistance of the probes themselves is 2.1 Ohms.

Now we connect one probe to the engine. At least here

And the second probe is to the engine control unit, which, in turn, is screwed to the body

What happens - the mass resistance of the engine - the body has practically no resistance? Is everything perfect? Is the engine and body weight OK? What is the problem then? Is the starter defective or are otherworldly forces overcoming you?

Where is the mass of the Chevrolet Niva engine?

But if everything is in order with the relay, and the devices do not work, then there may be a problem elsewhere - the mass attachment point. The negative wire coming out of the battery is connected to the car body and goes to some of the main energy consumers in the form of wires. This is sometimes the difficulty when calling an electrician.

The architecture of the circuit can be described as follows: a wiring harness comes out of the negative terminal, connecting devices operating from one ground point, then wires connecting other ground points are connected to them using a crimp sleeve. As a result, finding a specific mass attachment point is quite difficult.

For example, the mass of the mirror control unit is located behind the trunk trim. But with the engine everything is a little simpler. Since it is connected to the frame and body through pads, which are essentially a dielectric, it has its own wiring harness. The terminals are located on the left side of the engine, below the ignition module. They are responsible for the operation of the ECU and ECM sensors.

ECM weight

For SAMAR with a 1.5 liter engine, the mass for the ECM is taken from the engine housing, from the fastening of the plugs . The plugs are located on the right side of the block head.

For SAMAR with a 1.6 liter engine, but also 1.5 liter engines, which have a new generation ECM (Bosch 7.9.7, January 7.2), the weight of the ECM is taken from a welded stud. The pin is attached to the metal frame of the instrument panel to the floor tunnel (under the ashtray). In practice, it happens that this pin is painted at the factory and is loosely tightened. Therefore, over time it may become loose and at the moment the fan is turned on, there will be a drop in the voltage of the following sensors (which will lead to jumps in speed): DTOZH, TPS, MAF.

Solutions to the problem

If power outages occur frequently or current leakage occurs during long periods of parking, you can improve the system to solve the problem. It’s not difficult to get the job done; the minimum set of tools that every motorist should have is enough. The procedure depends on the nature of the malfunction.

How to make mass better

If removing and cleaning the contacts does not produce any effect, you will have to use more radical repair methods. In some models, the problem with a minus on the body is a real “disease”, so it is necessary to improve the design in order to eliminate the manufacturer’s shortcomings:

It is necessary to monitor the condition of the wires and replace them if there is even the slightest doubt about reliability. It is best to use the same elements as those installed, plus high-quality fasteners.

Installing the mains switch

The switch will protect the car from current leakage, short circuit, and can also serve as an additional anti-theft system. It’s easy to install it yourself; most often, one of two options is used:

The switch is not suitable for cars with an alarm and central locking, since if there is no ground, the system will not work. It is also undesirable to install it on models with a lot of electronics.

It is not difficult to locate the ground wires; they should be periodically removed and processed to ensure good contact. When checking, it is better to use a multimeter, this is the easiest way to detect damage if it is present. It is recommended to replace worn wires in a timely manner, and to prevent leaks, you can install a power switch button.

Where is the ignition relay located on a Niva Chevrolet?

The ignition relay is located in the passenger compartment fuse box; it can be found on the driver's side of the instrument panel, opposite the seat. On the diagram it is usually designated K6 and in the technical description it is sometimes called an addition relay.

Also interesting: Niva-Chevrolet with an Opel engine: brief description, technical characteristics, owner reviews

It is responsible for turning on the fuel pump and supplying voltage to other elements. Triggered when the ignition key is turned. At this moment, you can hear a click behind the instrument panel. This electric coil built into the relay receives voltage and closes the contacts of a certain circuit. If there is no characteristic sound when turning the key, this may indicate its failure.

ADDITIONAL MASS WIRES

If the weight of the engine with the body is bad, then problems arise:

When symptoms of poor engine weight appear, there is a way out of the unpleasant situation - in this case, additional weight on the engine will help. You can install an additional wire in different ways, the most important thing is that it reliably connects the car body with the power unit. For example, one end of the wire can be attached to the stud of the upper shock absorber support, and the other to the stud of the intake manifold of the internal combustion engine. It is important that the wire has a large cross-section, preferably no less than that of the bulk itself.

On new machines, problems with mass wires rarely occur. But on older models, the body studs rust. Finding a lack of ground is not so easy, so car owners use the installation of additional wires. So the additional mass on the generator helps eliminate battery charging leakage.