Rear window defogger does not work. What to do? Step-by-step instruction. What to do if the rear window defroster does not work? How to make a break in the heated rear window

The rear window heating system of the vehicle is a common equipment for almost every modern car. The purpose of this functional addition is to remove ice crust or perspiration from glass in winter. If the heated rear window does not work, visibility deteriorates, and the driver loses the ability to rationally assess the circumstances on the roadway behind his own car. Safe driving can be restored as soon as possible.

Heating system device

To understand how to restore the heated rear window, it is worthwhile to first study the principle of operation of this system. Its purpose is to eliminate fogging and prevent dry air in the passenger compartment. In winter, this function is indispensable, since the icing evenly leaves the glass and at the moment when you already need to go, the view is 100% free.

The principle of operation of such a system in the case of a windshield is the effectiveness of directed air heat flows.

When it comes to the rear window, compact heating elements come into operation, the source of which is the electrical network. Metal tracks are fixed to the glass surface from the side of the passenger compartment. These are numerous thinnest ribbons through which electricity passes, activating the process of heat release. As a result, due to the heating of the glass, water evaporates and the surface becomes transparent in a couple of minutes.

Scheme of work

To know how to restore the heated rear window of a car and to approach the repair with a high level of professionalism, study the principle of operation and the electrical wiring diagram. From the + terminal of the battery, power is directed to the ignition switch, then to the fuses and last of all to the controller. After such a path, it follows to the power contact of the relay. The vehicle body is connected to the negative terminal of the battery. Activation of the heater supplies voltage to the relay winding, then the power contacts are closed, and the relay outputs are also connected. The current flows through parallel-connected heater strips, then enters the negative terminal through the machine body.

Remember, activation of the heater is only possible when the ignition key is activated.

In some cases, a running motor acts as a factor conducive to activation. This feature is due to the fact that the battery should not be discharged prematurely, and given the characteristics of each car brand, the consumption of this system can be 10-25 A.

Sources of the problem

Since many drivers prefer to restore the rear window heating with their own hands, you need to know about the repair options, taking into account the source of the problem. There will be no obstacles in self-checking the functional units of the car if you have minimal skills in repairing automotive equipment.

The safety element is the first thing that should get your attention when a breakdown is detected, since the system will not work if it is burned out. The localization of this element varies depending on the model of the car, so at this stage you will have to turn to the vehicle service book for help. Next, remove the fuse and make sure it works. The repair of the heated rear window will be limited to replacing the burnt-out element.

A breakdown of the system relay can also lead to a stoppage of heating. In such a situation, installing a fresh element will also be sufficient.

Wiring

If replacing the fuse does not correct the situation, go to the power supply wiring diagnostics. A burnout, breakage of an attachment or a fracture helps to stop the flow of current to the heating poles. To detect this circumstance, turn on the heating button and measure the voltage of the terminals with a tester. The terminals can be found at the bottom of the glass or on its sides. The lack of voltage on the wires should alert you.

Examine the entire path of the wiring for integrity, strip the contacts of the terminals and connections. Oxidation in these areas often leads to a blockage of the voltage supply. If you could not cope with this task on your own, an auto electrician will help you.

If the heating tapes are damaged, it may also be necessary to restore the heated rear window. To know how to do this, you must first study the specifics of the workflow in this zone. The heating element receives voltage and then the energy follows the threads. In relation to the base, they are connected in parallel and act as conductors of currents. Their heating is due to a certain amount of resistance, despite the insignificant heating temperature, this is sufficient for its purpose. If one or several threads are damaged, the current does not flow through them, therefore, these areas do not warm up. The features of repair work in such a situation are described a little below.

Governing bodies

If all the elements that you checked earlier are working properly, you should pay attention to the power button. You can determine the operation of the system by the illuminated indicator light, which makes itself felt after pressing the button. If everything is activated and the corresponding indicators have made themselves felt, but the glass is not heated, wear or burning of the working contacts of the toggle switch is likely, so the energy is not supplied. Repairing a heated rear window of a car requires only replacing a button.

Imported cars

In the case of imported cars, repairing the rear window heating with your own hands will not be limited to diagnosing the standard heating system, since the rear-view mirrors are also equipped with heating. Activation of the heating of the stern glass leads to a parallel activation of the heating of the mirrors. If the system does not work on both zones, it is most likely that you are dealing with the reason discussed in the first paragraph - a fuse or relay.

It is important to determine which fuses are associated with the glass, because there are several of them. It will not be superfluous to diagnose the electronic board, which often wears out due to unsoldering contacts and breaking tracks.

Phased repair

It is of paramount importance to carry out diagnostics and purchase a repair kit. There can be several options for a repair kit, and the repair technology in each of the cases is considered below.

In addition to visual diagnostics of the condition of the threads, there are several more reliable and effective methods:

1. Visual diagnostics requires activating the heater when the rear window is fogged up. Where the threads are broken, the surface will warm up almost instantly, while in other areas visibility will be problematic.
2. Using a voltmeter requires activating the ignition and then turning on the heating system. One probe should lie on the vehicle ground, and the other near the center of the heating tape. First, wrap the second probe with foil. The break will be localized in the zone where the voltage rises to 12 V or drops to zero. Ideally, this parameter should not exceed 5 V.
3. The second method of using a voltmeter involves fixing one probe to the positive terminal of the heater, and the second must be moved along the negative terminal strip. The problem area will be where the voltage will be zero.
4. Using an ohmmeter requires activating the kilo mode. The device must be analog, with an arrow. The probes should be located near the system leads, which are on opposite sides of each other. Use distilled water to wet the cotton wool, which must be smoothly passed along the tape. As soon as the arrow of the device twitches, you will be able to detect the cliff zone.

Repair with conductive adhesive

The rear window heating filaments can be repaired with conductive adhesive. It is designed for temperatures ranging from -60 to +100 degrees. You should not choose kits with glue, the cost of which is 150-200 rubles. Often they do not last long or they may not be effective at all. A cost of 300-400 rubles will be optimal for such a set.

Work order:

1. Study the instructions supplied with the kit. You should have a clear idea of ​​the options for applying the composition and the speed of its full drying.
2. Prepare the problem surface. Dampen a cloth with alcohol and wipe the area.
3. Lightly sand the edges in the break area with zero emery paper. It is enough to simply remove plaque and carbon deposits in two strokes.
4. Use scotch tape to glue the strips along the thickness of the sides. It should not overlap the thread, but also avoid leaving a long distance from the tape. Focus specifically on the width of the thread.
5. Proceed with applying conductive adhesive to the prepared area using a brush or syringe. The instructions will tell you how many layers you need to apply. The overlap on the working areas of the belt should be 1 cm to the left and right.
6. Dispose of the tape and wait until the composition is completely dry. This will not happen before a day.
7. Check the functionality of the system after drying.

Among the popular and reliable manufacturers of a repair kit, which includes threads, it is worth highlighting Quick and Permatex. Such options are suitable for repairing even large areas, even if we are talking about 10 cm. The complete set assumes the presence of heating tapes, polymer resin in the form of a spray can and stencils.

Heater repair is reduced to the following steps:

• determine the break zone and prepare a thread of the appropriate size;
• remove the protective film and use resin to fix the thread in the desired area;
• after complete drying, repeat the manipulations and check the result after 2 days.

Alternative method

Alternative methods are also suitable for restoring threads. The difference between them lies only in the material used:

1. Shavings combined with paint. The first material can be obtained from a bar of copper and brass, which must be filed. Choose a paint that matches the shade of the heating tapes. Mix the ingredients in equal proportions until you achieve a soft dough consistency. Use tape or tape to create a stencil. Stick on the stencil and activate the heating. Contact can be determined by the characteristic hiss. Stencil the mixture. This method eliminates the need to wait a day. You can operate a car immediately after the performed manipulations.
2. Soldering of the break point is carried out using zinc chloride. Give preference to solder with a minimum tin content - POSS-4-6 or POS-18. A copper or silver core is suitable for repairing a large section of tape.

There are such malfunctions in the car in which you can drive as before, but they constantly bother you, cause unpleasant feelings. Such malfunctions include the failure of the glass heating circuit at the rear of the car.

Usually, this electrical circuit is always amenable to repair. And there are troubles with these threads for the following reasons:

• crack in the window;
• failure of contacts;
• open circuit;
• natural wear and tear of a part of the track on the window;
• mechanical scratching of the track.

The most common thread break occurs on the window. Sometimes it can be determined visually, but more often with the help of an instrument. Next, we will figure out how to diagnose, and how to repair the heated rear window.

How to restore heat with glue

Let us analyze the step-by-step process of repairing the heated rear window when the thread breaks with our own hands. Useful for us:

• electrical tester;
• conductive adhesive used for glass repair;
• tin foil;
• Scotch;
• solvent, clean cloth.

Read also about and.

You can buy special glue for repairing the heated rear window at a regular auto shop. We start repairing damaged heating threads by turning on this system with a button in the cabin.

1. First of all, we determine the place of the gap. To do this, turn on the tester in the voltmeter mode and, applying the foil to the thread on the window, check the thread through the foil with a probe, moving from the positive contact. In this case, we apply another probe to the negative contact of the heater.
2. At the break point, the voltage will jump from zero to several volts.
3. Next, we wipe the gap with a solvent.
4. We glue the tape on the top and bottom of the thread, leaving a distance for the thickness of the thread.
5. We apply conductive glue for repairing heating threads with a syringe or brush. It all depends on what is offered in the set with glue. In addition to the empty space in the gap, we coat another centimeter of each end of the whole thread.
6. We remove the scotch tape. We wait about 24 hours until the glue is completely dry.
7. We remove the excess, wipe the place of repair.

This is how the damaged threads of heating the rear window are repaired with their own hands. It is clear that you will have to buy a set with glue beforehand.

What to do with contacts and other methods

Now let's talk about how to repair broken rear window heating contacts. To do this, you must first understand the principle of building this electrical circuit.

It turns on only when the ignition is on, an additional relay is responsible for this. It supplies power to the system button. When the button is on, the lamp lights up in parallel and the switching relay, powered by the fuse, is activated. Further, the voltage is supplied to the heating threads.

Repair of glass heating contacts consists in restoring their performance. To repair any faulty rear window heating terminal, we need:

• multimeter;
• screwdriver;
• soldering iron, solder, rosin.

All the manipulations described below are available on the Internet as a video with the title: "DIY glass heating repair." We will write further in words. So the actions are like this.

1. We check all the elements of the circuit to find the location of the malfunction. First, we look at the fuse.
2. Next, we check the serviceability of the button by measuring the contacts with a multimeter when it is turned on.
3. We check the relay, when it is triggered, the corresponding contacts should give out a voltage of 12 V.
4. We measure the voltage of the connector at the rear window.
5. We check all the wires going from the button and relay to the heating track system, see what the state of the insulation is, if there is a short circuit to the car body.
6. We restore the faulty place by replacing the terminal, additional insulation or soldering the contact.

This is how the contacts for heating the rear window of the car are repaired. If the chain break is on the threads, then we find a specific place according to the algorithm already described above with the help of a tester. Further, in the absence of purchased glue, you can fix the thread break like this.

Let's prepare:

• brass or copper bar;
• file;
• red paint;
• Scotch.

1. Use a file to prepare brass or copper shavings.
2. Mix the paint with shavings in a 1/1 ratio.
3. We turn on the heating.
4. We glue the adhesive tape on top and bottom of the faulty area, leaving a distance commensurate with the thickness of the thread. We clean this area.
5. We apply a composition of paint and shavings.
6. We wait for drying for a few minutes. We remove the scotch tape.

This is such an interesting technology. There is another option for restoring the lost section of the heating track in the absence of special glue. Let's consider it on the example of a specific car.

To repair the heated glass at the rear of Renault Logan, we need to use the following accessories:

• copper sulfate (purchased at a fertilizer store);
• battery electrolyte (sold in any auto shop);
• a piece of copper bar with a diameter of about 6 mm;
• a piece of regular cloth.

This method is called electrolytic. You need to make the following manipulations.

1. Wrap the end of the bar with a piece of fabric so that the tip hangs down slightly, and, moreover, fix it so that it does not fall off.
2. You can prepare a solution for work in the following proportion: half a glass of water plus two teaspoons of copper sulfate, literally a hundredth of the electrolyte. Stir everything.
3. We connect a bar with a rag as an electrode to the positive terminal of the car battery. In this case, the contact of the thread on the glass with a minus of the chain must be serviceable.
4. We dip the resulting positive electrode into the solution and drive it along the lost area of ​​the heating track. The copper from the solution should cover the entire area.

This method works well for all small scratches. In addition, it is not as difficult to perform as it might seem at first glance.

Heat recovery price

However, if you still do not want to do anything yourself, it is enough to contact a car service, where the entire electrical circuit will “ring” completely, quickly find the place of the defect and professionally repair it.

And what is the price for glass heating repair is spelled out in the following table. Here it is - with average data for large Russian cities.

Town	Price
Moscow	RUB 1100
St. Petersburg	1050 RUB
Ekaterinburg	RUB 1000
Samara	RUB 900

Here are the values ​​obtained during work of average complexity on a popular budget foreign car. For VAZ it will turn out a little cheaper - twenty percent. It's just that car services always charge a little less for domestic cars, it so happened, although somewhere the mechanisms are simpler on foreign cars.

It began to get colder outside and in the morning more and more often the first thing to do is to press the rear window heating button. But the HORROR, you turn on the heating and find that not all the threads are heating. What to do? Replacing glass is not a cheap pleasure, it remains to repair on your own. Generally Recommended Repair Methods

the heating threads of the rear window, according to those who have tried it, leave much to be desired - the ineffectiveness of inexpensive conductive adhesives, and the high price of proprietary mixtures.

And in the vastness of the network I met an interesting repair technology, the reviews of those who tried it were more than enthusiastic:

Description of the technology.

Of the reagents, copper sulfate is needed - better known as copper sulfate (used in plant growing and construction), and sulfuric acid - an electrolyte from a battery is quite suitable. From the tool - a piece of copper (preferably copper - not brass.

Several pieces of copper wire folded into a bunch are quite suitable) of a tube or rod with a diameter of 6-10 mm and a strip of fabric 20-30 mm wide and about half a meter long. At the end of the bar, wind a strip of fabric halfway up its width - you should get something like a brush. Above, you need to put a bandage of thread so that the fabric does not unwind.

Electrolyte preparation - not to be confused with akka electrolyte - it is also not difficult. A couple of teaspoons of copper sulfate are poured into half a glass of water, and stirred until dissolved. Not completely dissolved - not scary, do not pay attention. In the resulting solution, add 0.2-0.3% percent of concentrated sulfuric acid or 0.5-1% electrolyte for the battery - this is about half a teaspoon of electrolyte for these half a glass.

Well, the process itself. Both terminals of the glass are connected to “ground” (if the glass is installed in the car and at least one heating thread is intact on it, nothing needs to be done), and the “plus” of the battery is connected to the tube with a rag.

We moisten the positive electrode in the solution and start actively and continuously rubbing the thread break for 3-5 minutes. A current passes through the solution, which transfers copper ions from the electrode to the heating filament. With a slight damage to the thread, the gap is completely tightened with copper, with large gaps, the copper-plated areas should be irradiated with an unheated soldering iron and a jumper from a thin wire should be soldered.

There is no need to limit the current as after a few seconds, the anode is passivated and limits the flow
current. It should not be forgotten that the solution contains sulfuric acid - this concentration is not dangerous for the skin, but
on clothes in a week - two holes appear (Therefore, I do not advise carrying out the process without removing the glass, although this is quite possible.

• A couple more ways ... ...

1st way:

- turn on the heating on the fogged glass and in the place of the break the glass quickly sweats with a stain, while the whole thread with the break does not sweat.

2nd way:

- to detect a break in the rear window defroster wire, turn on the ignition and turn on the rear window defroster.
- connect one probe of the voltmeter to the mass of the car, and wrap the second probe with foil and move the foil along the heater conductor.
- Connect the voltmeter probe in the center of each wire of the rear window defogger. If the voltmeter shows a voltage of about 5 V, then the heater conductor is working. If the voltmeter shows a voltage of 0 V or 12 V, then there is a break in the heater conductor.

- to locate the break in the heater conductor, connect one probe of the voltmeter to the positive terminal of the heater, and move the second probe along the conductor of the heater from the side of the negative terminal of the heater. The point at which the voltage indicated by the voltmeter will drop from a few volts to zero is where the heater conductor breaks.

3rd way:

- ohmmeter, in kilo mode, or better mego. One probe clings to one terminal of the heater, the second probe to the other terminal of the heater. Take a piece of cotton wool soaked in distilled water and lead it along the strings of the heater, follow the kilo readings, the megohmmeter at the break point, the arrow jerks.
- it is better to use an analog ohmmeter (with an arrow).
- works if there is a break in one place ...

Directly repair threads:

In all the methods listed below, you must first clean the conductive strip from varnish (better - with a bent steel wire, a paper clip) until a metallic sheen appears and degrease.
1st method (conductive paste):

- the broken conductor of the rear window defroster can be restored using conductive paste.
- before starting the repair, turn off the heated rear window and allow time for the glass to cool.
- being careful, clean the heater conductor and rinse it with alcohol.
- use adhesive tape to mark the area to be repaired.
- Apply electrically conductive paste approximately 20 mm from each end of the damaged conductor.
- After drying the electrically conductive paste, the rear window defroster can be used for 24 hours.

It can be dried at a high temperature, then the heating can be used earlier.
2nd method (electrolytic coating):

- from the reagents, copper sulfate is needed - better known as copper sulfate (used in plant growing and
construction), and sulfuric acid - the electrolyte from the battery is quite suitable.

- from the tool - a piece of copper (preferably copper - not brass. Several pieces of copper wire folded into a bunch are quite suitable) of a tube or wire with a diameter of 6-10 mm and a strip of fabric 20-30 mm wide and about half a meter long.

- at the end of the thread, wind a strip of fabric on half of its width - you should get something like a brush.

Above need to put a bandage of thread so that the fabric does not unwind.

- preparation of the electrolyte - not to be confused with the electrolyte of the accumulator - is also not difficult. A couple of teaspoons of copper sulphate is poured into half a glass of water, and mixed until dissolved, not completely dissolved - not scary, do not pay attention.

In the obtained p-p it is necessary to add 0.2-0.3% of the percentage of concentrated sulfuric acid or 0.5-1% of the electrolyte for the battery - this is about half a teaspoon of electrolyte for these half a glass.
- the actual process.

Both terminals of the glass are connected to the "mass" (if the glass is installed in the car and at least one heating thread is intact on it - nothing needs to be done), and the "plus" of the battery is connected to the tube with a rag. We moisten the positive electrode in solution and start actively and continuously rubbing the thread break for 3-5 minutes.

A current passes through the solution, which transfers copper ions from the electrode to the heating filament. With a slight damage to the thread, the gap is completely tightened with copper, for large gaps, the copper-plated areas should be irradiated with an undamaged soldering iron and soldered a bridge from a thin wire.

There is no need to limit the current, because after a few seconds the anode is passivated and limits the flowing current. Do not forget that the solution contains sulfuric acid!

3rd method (paint with shavings):
- take a copper-brass bead (graphite is also suitable) and began to make a line with a small file.
- paint (you can red, to match the color of the threads) is mixed with the stitch, the proportion is about 50/50. You should get a dough mixture.
- heating is turned on and paint is applied to the thread, first making a clip from electrical tape or scotch tape. V
During the process of applying paint, a hiss appeared from the place of contact, then it disappeared, but the thread was hot.
- done. Literally in a minute, the composition freezes.

4th method (magnet and glue):
- prepare very small iron filings, a small magnet (from the speaker) and transparent glue (such as BF-2) or nitrolac.
- attach a magnet from the outside above the break, then sprinkle sawdust on the side of the conductor, gently moving the magnet to achieve electrical contact at the break (this will be noticeable by the heating of the strip - unless, of course, the break is in one place, otherwise a larger number of magnets will be needed).
- Apply a drop of glue to the sawdust with a small white brush and let the glue (varnish) dry.
- then remove the magnet and use a blade to remove excess sawdust. You can reapply one more layer of glue (varnish).
- enough for several years.

5th method (special adhesives):
- special adhesives for the restoration of heating threads, there are also Russian-made
- the reviews are contradictory, some like it, some don't
- instructions for use are attached to the glue
- it is recommended to add a little iodine to the glue. In this case, the glue turns out to be red and matches the color of the rest of the threads.

6th method (soldering):
- Damage sites can be soldered with a soft low-tin solder POS-18 or POSS-4-6, using zinc chloride as a flux. If a long section is damaged, it is better to solder a thin copper or silver vein from the wire.

7th method (sawdust and glue):
- silver sawdust (for example, an alloy cut off with a file from the contact of an unusable power relay) must be poured into the fold of a sheet of paper, and a drop of nitro glue must be added there. Quickly roll up a cylinder 2 ... 3 long and 1 mm in diameter with the tip of a knife and place it on the damaged site. Then - crush to squeeze the sawdust tightly, and remove excess.

To implement this idea, I used the second method - electrolytic coating.
Here was the gap:

it was visible to the naked eye, but just in case, I called this place with a tester ... Then I made a device with which copper ions will be applied:

it is done very simply ... he took 3 copper conductors from a copper wire of 2.5 mm cross-section, soldered them together, put a heat-shrink tube on them, cleaned the copper, wound a rag about 3 cm wide, fastened it all with ties ....

on the other hand, I soldered a plug-in contact so that you can connect this device instead of heating. Then copper sulphate began to play, fortunately, there were old stocks and took a little acid from the battery with a syringe .... (Copper sulphate can be bought at a store where fertilizers are sold).

Then everything was according to the instructions .... Put the electrode into the glass, disconnected the positive wire from heating the glass, connected a homemade electrode to it, turned on the ignition and the heating button - thus "+" appeared on the electrode ...

There is a "-" sign on the heating strips. I just walked around the place where there was a gap and saw how a coating of copper was formed ... I note that this method is most effective for small scratches ... For reliability, I also soldered this place, since after such a copper plating procedure everything is soldered with a bang!
In the end, everything worked out and everything works!

Freezing and fogging of the rear window leads to a decrease in visibility, which limits control over the traffic situation. In the article, we will consider all the heating components, as well as their possible malfunctions. We will show you how the rear window heating is repaired.

How the system works

To easily find a malfunction of the rear window heater, consider the system design. All elements are shown in the schematic diagram.

1. Mounting block.
2. Heating switch relay.
3. Egnition lock.
4. Dashboard button. A light is installed inside the button, which lights up when the heating and ignition are on.
5. The corresponding icon on the dashboard, duplicating information about the included heating.
6. Conductive threads located on the rear window.

The principle of operation of the entire system lies in the heating effect, which manifests itself when current passes through the heating element. Such in the rear window heating system is a network of conductive threads. When the ignition is turned on in the 3rd position (On) through the fuse (in our case, F7), power is supplied to the system power button. After pressing the button, the current, lighting the control lamp, goes to the corresponding icon on the dashboard and back to the mounting block to the switching relay. After the corresponding contacts of the relay are closed, power is supplied (+) to one of the terminals of the system of conductive threads. The second terminal is connected to the car body corresponding to the negative terminal of the battery. Thus, a current begins to flow through the threads.

Now it is easier for us to understand how to repair the heated rear window. For a successful repair of a heated rear window of a car, it is advisable to be able to read electrical diagrams, since not for all cars you will find such clearly depicted elements as in the diagram provided by us.

Malfunctions

How to find the reason

All manipulations to find the cause of the breakdown should be done after checking the fuse. Also, the very nature of the breakdown can often suggest a way to troubleshoot.

For example, together with the heated rear window, the light in the button stopped working. It is likely that this is just a coincidence, as the light bulb may have simply burned out. But the contiguity speaks of the likelihood of a lack of power going to the button. In this case, according to the above diagram, you need to check the circuit from the ignition switch, terminals 1 and 9, 2 and 4 on the mounting block, 85 and 86 relay contacts, as well as the button itself.

There is no heating of the filaments, but the light in the button works after switching on. In this case, the power to the button is exactly coming, therefore there is a breakdown in the circuit after the switch. It is necessary to check fuse F4, the heating relay and the corresponding terminals in the mounting block, as well as the contacts of the heating threads.

The glass is only partially thawed, indicating that some of the filaments have broken.

Power check

To diagnose an open circuit, you need to know. In DCV (DCV) mode, you need to check sequentially to see if voltage is being applied to any of the pins.

To check the power supplied to the relay, it must be removed from the mounting block. To check, you need a multimeter (in constant current mode, up to 20 V) or a test. Turn on the heated rear window. If there is current on the 85 and 86 pins of the relay, then there is a malfunction in the relay itself or in the subsequent elements of the circuit.

To check the performance of the relay itself, it must also be removed from the unit.

You can use the multimeter in resistance measurement or so-called continuity mode. Illumination of different bulbs helps to identify + and -; some devices have a soundtrack.

To check the coil located in the relay, connect the probes to pins 85 and 86. If the multimeter shows infinite resistance, and the red indicator does not light up in the control, indicating a short circuit, then the coil has burned out or the contacts are soldered. For further verification, connect power from the battery to the 85 and 86 pins. After a click, indicating that the coil is working, contact should appear between pins 30 and 87.

If you do not want to test separately the relay and terminals 85, 86 in the mounting block, check if there is voltage at terminals 10 (Ш9) and 5 (Ш8). The presence of voltage will be the fact that the relay and the tracks of the wiring block are fully functional.

If, while searching for a malfunction, you find oxidation of the contacts, clean the surface with sandpaper or a file. The repair of the heater will be completed at this point.

Finding a break in a heating element

There are many ways to detect broken conductive filaments. For searches, you can use the multimeter in resistance measurement mode. You need to measure the resistance at the beginning and end of each strand. The value should be approximately the same. If the value 1 lights up on the screen, this will indicate an open circuit. You can connect to the battery wire leads. The multimeter must be set to DC current measurement mode. Attach the positive probe to the positive terminal of the heating element, and apply the negative one to the middle of each thread. The value should be equal to half of the battery charge.

To localize the place, measure in the same way, starting from the edge of the thread. Place the probes at a distance of, for example, 10 cm and work your way to the edge of the thread. In order not to damage the tinting excessively, you can solder needles to the leads of the probes. This will allow you to discreetly pierce the film without harming the threads themselves.

DIY repair

Rear window heating repair is impossible without a special conductive compound. Special glue can be used to attach the terminals to the element. There are special repair compounds for the restoration of threads. Their cost is quite democratic, and you can find them in almost every department of automotive supplies. There are also methods for self-manufacturing conductive compounds. Heater repair is as follows:

• remove the tint from the break. Use a ruler and a clerical knife to carefully cut the film only along the perimeter of the thread break;
• degrease the surface;
• stick the masking tape, leaving a place inside for the repair compound;
• apply conductive glue;
• tear off the tape. Do not wait for the composition to dry, as there is a possibility that the layer from the repair area will subsequently come off along with it.

Do not apply too thick a layer, as this will reduce the resistance and, as a result, the temperature in the repair area.

A heating element repaired in this way will continue to serve you faithfully.

The current in the car is supplied from the positive one through the ignition switch, as well as through the fuses. Then the voltage passes to the heater switch and connects to the car body to the Minus battery. One of the wires of the heated glass system is also connected to the body.

When the driver presses the system power button, voltage is applied to the relay. It works, power contacts close. The current enters the heaters, passes through the heating filaments and then goes through the body to the battery.

Heating element device

The heating element has the following device. There are busbars on the sides of the rear window. They are connected with special threads made of materials with high resistance. The resistance of each strand is 10 ohms.

Their number depends on the size of the glass. So, each thread is a separate element that works separately from the others. All elements are connected to each other in parallel. This arrangement allows the system to be highly reliable. So, if one thread breaks, all the others will work.

Typical malfunctions

Before repairing the rear window heating threads with your own hands, you need to find out the malfunctions. Depending on what kind of malfunction manifests itself externally, it is possible to diagnose the operation of the system even without a multimeter.

It should be noted that it is possible to start glass heating only if the ignition is turned on. On some car models, you can turn on the glass heating only when the engine is running. This is done in order to reduce the load on the battery. The system needs from 10 to 25 A of current for full operation.

Heating does not turn on

So, if the system does not turn on from the corresponding button, the corresponding fuse may have failed. The button may also be broken. If the operation indicators light up, but the glass does not sweat, the repair of the rear window heating filaments should be started by checking the connectors and relays. In this case, according to the electrical circuits, they find where the parts are installed and change them.

Slow sweating

Sometimes it is possible to observe cases when a considerable amount of time elapses between pressing the button and turning on the heating system for defrosting the glass. If the air temperature is low or frost overboard, then the cause of this problem may be in poor contacts on one of the connectors. The resistance at the contact increases, the current becomes lower, the power decreases.

To check this malfunction, you must use a multimeter. Change the voltage at the terminals of the heating system and battery. These voltages should not be different.

Streaks remain on the glass

This is the most common problem. The problem is related to the breakage of the threads that are applied to the glass. This malfunction can be diagnosed by the stripes on the glass after turning on the system.

The threads on the rear window are of low strength. And if you mechanically act on them even a little, then you will need to repair the rear window heating threads.

Determine the place of the cliff

Finding a break is not difficult. Condensation or permafrost will not disappear near the thread. That is why, in order to quickly find the damaged element, the threads are counted and then find the damaged place. But sometimes the cliffs are so insignificant that it is very difficult to notice them. Then a voltmeter should be used.

Due to the fact that one of the buses is connected to the car body, the negative wire of the multimeter is connected to the body. Next, the positive wire with the probe touches the first and second busbars. On the first, the voltage is +12 V, and on the second - 0 V. If for some reason there is no access to the tires, then measurements can be made where the threads come out from under the seal.

If the heating is on, there is 12 V in the system, but the threads do not heat, then this means that all the wiring to the first bus is in working order. If there is no voltage, then this indicates poor contact. It is required to repair the threads and contacts of the rear window heating. The relay may also fail.

If there is voltage not only on the first, but also on the second bus, then they are looking for bad contacts in the circuit connecting the wires of the heating system to the ground.

How to find a cliff

The filament is a 10 ohm tape. The voltage will be different in different places. At the first point, the voltage will be 12 V, at the third - 6 V, at the fifth - 0 V. If you do not know which of the threads is damaged, it is easy to find it. To do this, measure the voltage in the middle of each strip. If the thread is broken, then the voltage will be either 12 V or 0. Therefore, the break is on the left or right.

Repair

There are several ways to repair this system. The most efficient and fastest way is to use a heated rear window repair kit.

There are many of them, they are designed to restore the integrity of the tapes. This set has it all. It is a syringe with a special paste. Reviews characterize Permatex well. Repairing the rear window heating filaments with it is very easy and simple. You don't need any additional tools. Everything is in the set.

So how do you make a repair? Everything is very simple:

• Using alcohol or a solvent, we clean the glass area at the point where the thread breaks.
• We take scotch tape in our hands and glue it on both sides of the heating element. In this case, the distance between the tape should not differ from the thickness of the heating thread.
• Using a brush or syringe, apply conductive glue or paste (depending on which set will be used). How to apply it? The glue should cover the whole part of the thread, 10 millimeters on each side.
• Remove the tape and wait for the glue to dry. According to the instructions, the composition dries up in 24 hours.
• After a day, remove excess glue. This can be done with a sharp knife - kitchen or clerical. Be careful - the knife can easily damage the surface of the heating element.
• We wipe the glass with a soft and slightly damp cloth.
• We check the performance of the element.

You can also use another remedy to repair the heated rear window threads. This is "Elecont" of domestic production. The mass is applied to the place where the thread is broken. Apply glue so that it overlaps the whole part of the thread on each side. After hardening, the electric heating system will work again.

It is believed that the glue can be made by yourself (from metal shavings). But you shouldn't do that. The finished product is much more effective. In addition, the reliability of the self-adhesive manufacturing technology has not been confirmed.

Conclusion

So, we found out how the heating threads are arranged and how to repair them. The difficulty of repairing is finding a broken tape. After all, the system will work even when half of all available threads are broken. True, the glass in this case will fog up by half.