The glow plug relay is one of the most important parts of a diesel engine, without which it is unlikely to be able to start it, for example, in cold weather. This relatively small part, which today works in tandem with the ECU, is rather an assistant in normal engine starting, but it cannot be discounted. Let's figure out how a car glow plug relay works, how to diagnose its failure and how to select it if necessary. We will also touch on issues related to replacing this relay itself.
Where is the glow plug relay located?
For each car model, the location of such a part is individual. Most often, the component, which, by the way, looks massive and is much larger in size compared to other devices, is mounted in a niche under the dashboard of the car.
However, it is worth repeating that such an arrangement is not at all necessary. Each manufacturer arranges the device differently. In order to find out where the glow plug relay is located, you need to refer to the technical documentation of the vehicle.
Replacing an element
When the test shows that the device is not functioning, it needs to be replaced. Even a less experienced car enthusiast can do this. To do this, you will have to disconnect all the terminals from the part and take it out. Then it is important to clean the place where the device was removed. Then you need to carefully unscrew all the spark plugs. Next, carry out the entire process in reverse order, only with a new block: screw the glow parts into the new block, install it in a previously cleaned place.
The location of the candles is shown by red arrows
After this, you should try to start the engine. If this does not work, then you need to check whether all terminals are connected. If everything is installed correctly, but the engine still does not start, then the problem was probably not in the glow elements.
It is important to note that different vehicles may require different types and models of glow elements.
Owners of cars running on diesel fuel should prepare in advance for the cold season and check the functionality of the relay. It is also worth keeping control over the candles themselves. It is especially important to check the performance before a long journey. Otherwise, the trip may be disrupted and postponed until the problem is resolved.
Diagnostics
How to check the glow plug relay? Based on the above, it should be noted that failure of the relay, like any other part, is not at all a desirable phenomenon. If this situation occurs, diagnostic measures must be carried out to identify the exact location of the malfunction. The cause of device failure may be hidden both in the relay itself and in the glow plugs or wires.
The relay contains contacts from the coil winding and control contacts from the control unit. For diagnostics, it is necessary to remove the part of their terminal block and apply electrical voltage. To help, you should use a device to measure it. If everything is in order, the contacts will close. For monitoring, a light bulb is connected to the relay. Also, when voltage is applied, a clicking sound occurs. If there are no signs of contact closure, then the relay coil has failed.
What is important to know
A car engine works in tandem with a large number of elements. Undoubtedly, one of the most important is the electronic control unit. It is he who calculates the time that the candles should work. The ECU is guided by readings from the temperature sensor. The relay, in fact, is located between the ECU and the glow plugs themselves, so as soon as one element malfunctions or fails altogether, the entire chain collapses. But here, too, not everything is so simple. Let's figure it out.
Modern diesel cars use what is called two-stage heating of the pre-chambers . Of course, it is gradually being replaced by a single-stage one, but since the system is still relevant, it would be useful to know why spark plugs may not work properly. Look here:
- At the 1st stage, the spark plugs receive power from a voltage source of about 11-12 Volts . When the spark plugs warm up, this voltage drops to 9 Volts. The first stage is before starting the engine. When the engine can be started, the warning light on the instrument panel goes out. You can move to the second stage;
- Already at the 2nd stage, the voltage decreases noticeably: 5-7 Volts . The temperature of the spark plugs, of course, is lower - now they only maintain the stability of the engine before it reaches the optimal temperature.
Spare parts for Volkswagen golf
Glow plug relay
GOLF III hatchback (1H1) (08.91 - 07.98)
Spare parts for Audi 80
Glow plug relay 80 sedan (89, 89Q, 8A, B3) (06.86 - 10.91)
We considered it necessary to note all this for one simple reason: if the ECU malfunctions or if the standard relay was replaced with an unsuitable one, the normal operation of the spark plugs is simply impossible. If the relay does not work, then the spark plug does not work either - during periods of severe cold, this puts an end to any attempt to start the engine.
We will continue to study the system so that the car enthusiast in the future will clearly know what the problems in the fuel heating system are associated with. Between the relay and the glow plug there is a current-limiting resistor - the most common resistor that prevents the plug from failing under the influence of overcurrents. The resistor is also connected to the motor control unit (it would be more correct to say that with a separate current sensor on this unit), and based on its serviceability, the unit judges whether the glow plugs are still working. When replacing glow plugs, inexperienced or inattentive repairmen forget to connect the wire from the current-limiting resistor to the ECU. For this reason, the entire glow plug system fails.
Location in a Ford Transit car
The glow plug relay in the Ford Transit is located in the engine compartment. To be more precise, in the front safety block. Its connector is similar to the one installed on the domestic Gazelle, so if necessary, a spare part from a domestic car will do. For long-term driving, when replacing the glow plug relay, you need an original spare part.
Many car owners complain about the quality of insulation of their original wires. In theory, they can be replaced, for example, with Chinese or Turkish ones. But the main thing is not to disrupt their connection diagram. Otherwise, the engine will become or stop functioning altogether in the winter season.
Why check the performance of glow plugs and relays?
Glow plugs are located directly in the combustion chamber. They provide heating of the fuel so that ignition is as smooth and clear as possible. We can say that they are a pre-starting device for the engine. Their performance is especially important in winter. Due to a malfunction in the glow parts control unit, the driver simply will not be able to start the engine.
They are made from different materials. They may have a closed or open heating element. Their control circuit takes into account fuel temperature, air heating, and resistance changes. When the engine does not start, many drivers initially check this particular system.
There are many reasons why spark plugs can fail. This is the expiration date of the element, the weather conditions of the region in which the car is used. The cause of the problem may lie in electrical wires or other system components.
Location of the part on the Opel car
The part responsible for starting the engine in cold weather on Opel cars is located under the battery platform on the left side. In order to repair or replace the glow plug relay on an Opel, it is necessary to dismantle the fuel filter, the safety block and the battery platform itself. If access remains difficult, you will have to remove the bumper and left headlight.
When replacing a burnt-out glow relay, you should install an original part or a high-quality analogue. Cheap fakes will not last long and reliably. Their use will sooner or later lead to failure to start the diesel engine in cold frosty weather.
What is it for
It's no secret that today the most common internal combustion engines run either gasoline or diesel. Gas-cylinder installations are gradually gaining popularity, but since they are not the topic of our discussion, we will leave them for later. So, the main executive component of the car ignition system is presented today:
- Glow plug in diesel engines;
- The spark plug, respectively, in gasoline engines.
The principle of operation of a spark plug can only be described as “the formation of a spark at a strictly defined point in time.” The spark plugs of diesel engines are not so strictly tied to time - the fuel, when compressed, begins to ignite spontaneously. However, another problem arises: spontaneous combustion does not always occur when it is needed. This is where glow plugs are needed. They heat the fuel mixture to the optimal temperature for engine operation and make its further combustion process stable and predictable. However, another problem appeared!
As a diesel engine operates, its individual components become very hot. Increasing temperatures also have a detrimental effect on the fuel. There are often cases when it begins to burn even before it gets into the cylinder, where the heat of combustion will be used to perform work. The weak link is the glow plugs - if they heat up too much, they destabilize the operation of the entire engine. To solve this problem, engineers introduced special relays.
A relay is an electrical device that can close or open a circuit in the event of a change in some controlled quantity . With the glow plug relay, everything is very simple: when the glow plug needs to work, it allows the action of current, but when the spark plug needs to “cool down,” the relay opens the circuit. This chain will be looped until the driver turns off the engine.
By Mercedes car
The glow plug relay block on a Mercedes is located under the battery platform, just like in Opel cars. If this part fails, it must be replaced.
During the repair process, it is worth considering not only the manufacturer of the spare part, but also the type of spark plugs that are installed on the car. If they are ceramic, then the relay for metal spark plugs will not function.
Of course, you can also repair spare parts yourself, for example, replace burnt wires with new ones. Or install another switch. But these manipulations can only aggravate the situation and lead to serious problems with the car’s electrical system.
Relay operating principle
The principle of operation of the glow plug relay is to control the voltage supplied to the glow plugs and the ability to regulate it. The device also controls the heating duration and temperature. The performance of the part directly depends on the readings of the crankshaft speed sensors and coolant temperature.
Modern diesel devices are designed in such a way that heating is carried out not only before starting, but also after the engine starts running. This allows you to reduce noise when the engine is running and significantly reduce harmful emissions into the atmosphere.
How does ignition occur in a diesel engine?
Glow plug relay on Volkswagen
The device on Volkswagen cars is located behind the fuse box, which, in turn, is located in the vehicle interior under the dashboard on the driver’s side. In order to dismantle the glow relay, this mechanism must be removed. These actions are carried out in the following sequence:
- The safety block is removed from the mountings.
- Rotates counterclockwise.
- In the depths of the structure there are fuses and filament relays.
The above actions apply not only to Volkswagen cars. When replacing a glow relay, it is necessary to take into account the country and company that produced the replacement part. Chinese fakes will not last long, and their use can lead to more serious damage.
Why is it sometimes necessary to check glow plugs and their relays?
Glow plugs are located in the combustion chamber. The main purpose of this element is to heat the fuel for clearer and smoother ignition and interaction with the engine. All of them are divided into two types: with an open and closed heating element. At their core, they are part of some engine pre-start device. These elements are especially important in winter; it depends on them whether your car can start or not.
The candles themselves are made from a variety of materials. Their control circuit takes into account both the temperature of the air and fuel, and changes in their resistance. It is very easy to determine if this element is faulty: your car will most likely simply not start. Experienced car enthusiasts, first of all, when they cannot start, look at the condition of the spark plugs. There are plenty of reasons why they become unusable.
The very first and main factor that goes against these details is time. Every little thing has its own expiration date, and this also applies to glow plugs. They last approximately 3 years. Everything, of course, depends on the car, driving experience and weather conditions. Yes, it is weather conditions that can negatively affect the service life of these incandescent elements. And in our harsh weather conditions, not only candles, but also the cars themselves very quickly become unusable.
Change the spark plugs on average once every 3 years; most likely, other problems can then simply be avoided.
Tips for choosing a part
The glow plug relay is a part that, if it fails, makes it impossible to start the engine in cool or frosty weather. Therefore, if the device burns out, it must be replaced with a new one. When purchasing a relay, you must adhere to the recommendations below.
What should you pay attention to when choosing a glow plug relay? So:
- Country of origin and company.
Before purchasing a new spare part, you must find out what brand the burnt part was. This will help you purchase an original part or a high-quality analogue. It is worth noting that you should not try to install relays from other models. Each device functions in connection with the design features of the car brand for which it was created. If you install, for example, a relay from a Gazelle on a Ford, then in the best case it will burn out quite quickly. And at worst, it will lead to malfunctions associated with the electrical supply of the entire unit.
- Relay type.
Relays have many typologies. One of the main criteria for separation is the area of their application for steel or ceramic glow plugs. When purchasing a new glow plug relay, you need to pay special attention to this. If you purchase a part designed for steel spark plugs when ceramic spark plugs are used in the car, then such a relay, accordingly, will not function. The same thing will happen if you put a spare part for ceramic spark plugs on a model with steel ones.
- Cost of the mechanism.
The price of original spare parts and high-quality analogues is quite high. However, it should be understood that in return the motorist receives a fairly reliable relay that will not fail in a difficult road situation. Using low-quality cheap Chinese counterfeits will lead to a loss of time, and this is at best. In the worst case, the car may stall while driving, and this, accordingly, will lead to a dangerous situation on the road. Also, a low-quality relay can cause more serious damage to the car.
Changing the filling of the glow plug relay
Replacing a relay is a fairly simple process and can be done by absolutely anyone, even those who have looked under the hood of a car for the first time. It is necessary to disconnect the relay, as was done in the test description, that is, disconnect all the terminals and carefully remove the relay out. Then it is advisable to clean the place where it was installed, as well as the part itself, which you have already successfully removed. After you have finished wiping, slowly unscrew the spark plugs from the relay. It is best if you work with special gloves.
Then, with a rag, we remove excess dust in the holes where the glow elements were installed, and begin to smoothly screw in the new spark plugs already purchased for your car. This fact needs to be noted: each car has different types and models.
You should consult your dealer when purchasing these parts. After you have screwed in the spark plugs, install the relay in place and try to start the engine. If your car does not want to start, check that you have connected all the terminals. If your car does not start even after checking, then most likely the problem was not with the spark plugs.
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Checking the glow plugs yourself
This is often done by visual inspection. This allows you to identify malfunctions and irregularities in the operation of the fuel system, the condition of the piston group, and the correct operation of the electronic control system.
Defects on the spark plug
If the spark plug has not yet exhausted its working life, but upon visual inspection there are cracks and swelling in the middle of the body, then this indicates:
- increased voltage supplied to the spark plug. In order to clarify this fact, you need to measure the voltage supplied to the spark plugs by the on-board network using a multimeter;
- The glow plugs do not turn off for a long time. You can check this using an ohmmeter or by noting the response time of this diesel engine ignition element by clicks.
There is melting at the tip of the candle
It can form for the following reasons:
- premature fuel injection occurs;
- the nozzles are dirty, so the spray is not carried out correctly;
- overheating as a result of late ignition and weak compression;
- The pressure valve has failed. You can check by loosening the nut of the fuel line that goes to the injector. If this is so, then it will not be foam that will come out from under it, but fuel.
When examining the candle, pay attention to its thin part. It should not be melted, otherwise you need to prepare to replace it, even though it still works.
Removing the spark plug relay on the YaMZ-5340 engine
1. Disconnect the preheater wire terminal from the spark plug relay contact by unscrewing the terminal securing nut;
2. Remove the spark plug relay (1) (650.3740062) by unscrewing the 2 M6 bolts (2) securing the relay.
