- What is a starter solenoid relay?
- The purpose of the starter solenoid relay
- Design, types and features of solenoid relays
- The principle of operation of the traction relay
- Signs and causes of relay failure
- Checking the starter retractor relay
- Repair of the starter retractor relay
- Choosing a new solenoid relay
Despite the fact that most modern motorists prefer servicing and repairing their cars in specialized centers, no one has canceled independent vehicle diagnostics. In addition, an elementary understanding of the device of the machine will help to avoid deception on the part of unscrupulous craftsmen, who diagnose the missing wiring as a breakdown of a serious unit. And they "repair" this breakdown by elementary tightening of the contact.
One of the situations in which a car enthusiast should be observant is when he starts the engine. In general, this is possible if the starter is working properly. The key role in whether the internal combustion engine of the transport will start is played by a retractor or traction relay.
What is a starter solenoid relay?
This part is attached to the starter. It depends on it whether the flywheel can turn the trigger mechanism or not. As shown in the photo, the traction relay is part of the starter design.
No modern electric starter works without this element. There are many modifications of this element. However, the operation of the device is identical in all cases. The relay itself performs several functions simultaneously.
The purpose of the starter solenoid relay
Do not confuse this part with the starter relay, which is used by the ECU to activate the trigger. The traction (this name is officially used by the vehicle manufacturer in the technical documentation) is installed directly on the starter housing and looks like a separate element, but on the one hand it is firmly connected to the main device.
Solenoid relays in cars do the following:
- Provides a strong connection between the gear wheel and the flywheel crown;
- Keep the bendix in this position as long as the driver holds the key or the start button in the extreme position;
- They provide the closure of the contacts of the electrical circuit, which leads to the activation of the starter motor
- The bendix is returned to its place when the driver releases the button or key.
Design, types and features of solenoid relays
The solenoid has two windings. The most powerful is the retractor. She is responsible for ensuring that the anchor overcomes the maximum resistance of all subpurified elements. A second winding of smaller wires simply holds the mechanism in that position.
To prevent the electric motor from being blown apart when the bendix contacts the flywheel of an already running motor, most modern starters have special overrunning clutches.
Also, solenoid relays differ in the type of housing. It can be collapsible or non-collapsible. Another difference between some modifications is in the control method. The system can only activate the starter drive or together with it also the circuit in which the ignition coil or other equipment is located.
The principle of operation of the traction relay
The relay operates according to the following scheme:
- The traction winding receives voltage from the power source;
- A magnetic field of such strength is formed in it that it sets the anchor in motion;
- The armature moves the starter fork so that it engages the bendix and moves it towards the flywheel;
- The teeth of the drive wheel engages with the teeth of the rim located at the end of the flywheel;
- At the same moment, from the other end, the armature moves the rod, on which the "penny" or contact plate is fixed;
- The plate connects the contacts, which are connected to the car battery using a bolted connection via wires;
- Voltage is applied to the starter motor;
- At this moment, the retractor coil is deactivated, the holding coil is switched on for its change (it is active while the driver is trying to start the engine);
- When the key (or the Start button) is released, the voltage disappears in the winding, the springs return the rod to its place, opening the contact group, the battery is disconnected from the starter, the electric motor is de-energized;
- This time, the anchor no longer holds the starter fork;
- With the help of a return spring, the bendix is disconnected from the crown, which by that time should already be rotating due to the autonomous operation of the internal combustion engine.
This is how the classic traction starter works. Depending on the functionality, the device can connect additional equipment to the circuit, for example, an additional relay or an ignition coil.
Signs and causes of relay failure
The very first symptom of a traction relay breakdown is the inability to start the engine. However, strange sounds may be heard from the trigger. You don't need to be a professional mechanic to diagnose a broken starter. Turning the key will either not start the car, or it will take several tries. Sometimes it happens that the engine is already running, the key is released, but the bendix wheel does not detach from the ring gear.
There are not so many reasons for traction breakdowns. Two of them are mechanical - the bendix return spring has broken or the overrunning clutch has jammed. In the first case, the gear will not mesh well or will not disengage from the rim. In the second, the pull-in winding does not have enough power to overcome such resistance. As a result, neither the motor is spinning, nor the bendix extends.
The rest of the faults are associated with the electrical circuit, so to find out what the problem is, you need to arm yourself with the appropriate tools.
Checking the starter retractor relay
The retractor may have several breakages. They can only be removed after the device has been disconnected from the motor. But before you can do this, you need to carry out a few simple procedures. They can eliminate a "symptom" very similar to a starter failure.
So, here are these simple steps:
- We check the battery charge - if the starter clicks, but the flywheel does not turn, then there is simply not enough energy;
- Electricity may not flow to the terminals due to oxidation at the battery terminals or other wire connections. Oxidation is removed and the clamps are more firmly fixed;
- Check the starter relay to see if it is working properly.
If the malfunction has not been eliminated by these actions, the mechanism is removed from the machine.
Starter dismantling procedure
First, the car must be driven into a pit, lifted on a lift or taken to an overpass. This will make it easier to get to the starter mount, although in some cars the engine compartment is so large that access to the starter is possible even from above.
The starter itself is removed quite easily. First, unscrew the contact wires (in this case, they must be marked so as not to confuse the polarity). Next, the mounting bolts are unscrewed, and the device is already in the hands.
How to check the starter retractor relay
The functionality of the retractor is tested as follows:
- The positive contact of the device is connected to the "+" terminal on the battery;
- We fix the negative wire to the negative terminal of the battery, and close the other end of this wire to the starter case;
- A clear click from the device indicates the correct operation of the traction relay. If the starter does not start the motor, then the problem must be looked for in other nodes, for example, in the electric motor of the starting device;
- If there is no reaction, a breakdown has formed in the relay.
Repair of the starter retractor relay
Most often, the traction relay is not repaired, since its elements are mainly enclosed in a non-separable case. The only thing that can be done in this case is to carefully remove the cover rolling with a grinder. A contact plate is located below it.
Often the fault lies in the burning of the contact surface. In this case, the plate and contacts are cleaned with sandpaper. After repair work, the body is carefully sealed.
A similar procedure is performed with a collapsible modification. The only difference is the principle of disassembly and assembly of the structure.
If everything is in order with the contacts, but the traction does not work, then, most likely, there is a problem with the windings. In this case, the part is simply changed to a new one. Repair of these elements is extremely rare, and then only by hand-made lovers.
Choosing a new solenoid relay
Finding a new retractor to effectively start the powertrain is not the most difficult task. The selection is made in accordance with the manufacturer's recommendations. In the store catalog, the company can offer different options for a particular starter.
You can also dismantle the starter, bring it to the store. There, experts will help you choose the right modification.
First of all, the choice must be stopped on the original spare part, even if it is not manufactured at the factory where the car was assembled. Basically, car manufacturers are engaged only in assembling vehicles, and spare parts for them are manufactured at other factories and, most often, by other firms.
It is worth considering that retractors are not interchangeable for different starters. They differ from each other not so much in design as in drive power and the principle of circuit connection. For this reason, you should be careful when choosing a new part.
Among the products that are sold in retail outlets, you can often find the desired position on which the stamp of a certain company is located, but the small print may indicate that this is a packaging company, and the manufacturer is completely different. An example of this is the products of the Cargo company. This is a Danish packing company, but not a manufacturer.
Among the leading manufacturers of high-quality retractors are:
- European manufacturers - Bosch, Protech, Valeo;
- Japanese firms - Hitachi, Denso;
- And one American manufacturer is Prestolite.
Choosing products that have a high level of quality, the car enthusiast will make sure that the power unit of his car can start at any time. If the battery is charged, of course, but that's a topic for another review... In the meantime, watch a video on how to repair a traction starter yourself: