The technology in our cars today has changed quite a bit since the invention of the automobile. From the way we start them up, to the way we drive them and service them. The majority of your car’s most overlooked capabilities nowadays are possible thanks to one simple component known as a solenoid.
Auto solenoids are essentially valves that let current pass through at a certain period or under a certain condition to enable an operation to take place. This then helps create a mechanical force that can help do some of the most basic functions in your car. In fact, this old piece of technology isn’t that complex.
What Are Solenoids Made of?
Body
The main part that makes up a solenoid is its valve body. This is the component that has both the input and output ports as well as the valve seats. Modern car solenoids have the valve body control the opening that controls the flow of electricity too, which makes them even simpler.
Coil
The coil is the electromagnet that has windings made of copper. These windings are what help actuate the plunger motion when they are energised.
Coil Housing
The housing of the coil is a cylinder made of non-ferrous metal and it’s sealed at one of its ends. This makes the channel needed for the plunger to move when the coil’s windings get charged up.
Common Types of Solenoids in a Car
Transmission
If you have a vehicle with an automatic transmission it probably has solenoids in it. Transmission auto solenoids play a vital role in the flow of transmission fluid and in regulating gear shifts.
EGR
An EGR or exhaust gas recirculation solenoid controls the flow of exhaust gas back into the engine through the EGR valve. This is done to reduce the amount of nitrogen oxide your vehicle emits.
IAC
You also have an IAC vehicle solenoid or an idle air control solenoid which helps manage the amount of air that enters the engine and its speed when idling. Simply put the solenoid helps the air enter in a way that bypasses the throttle plate.
Starter
A starter solenoid is one that helps engage the starter motor when you turn on the key in the ignition which makes the engine run.
VVT
If you have a vehicle with VVT or variable valve timing you most definitely have a VVT solenoid part of the mechanism. If you have a naturally aspirated petrol car from Toyota, Honda or Mazda you most definitely have a VVT engine under the bonnet. The vehicle solenoid in it helps control the flow of oil to the mechanism of this technology which decides when the intake or exhaust valves open and for how long.
Fuel Injector
Every car nowadays has fuel injectors and therefore it has such a solenoid too. Fuel injector car solenoids are able to open and close the injector in order to inject fuel into the combustion chamber at the right time and with the right amount too.
Turbo Wastegate
If you have a turbocharged engine instead of one with VVT you most probably have a turbo wastegate solenoid. The wastegate is what controls the amount of exhaust gas that goes to the turbocharger and for that to happen a solenoid is used in order to help control the boost pressure in the turbo.
Canister Purge
The canister purge vehicle solenoid is part of your car’s EVAP system as it helps regulate the flow of fuel vapour that goes for the purge canister to the engine’s intake manifold.
Signs of a Bad Solenoid
Sound
When your car isn’t able to start but you hear clicking sounds, then it most probably is either a dead battery or a dead starter motor. But when there are no clicking sounds, it means that you probably have a dead solenoid instead. It could also be that the solenoid isn’t completely gone but it’s just having issues that you may help it recover from.
No Start
If the engine isn’t able to crank it could mean that there are more serious issues or that the solenoid just isn’t sending the power needed for the starter motor to make the crankshaft move. Inspecting the latter first is a more hopeful approach.
Slow Start
When your car is able to start but it does so slowly it could mean that the contacts in the solenoid are burned out. This can easily lead to excessive resistance being put on the metal contacts and thus the slow crank occurs.
Spinning Motor
Other similar issues with a solenoid can result in the starter motor spinning when you try to start your car but the flywheel doesn’t. That’s mainly because the solenoid is not working and thus the starter motor isn’t engaging the flywheel as it doesn’t have enough power to do so since the flywheel is quite a heavy component, definitely heavier than the starter motor.
Australian Atlas 