A car starter solenoid is a small electric switch in the ignition system that sends power to the starter motor when you turn your key in the start position. The engine will not crank unless there is voltage going to this part of your electronic ignition, which can be caused by a bad battery or one with low cranking amps. With a bad starter solenoid, you will not be able to start your car from the battery.
If it is a weak or drained battery that has been giving your trouble starting up your engine, then a bad solenoid may drain the battery. If the alternator is charging properly and sending current out to all parts of the vehicle, then the starter solenoid should not be draining your battery.
You will want to check the voltage of your battery. Whether it is old or new is another thing you can look into with a mechanic if needed. If it continues to drain after replacing the starter solenoid, then there are likely other problems in need of fixing on your car.
Parasitic Draw Chart
|Low Parasitic Draw (mA)
|High Parasitic Draw (mA)
What happens when a solenoid goes bad?
The solenoid is pretty simple in its design. It’s a plunger that moves when the battery sends an electrical current through it to open or close whatever mechanism you need opened or closed, like your brake lights, for example. This makes it easy to see how if there was any damage at all done to this part of the car, it could be the cause of your battery woes.
It is easy to recognize the symptoms of a bad starter solenoid. If you notice that your lights seem to go on and off without any rhyme or reason, it might just be a warning sign that something is up with this part of the car. If there has been an electrical surge because of some other damage done elsewhere in your solenoid system, then the solenoid could be acting up and not working the way it should.
In order to avoid this from happening, keep an eye on your lights when you’re driving at night. If they seem to be reacting strangely, try to get them checked out as soon as possible so that there aren’t any unnecessary delays in getting moving if you need a new battery.
What can drain a car battery when the car is off?
There are plenty of reasons for this to occur, but two significant causes most often contribute. The first would be the battery itself, and the second would be a bad solenoid draining it while your car is turned off.
Other factors that contribute to a drained battery include:
- A bad alternator or voltage regulator may not send the correct amount of power to your vehicle’s electrical system, which can cause it to drain faster. This is why you should always get your car checked out by an auto mechanic immediately if something seems wrong with how fast your battery discharges while off.
- A spark can jump out of the alternator if it is faulty, which will then cause your battery to drain. This is known as a parasitic draw, and on many vehicles, this causes around 150 milliamps per hour.
- The number one reason for an increased discharge would be due to electrical problems with the car itself. If you have vehicle-related issues, then you need to get them checked out.
- Leaving the stereo or lights on while the vehicle is off can also cause a discharge.
- Faulty battery cables and corroded terminals may allow your battery to drain faster than usual, so check these things out right away if you think this might be an issue.
How do you know if your starter solenoid is bad?
It’s not always easy to tell, but here are a few things to look for:
- If you hear your engine turning over, but it won’t catch and start, or if the starter makes strange noises when you try, then there is probably an issue with your solenoid.
- Another common symptom is that your battery will be dead at random times in between driving. If your battery is new or recently tested and it’s draining faster than expected, then the solenoid could be bad and should be replaced.
The solenoid is the part of your starter system that uses an electric current to control when your engine can start or crank. Solenoids are made up of a plunger inside what’s called an electromagnetic coil, which creates magnetic fields around it. When electricity passes through this coil, these fields collapse and cause the plunger to move. When the plunger moves, it either connects or disconnects two parts in your starter system and causes a gear inside of it to turn over and start your engine.
There are a number of reasons for a bad starter solenoid. Some causes act alone, while others work together. The following are some examples of factors that can cause a starter solenoid to fail.
- Due to bad wiring – When there is a failure in power distribution, the current can either get too low or go to an unsafe level. This will make your starter system malfunction and may cause short circuits, which could lead to other problems with electrical components of the car, such as starters themselves. The terminals on these wires are left loose or connected wrongly, causing poor wiring that affects performance.
- Due to excessive moisture – Heavy moisture can cause corrosion or rust on the solenoid. This will restrict current flow, and it may result in your car not starting up when you turn the key. Additionally, if there are loose terminals on these wires, then they can get wet, which could also lead to problems with the connectivity of components inside the starter system.
- Due to the over-tightening of bolts and other fasteners – This will cause the system to not function properly and may lead to a damaged starter.
There are numerous causes for bad solenoids, but these three problems seem to be some of the most common. If you have any electrical issues with your car, it is always best practice to trust professionals who know what they’re doing so that you won’t be faced with any unnecessary issues.
When you’re not sure if the solenoid is bad, ask a professional to help diagnose and fix your starter system. Detecting the issues early on will save you money and time in the long run.
If it sounds like there’s something wrong, then don’t hesitate to contact an automotive company that specializes in car repairs and maintenance. This way, you can be sure that you’re spending your money on the right service.