7 Most Common Electrical Problems in a Car

If you have difficulty starting your car, or if your dome lights begin to dim or flicker and other accessories do not function as usual, you might be dealing with an electrical problem. An automobile is a maze of wires, fuses, plus a host of electrical components, and in case one of these parts malfunction, it can result in poor performance and efficiency, or worse, your car might not start at all. As basic car maintenance, you must learn the most common electrical car problems and how to fix them. 

Most Common Electrical Problems and How To Fix Them

Dead or Faulty Battery

The most common electrical problem, and a major problem at that, is a dead or faulty battery. The battery is usually the very first thing you need to inspect if you have difficulty starting your car, or if your car has no power and refuses to start altogether. 

Upon startup, the engine pulls amperage from the battery. Therefore, if the battery is depleted or it’s approaching old age that it does not have enough power to do its job properly, the engine would usually take longer than usual to get fired up, if at all. One of the most common scenarios  of a weak or old battery is if you hear the engine cranking slowly.

car electrical problems
The most likely culprit of a hard starting problem is a weak or dead battery. Photo credit: Liberty Collision

Another version of a hard-starting problem is you don’t hear the engine crank at all, but a rapid clicking sound instead. This happens when the battery is either almost or completely dead, so there’s too little available power to even crank the engine. Or if you hear a slight click and the engine still won’t start, your battery might be faulty or it isn’t receiving a proper charge from the alternator, which is another common electrical problem with the alternator.

Another telltale sign is many electrical accessories not working properly at all at the same time. Do note that if something doesn’t work but others still do, then the issue often lies with the malfunctioning accessory instead of with a dead battery. When the battery’s weak, it cannot provide power to operate these features. This can include dim headlights, or the dashboard gradually dims while the car’s running, or a buzzing radio noise through the speakers, and more. 

Hard starting problems are typically more common in the winter. Extreme cold puts car batteries under additional stress. While younger batteries under 3 years old have higher resistance to extreme cold, a battery loses its strength with old age. So if you live somewhere that frequently gets below freezing point in the winter and find your battery dead one morning, this often suggests that the battery is old enough to require replacement pretty soon. 

You should avoid repeatedly deplete your car batteries too deeply before recharging it. Over time, too many deep discharges would make the battery deteriorate faster and thus come to the end of its lifespan faster. And batteries are not cheap to replace.

Power stored in the battery at a certain time is measured in voltage and this shows how healthy and functional your battery is. To keep track of your battery’s health and know when it’s time for a new one, you will need a multimeter or a voltmeter to measure the voltage in your battery. A battery is fully charged when it holds 12.6 volts or above. When a battery goes down to 12.2 volts, it is only 50% charged. At 12.2 volts and below, a car battery is considered weak and should be charged to be restored to a full charge.If a battery holds 12 volts, it is considered “dead” and needs to be replaced. 

Another reason to keep your battery sufficiently charged is when the battery is depleted, the alternator and the starter motor will draw excessive voltage to compensate, thus they will be overworked. If this repeats, they will malfunction and needs to be replaced prematurely.

Other Battery Problems

Other common battery problems are loose battery terminal connections and corrosion on the terminals. The battery can only do its job properly when all connections are intact. Corroded or loose terminals, frayed or damaged cables can limit the alternator’s ability to charge the battery and provide power to start your car.

These electric problems can cause weak or no cranking, dim dash lights and dome lights or malfunctioning electrical accessories, and no ignition. Thus, they can be confused with a dead or weak battery and might cause the owner to replace a new battery without any need. Therefore, before you make any expensive replacement, it’s a good idea to inspect the battery for loose or corroded terminals. 

Corrosion is a natural occurrence with all types of automotive battery due to the chemical reaction that goes in the terminals and battery cable ends. Car battery corrosion looks like a crusty, ashy substance that forms around the battery ports and is either white or green in colour. 

Another corrosive process called “sulfation” will typically form white sulfur crystals on the negative battery terminal and happens when a battery is undercharged, either because the car’s only driven for short trips, so the alternator doesn’t have sufficient time to replenish the battery, or simply because the battery is too old and cannot hold a charge properly. In contrast, if sulfur crystals build up around the positive electrode though, the alternator is overcharging the battery.

Fortunately, tightening loose terminals and cleaning up corrosion is simple. First, disconnect the negative cable and then the positive cable. Apply a mixed solution of baking soda and water or a commercial cleaner for this purpose to the terminals, then use a detailing brush or old toothbrush to scrub away the accumulated corrosion. Wipe clean and let dry completely.

If the terminals or cables are severely damaged, you’ll have to make a replacement. Also, look for dried, cracked, and peeling insulation, which is the plastic or rubber cover on the cable and check if the copper strands are intact, and replace them if needed.


Damaged or Broken Alternator

If the hard starting problem happens when the engine is hot, that is when the car has been running, especially if you have made inspection and determined that your battery is still young and in good shape, then the alternator would be the most likely culprit.

The alternator is a car’s charging system. It produces electricity from the car’s mechanical energy to charge the battery, as well as to operate various electrical parts such as dash lights, dome lights, the stereo, and the A/C. Optimal performance from the alternator means that the lifespan of your car’s battery is maximized. Either undercharging or overcharging would be detrimental to your battery life.

Note that other than a faulty or damaged alternator, a hard starting problem might be caused by a damaged alternator belt, so do check if the belt is intact and replace it if needed.

You should test the alternator regularly together with your battery, say every 4-6 months using a multimeter. To test an alternator, you must test the battery first. This is because the battery gets the car started; when the car runs it spins the alternator and this spinning keeps the battery charged. If the battery is too weak, it will not get the car running and thus the alternator cannot be tested. 

Testing an alternator is the same process as testing how much voltage a battery stores. Remember to leave the engine running, turn off all electrical accessories that may be using electricity. A healthy alternator should produce between 13.1V and 14.6V at regular idle speed. Anything lower means your car’s undercharged, or if higher, overcharged, both of which are unhealthy for the battery and your vehicle’s operations. 


Faulty Starter

After a weak or dead battery and a faulty alternator, the next likely electrical mishap that is causing a slow starting or no starting problem is the starter motor, which might need to be repaired or replaced.

The starter motor is part of an electrical circuit that sets the engine in motion, thus its name. It needs to receive electrical current from the battery to do its job. It’s very easy to diagnose a faulty starter. As the starter is responsible for kickstarting the engine, you won’t hear that click noise when you turn the ignition key. 

If this happens, check if anything is obstructing the flow of electrical current to the starter motor. Check the joint of all the cables between the starter and the battery for a loose connection. Tighten everything to ensure proper flow of current to the starter.

Also check for corrosion accumulated on the starter and the cable clamps and terminals of the battery. Disconnect the battery and use a fine-grade sandpaper or a brush and a cleaning solution for this purpose to remove the buildup.

Another reason for the starter not working is a stuck gear. This happens when you find the starter motor dead but the windshield wipers and headlights are working. In this case, locate the starter and give it a gentle tap a few times using a hammer or a wrench. Use a light hand and avoid damaging the part.


Failed Spark Plug 

The spark plug is another electrical part prone to wear and tear due to its extensive use. To generate a series of explosions inside the engine’s combustion chamber as a means for producing power, the spark plugs supply the electrical spark that ignites the air and fuel mixture. 

Generally, automotive spark plugs are made from durable material, and can withstand millions of explosions before needing to be replaced. That said, over time, repeated explosions and corrosion lead to smaller or weaker sparks. Automakers typically recommend that you replace your spark plugs roughly every 30,000 to 50,000 miles. Faulty spark plugs can lead to various problems including engine misfires, Check Engine light on, and hard starting problems since not all cylinders are igniting. 

The primary wear and tear to spark plugs is with the electrode. If you look at a spark plug, you’ll notice one end is bulbous, with a small metal rod coming out of the center. That center rod is the electrode, where electricity arcs from that to the hook.

Through normal use, the electrodes become worn to the point that the gap between the two leads begins to widen. As a result, it doesn’t create as much or any electric arc. Or worse, spark plug corrodes to the point where it breaks, which would damage the interior of the cylinder and calls for an extremely expensive repair. 

When you get new spark plugs, you should also replace the spark plug wires at the same time. While you should inspect your spark plugs periodically to make sure they are intact, also inspect the wires for any frays, cracks, and even bites, since some wires are made from a soy-based material that’s a favorite snack for rodents.

Spark plugs are for petrol engines, while glow plugs are for diesel engines. Glow plugs heat up the cylinder so diesel can ignite more easily under pressure.

Although they are also made from heavy duty materials, glow plugs are essentially heaters and as with all heaters, they will eventually burn out. If one glow plug burns out, the engine will start normally and they usually burn out one by one instead of all at once, which would be a problem. 

Short Circuits

Where there is an electric installation, there is the likelihood of a “short”, or short circuit, which is a fault in the wiring harness. Short circuits are one of the oldest electrical problems in a car. 

A short can be caused by faulty connectors, damaged relays, damaged insulation on wires, damaged appliances or custom appliances improperly installed, or faulty car bulbs. Damaged wire insulation typically happens due to a pinched or damaged wire when there is some maintenance work done on the car, including simple paint jobs. 

Severe cases of short-circuits can cause a runaway electrical current that quickly overheats and burns the wiring looms and appliances. This can occur under the hood, in the trunk or cargo area, or under the instrument panel.

A short is not too expensive or labor intensive to repair, and doesn’t require complicated tools. The hardest part is locating the short-circuit, and to find it, you might need to dismantle a few parts, including the covers, trim parts, and fuse boxes. In general, you will need a systematic elimination process where you disconnect certain parts of the installation until you can pin-point the location of the short.

Blown Fuse

A short-circuit is dangerous, since they can cause burned wirings and appliances, and God forbid, might even start a fire. To avoid this catastrophe, fuses are put into the system as  deliberately weakened spots that burn out once a short-circuit or other kind of overload happens. Fuses are a vital part of any electric installation.

So they are made to burn out. But this electrical problem is easy to fix. You just have to find the burned out fuse, pull it out and replace it with a new one with the correct amperage. It’s a good idea to take note if the same fuse you recently replaced blows out again too soon after or a few times in a row, then the problem might lie elsewhere and you should troubleshoot as soon as possible.