Car electrical problems have been around almost as long as the car has.

Although electricity has played a major role in modernizing the car, vastly improving the driving experience and making the car usable in all conditions, car electrical problems have given a lot of headaches to car owners.

You see, an electric installation, by default, will best function in a stationary environment. The car is the exact opposite.

Heat, cold, moist, filth, vibrations are just some of the causes that spell doom for a car electrical installation. Combine this with an expectancy from the end-user (driver) for everything to work flawlessly for a long period of time (at least 10 years) and you’ll get a good picture of what kind of task every car manufacturer has in front of them.

In this article, you’ll see what are the most common car electrical problems and, perhaps, give you a clue what may be wrong if you encounter these kinds of problems.

We’ll start from the most frequent ones and finish with the rarest.





Car batteries have a “life-span” of their own. They usually last for about five to seven years if all the conditions are right (alternator voltage output, electric installation or else). It also depends on the build quality of the car battery.

Car batteries rarely die on you at once. It’s mostly a slow and gradual procedure where the first tell-tale sign will be occasional weak cranking which will get worse, for sure, once winter starts and the temperatures go down.

Winter is the most critical season as low temperatures additionally stress the car battery.

The worst case scenario is a totally depleted car battery which won’t be able to even start the ignition.

Weak car batteries can also cause car electric problems that may seem non-related to this problem; namely problems with the car electronics.

Today’s fragile car electronics are highly dependable on a stable power supply. If it fluctuates, you’ll get faults that you may think are caused by other things like faulty sensors, bad connections or else). It can send you on a wild goose chase in no time.

These sort of car electric problems are best solved by replacing the car battery.  Some sort of revival is possible if the car battery is not totally damaged. Pouring in new electrolyte and recharging the battery, for instance, can help.

If you want to learn how to replace a car battery, click here for a separate article on that topic.



loose-corroded-car-batttery-terminals-15-most common-car-electrical problems

When mentioning the car battery, one more common electrical problem is corrosion or filth on the battery terminals.

Overtime, a layer of green-like, dusty substance starts to appear on the terminals. This is because of chemical reactions as most of battery terminals and the battery poles are made of lead. This can also happen if the alternator voltage output was too high in some period of time.

Besides this, overtime, a thin-film can form between the battery poles and terminals.

In any case, these car electric problems can be confused with a dead or weak battery thus causing the owner to replace a new battery without any effect.

The solution to this problem is simple, take off the battery terminals (minus first, than plus) and thoroughly clean them with sandpaper, a file, solvent or else. Use whatever you have or suits the situation best. Main point is to have a squeaky clean connection between the battery terminals and poles.

In more drastic situations, where the battery terminals are severely damaged, you’ll have to make a complete replacement. Not a complicated job and one that you can do for sure.

About loose battery terminal connections: they can cause a false alarm (like weak or no cranking, no ignition, no dash lights etc) and lead you to replacing the car battery without any need. The remedy here is cleaning first and then properly tightening the battery terminals.




Fuses are a necessary part of the electric installation. They are deliberately weakened spots on the installation that burn out once a short-circuit or other kind of overload happens.

This way the electric installation and appliances are safe from major damage or even, God forbid, a fire.

Burnt out car fuses are simple car electric problems to solve. You have to find the right fuse and simply pull it out and insert a new one.

If you want to learn how find and replace a blown car fuse, click here for a separate article on that topic or watch a video tutorial on our You Tube channel.

Just make sure that you always replace the correct fuse in terms of correct amperage. If the fuse blows out again or a few times in a row, then you probably have a bigger problem that you should check out as soon as possible.




Electric installations are highly dependent on a good “flow” of electricity. Every electric installation has to be interrupted at some point and then connected again. This is to insert things like switches, fuses, relays, appliances or else.

Every such spot is a possible weakness in the installation which is, over time, prone to failure.

Regarding car electrical problems, most faults come from corroded or loose contacts (like corroded or loose screws or nuts that hold contacts, corroded or loose connectors etc).

Although most types of electrical connectors are insulated and protected very good in today’s cars (plastic and rubber protection) over time moist and filth can get inside and cause corrosion.

Constant vibrations that are always present are also one of the main causes of loose contacts.

These car electric problems are solved by cleaning or completely replacing connectors, contacts, components etc.



Ground connection is one more major factor that mostly everyone overlooks when it comes to car electrical problems.

It’s the connection that starts from the minus (-) battery terminal and continues on to the car body, engine and gearbox.

As mentioned, electric current on the car depends on proper “flow”. It goes from plus to minus and circulates inside a closed system. Without a good ground connection, the flow is interrupted.

A simple fault like a rusty screw or washer, loose screw (nut) or a corroded connector can cause serious problems (like overheating of the car installation, weak cranking, ECU problems and much more).

Have in mind that there are numerous ground connections on the car (besides the main ones that lead from the battery to the car body, engine and gearbox).

They can be in hidden places, so if you encounter this problem, best perhaps Google the exact locations and give them a check.

Repair of these kind of electrical problems is simple: once you find the location, unscrew or loosen nuts, washers or connectors  that hold the wires or cables in place and give them a thorough clean with sandpaper, WD-40 spray, contact spray or else. After that, tighten firmly.



Car electric problems regarding broken or damaged wiring are one of the easiest to repair but most complicated to find.

Just have in mind that most cars have hundreds of meters of wiring in them! If one is broken or damaged it can be like searching for a needle in a haystack.

These types of car electrical problems may be very hard to find, even painstaking. Usually involves taking of plastic trimming, plastic covers, wire looms, connectors etc. On this part, a huge amount of patience is necessary.

Broken or damaged wiring can cause problems that may be attributed to other things (like sensors, switches, relays or else). This can easily send you on a wild goose chase and cause unneeded expenses.

When solving this problem, some knowledge of the car electric installation will come in handy. There are also tools that can help with these car electric problems (detectors of broken cables for instance).

It can be solved, if with nothing else, then with bypassing parts of the installation that are broken or damaged.




Car bulbs are one of the most common car electric problems. As with every bulb, they have a life-span of their own and are meant to be changed after some time.

The ones that usually go first are the ones that are used the most (low beam headlights, high beam headlights, position lights etc).

On most cars the replacement procedure is simple and quick to do. The most important part is to buy the same light bulb, especially in terms of correct voltage (12 V or 24 V are most common).

If you want to learn how to change a car headlight bulb, click here for a separate article on that topic.

Also, you can watch a video tutorial for both this and how to replace a rear car bulb on our You Tube channel.

Some cars, on the other hand, are pretty complicated regarding this matter. Since today’s engine bays are pretty crammed, access to the backside of the headlight can be a nightmare. Even to the point of having to drive the car to a garage or mechanic. For instance, this is the case with the Fiat Stilo I used to own.

What is also worth mentioning is that classical halogen car bulbs are giving in to LED bulb technology. Very good alternative, in my opinion. Less electricity needed, less heat, better beam and longer life-span (in most cases).

Most new cars are rolling out with LED technology as a standard, for both front and back lights. The only downside is the cost of repair when they burn out. A hefty sum is charged for this.



oxygen sensor-check engine light is on

As long as the ECU has been in the car, so have the sensors. Sensors are the “eyes and ears” of the whole system and give the basic input to the ECU.

But as with all electric appliances, sensors give out to time and material fatigue. Especially if they’re installed in places that are susceptible to heat, moist, oil, filth or else.

Replacement in most cars is pretty simple and basically means taking of a couple of screws or nuts, disconnecting, taking out the old one, putting in the new one and re-connecting. This, of course, depends on the accessibility of the sensor.

Main problem here, in most cases, is making a quality diagnosis. Of course there is the OBD diagnostic tool, but a faulty sensor can be hard to pin-point and can easily lead to bigger, unneeded expenses.

Even worse, they can, sometimes, start and stop working in irregular patterns, giving false code readings.

One of the trickier car electric problems where looking twice and double-checking is worth gold.

Sensors are also one of the  main causes of the dreaded check engine problem.

If you want to learn more about the check engine problem, click here for a separate article on that topic or watch a video on our You Tube channel.





Short circuits are one of the oldest car electrical problems there is. It’s been there since the first electric installation was put on the car.

If you want to know the proper definition of a short-circuit, click here for a great explanation on Wikipedia.

Shorts circuits can come from various reasons like damaged insulation on wires, faulty connectors, damaged appliances, faulty car bulbs, damaged car relays or else.

In most cases, short-circuits are very hard to locate (like with the broken or damaged wire problem).

Nevertheless, there is a procedure and involves an elimination process where you disconnect certain parts of the installation until you pin-point where the short-circuit may be.

Damaged wire insulation is a common cause of these types of car electrical problems. Since today’s car wiring installations are made pretty good (in terms of wire protection) these problems usually happen if there was some work done on the car.

This may include paint jobs, replacing the clutch set, engine overhaul or else. Here a pinched or damaged wire is pretty common.

If you’ve had additional appliances improperly installed (like different car radios, custom car horns or else), in terms of connecting or damaging the wiring a short-circuit can appear.

Severe cases of short-circuits can cause serious damage to the wiring looms and appliances.

If it happens, you should make a complete check up of that part of the wiring installation as the excessive heat can damage other wires in the loom.

Car electrical problems like these are not that expensive to repair in terms of tools and used material.

The hardest part is finding a short-circuit, especially if it involves huge dismantling (covers, trim parts, fuse boxes etc).




Spark plugs are for petrol engines, glow plugs are for diesel engines.

Spark plugs ignite the mixture inside the cylinder while glow plugs heat up the cylinder so the fuel can ignite more easily under pressure.

Both spark plugs and glow plugs are of sturdy design and can last for tens of thousands of kilometers, especially when they come from quality manufacturers.

Some symptoms of faulty spark plugs will be: misfires, check engine lights going on, engine working funny (not all cylinders are igniting) or else.

Glow plugs are also of sturdy design. They are essentially heaters.

Glow plugs are essentially heaters and as all heaters, will eventually burn out. Usually, they burn out one by one, it’s very rare for them to burn out all at once.

If one glow plug burns out, it mostly goes unnoticed (if you don’t have a warning light on the dash, you won’t know) as the engine will start normally. When two or more burn out, then the problems begin.

It’s most obvious with a cold start (especially in low temperatures);you have to crank a lot more than usual in order to start the car.

Best solution for these car electric problems: change the spark plugs or glow plugs on time and within the regular maintenance interval.

Besides that, always change, if possible, the complete set, not partially.




Car starter is the part of the car that’s in charge of cranking.

If you get car electrical problems of this sort, you won’t be able to start the car which means you have to solve these problems the moment you notice them.

I won’t go in to detail about the function and parts of the car starter, rather click here for a great explanation on Wikipedia.

Also before checking the car starter, make sure that the car battery and ignition switch is in good condition and functioning properly.

Some of the symptoms of a faulty car starter will be:

  1. Clicking sound (when you turn the ignition key to crank).

If you turn the key and you hear a “click” sound and the lights on the dashboard have a normal glow, ,then you should check these:

  • starter brushes (if they are depleted)
  • starter rotor
  • commutator on the rotor
  • solenoid (located on the starter)
  • shift fork (this fault is really rare)
  • weak or corroded ground connection
  • weak or corroded connection to the car starter (main power cable or the connection from the ignition switch)


  1. Bzzzzzzzz” sound appears when you turn the ignition key (but no cranking actually happens).

One part of the car starter is the drive gear. Its main function is to engage the flywheel and crank the engine.

Overtime it wears out and starts to slip. So once it engages the flywheel, instead of cranking and producing the well-known cranking sound, it slips and you hear the “bzzzzzzzzzzzz” sound.

The solution is taking off the car starter and replacing the drive gear.

    3.Weak cranking

Weak cranking means the car starter is not achieving the proper turnover speed.

In the beginning of these car electrical problems, the car may start but the problem eventually gets worse. In the end, the starter will fail completely.

Here, before repairing the car starter,  you have to make sure that the car battery condition is OK as this can cause similar symptoms to a faulty car starter.

Most common causes for this (if the car battery is OK) will be:

  • depleted starter brushes
  • rotor or stator are faulty (rarely happens, mostly caused by overheating the starter like with extensive cranking)
  • damaged rotor commutator
  • worn out bearings (front or rear)
  • starter solenoid
  • weak or corroded ground connection
  • weak or corroded connection to the car starter (main power cable or the connection from the ignition switch)


   4.No cranking at all but when you turn the ignition key the dash lights go a bit dim.

When you turn the ignition key to crank and nothing happens except the dash lights go a bit dim (they don’t cut out completely) then you should check:

  • starter brushes (if they are depleted)
  • commutator on the rotor
  • rotor
  • weak or corroded connection to the car starter (main power cable or the connection from the ignition switch)

Most of these problems can be avoided if you respect the maintenance interval.

Car starters have a service interval of their own and many people don’t pay attention to this. They are meant to be taken off, dismantled, cleaned and all necessary parts replaced. Respect this and you won’t have much problems with car starter.

Take care, also, not to over-use the car starter as it heats up very fast when extensively used (heavy cranking). If the car won’t start, rather leave it than fry the starter.

A DIY fix is an option here, although I wouldn’t recommend it without previous experience and some serious knowledge on this topic.



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Alternator is a generator that is in charge of providing electric power to your car. At the same time it recharges the car battery while driving.

If you have the time, click here for a great explanation from Wikipedia on how the alternator actually works

Car electric problems regarding the alternator mean that you can run out of electric power which means you won’t be able to drive. Also, no recharging of the car battery means no cranking or power supply when the car is in standstill.

It’s a car part that has to function properly 100% all of the time.

In order to find out if you have an alternator problem, the first thing to do is to check the alternator voltage output. Proper output is from 13.5 volts minimum to 14.5 volts max.

If you want to see how to do this, click here for a separate article on that topic or watch a video tutorial on our You Tube channel.

First sign of these car electrical problems, in most cases, will be the dash warning light coming up (the car battery icon).

As with the car starter, we’ll list some of the common problems and possible solutions for an alternator problem:

  1. Low voltage output (car battery warning light is on all the time or has a dim appearance)

This means that the alternator voltage output is too low. Low voltage is considered anything lower than 13.5 volts.

Source of problems can be:

  • Voltage regulator
  • Rectifier (the part with diodes)
  • Weak or corroded connection to the alternator (wiring that goes to the alternator)
  • Loose serpentine belt
  • Commutator-part of the rotor
  • Rotor (rarely happens)
  • Stator (rarely happens)

Weak power output is usually manifested by poor cranking, dim headlights and eventually not being able to start the car because the battery is totally depleted.


  1. High voltage output (warning light is on all the time or there is no warning light at all when turning on the ignition)

High voltage output is anything over 14.5 volts.

Source of problems can be:

  • Voltage regulator (the most common cause)
  • Stator (happens if the regulator malfunctions, causing a stator overload)
  • Rectifier (this is a rare cause but worth the check)

Tell-tale signs of these car electrical problems will be car bulbs (namely the headlight light bulbs) that frequently burn out as well as a sulfur-like smell from the engine bay.

The bad smell comes from the car battery as it’s getting to much charge and starting to boil inside.

The problem should be tended to as soon as possible as it can cause major damage to the car battery, appliances, ECU and the alternator itself.

  1. Bad alternator sound

The alternator is driven by the force of the engine. This means high revs all the time so in order to make it function properly bearings had to be installed. Also a pulley and serpentine belt is there in order to make a connection between the alternator and engine pulley.

This introduction outlines the main causes for a bad alternator sound.

By bad I mean a squeaking or a grinding sound coming from the engine bay. These are the two most common sounds.

Squeaking or screeching sound-may be caused by:
  • Worn out serpentine belt
  • Faulty belt tensioner (pulley)
  • Worn out bearings
  • Worn out or stuck alternator pulley (this is for pulleys that have a clutch-like mechanism inside for slipping when cranking the car). For the regular, stationery types, the cause may be simple material fatigue.

This type of sound is mostly produced from the serpentine belt. So it’s either slipping or rolling over a stuck rotor or pulley.

Grinding sounds may be produced by:
  • Worn out bearings
  • Faulty alternator pulley (this is for pulleys that have a clutch-like mechanism inside for slipping when starting the car).

In most cases, the bearings are the main cause of this type of bad alternator sound. Material fatigue and over tension of the serpentine belt are among the main causes of this mishap.

Just like with the car starter, the alternator has a maintenance interval of its own. Respect that, and you shouldn’t have any problems.

An alternator DIY repair is possible but previous experience is necessary to make a quality repair.




Mentioning common car electric problems wouldn’t be complete without mentioning problems with the key fob battery

This is a very easy problem to solve although it causes huge headaches if neglected.

A lot of people get themselves in to trouble especially if they don’t have a spare key at hand. You can easily end up locked out of your own car or not being able to start it.

The replacement procedure is simple for almost all key fobs and definitely a DIY job.

If you want to learn how to change a key fob battery quick and simple, click here for an article on that topic or watch a video tutorial on our You Tube channel.




Car horns can also cause car electrical problems although not that often. A car horn problem is both dangerous and annoying. Dangerous in terms of not being able to send a warning signal on time, annoying as without a car horn, it’s like you turned “mute” on the TV.

The position of the car horn (although pretty protected in most cars) makes it susceptible to moist, filth, dirt or else. Extensive, abnormal use and material fatigue (in older cars) is also a common reason for these types of car electrical problems.

How to fix a car horn problem, replace or adjust a car horn, find out what the actual problem is and more, find out by clicking here for a separate, detailed article on that topic.

You can also watch a video tutorial on our You Tube channel.


ECU (Engine Control Unit)


At the end of this list is one of the rarest car electrical problems. Namely problems with the ECU or engine control unit.

This is the brain of the whole network and is essentially the computer running your car.

The ECU unit is usually of sturdy and quality design (they have to be in order to survive the harsh environment of the car).

Problems are rarely caused by the unit itself, rather by external causes.

Most problems usually come from:

  • power overloads (like high voltage output from the alternator)
  • reversing car battery poles when changing or reconnecting the battery
  • severe short circuits
  • bad or corroded connections (like if moist gets in to the pin connector of the ECU)
  • bad ground connection.

If the ECU unit is faulty, a complete replacement should be done. I’ve seen experts fix these (they are, in fact primitive computers so why not?) but I don’t know the long-term outcome of these repairs.

This job is best left to professionals as it involves serious car knowledge and handling of computer diagnostics systems.