Drive An Old Car? Follow These Tips For A Healthy Electrical System

It’s no secret that, the older your car is, the more likely things are to go wrong with it. It makes no difference how you maintain your car. That’s because age and wear-related parts will start to fail as time goes on.

If you drive an old car, it’s common for cars of your vintage to have some electrical “gremlins” as I call them. When your car’s electrics become faulty, all sorts of weird and downright strange problems can occur.

That’s why it is important to keep your car’s electrical system in check. By following these top tips, you can make sure the electrics in your pride and joy aren’t something you need to worry about! Here is what you need to know:


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Many car owners get surprised when they try to start their cars and find that not much happens. Apart from some weird noises coming from the starter motor! The main culprit of a lot of electrical problems in vehicles is the battery.

To crank the engine, the car needs a lot of electricity or “cranking amps.” That power gets transferred to the starter motor, which itself is connected to a flywheel in the engine. When the first cars of the 19th and 20th centuries got built, you had to crank them by hand with a lever.

All modern cars get started by means of a key in the ignition or a button for keyless push-button starting. Whenever there are any starting problems, everyone gets told to look at the battery first.

Car batteries are usually good for around five or so years. After that, you will need to have it replaced with a brand new one. If your car gets used for long journeys on a daily basis, your battery might last longer than five years.

But, for those that drive short, infrequent trips, batteries become faulty at around five years of age. You can check if your battery is defective by connecting a simple battery tester to the positive and negative posts. Those of you with a good knowledge of electronics could use a multimeter instead.

Batteries are 12-volt devices. Does the voltage across the terminals measure less than 12.3 volts when you have a friend trying to start your engine? If so, it means your battery is dead.

Once you get a new battery for your car, make sure you protect the terminals on it. You can do this by covering the top with a layer of copper grease or Vaseline to protect them from corrosion.

Starter Motor

The next stage is to check the condition of your starter motor. Does it over-run when you start your engine from cold? Is your car struggling to start more often these days? If so, these are all signs that your starter motor may need refurbishment or replacement.

Using a multimeter, you first need to check that the starter motor is receiving some electricity from the battery. If it doesn’t, the problem is to do with the wiring harness. The one that connects between the starter motor and the positive post on your battery, in case you wondered.

Usually, this signals a cut in the wiring somewhere. In some instances, it can also mean the starter motor isn’t earthed properly.

If it does receive voltage, it could mean that the start motor isn’t getting enough power from the battery. It’s worth checking that the battery is in good condition and is the right size for your car.

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The thing about alternators is that they don’t last forever. Like other car parts, alternators can fail because of age or wear-related issues. I remember the time that I was about to trade in my old car for one selling on the website last year.

I thought I had the symptoms of a dead battery, but it turned out the alternator wasn’t charging the battery as it should have done. The good news is that it was a simple test to diagnose the cause.

If you think that your alternator is faulty, here’s how to test it. First, get your multimeter out. Put the corresponding probes on the positive and negative battery terminals. Have someone start the engine and then turn the headlights on, amongst other things.

The voltage should go up from around 12.5 volts to a steady reading of around 13 to 14.5 volts. If there’s no change in voltage or the voltage drops, your alternator will need attention.

Earth leads

All modern cars use several earth leads in and around the engine bay. The main one goes from your car battery to a metal part of your vehicle’s body. Another one might come from your starter motor.

It’s important that you ensure your engine’s earth leads are in good condition. That means they shouldn’t look frayed, damaged or corroded. Should any of your leads look in poor shape, get them replaced.

You can get replacements from your friendly main dealer. Or you can just get some made up for you; car accessory stores and even eBay sellers offer such a service. If you’ve got the right tools, wiring and connectors, you could always make the leads up yourself.


Sometimes on our quest to troubleshoot an electrical problem, we forget to check the simple causes first. All modern cars use an array of fuses to protect electrical circuits. Some fuses have higher amp ratings than others.

But one thing’s for certain. If one or more of your fuses has blown, it can prevent stuff from working properly. For example, let’s say that your headlights aren’t working. You changed the bulbs, thinking they were blown, but they still don’t work.

You suspect the light switch stalk on your steering wheel might be faulty, so you change that too. Still nothing. But here’s the thing: did you check if any fuses got blown? If you did that in the first instance, you would have saved yourself a whole heap of time and money!

Now that you’ve read this blog post, you’re now armed with the skills to diagnose many common electrical problems. And you also know how to keep your electrics in tip-top condition!

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