The first sign you will usually get of an electrical failure happening is a warning light coming on in your car’s instrument panel. This can be a simple alternator light, as in older cars, or an LCD panel giving off a fault code. If the fault is bad enough, you will also notice dimming headlights or the instrument panel lights flickering.

If your car is in decent shape in the fist place and is being properly maintained, your battery’s reserve capacity should give you enough power to at least bring the vehicle to the side of the road safely, or even take you to the nearest gas or service station. When this happens, and you can tell that only the charging systems has failed, shut off all unnecessary electrical loads, such as the aircon, radio, chargers, etc. If there is a noise coming from your engine compartment, you will have to stop the car to check if a loose belt or component is rubbing or hitting another engine part. Coinciding with the warning lights on the dash will be a dimming of your headlights, in case you are driving at night.

In case you notice that only the headlights are dimming and there are no warning lights or indicator codes turning on in the instrument panel, this means that the charging system is the likely culprit. The alternator which keeps the battery charged during driving has a set of carbon brushes in it that wear out over time. When your car’s headlights dim, it has come to the point where the carbon brushes are worn and need to be replaced. It can also be the alternator’s regulator that has gone on the blink that is causing a charging system failure. Again, reduce the electrical load and take your car in for service as soon as possible.

Sometimes, corrosion builds up in the electrical contacts, not just in the batteries, but where the negative cable connects to the car body, or the positive cable connecting to the car’s starter. These little things can actually cause intermittent failures that are random and very difficult to trace, especially with newer cars whose electronic components rely on small changes in system voltage to work.

With today’s cars employing more sophisticated electronics, a lot of things can go wrong when individual control modules fail. Since modern cars run off a common data bus, errant voltages can feed wrong signals to the wrong modules, resulting in failure that can be difficult to trace without the aid of a diagnostic module. In situations like these, it is best to drive on to a safe place, if possible, and ask for help. Fortunately, intermittent faults like these rarely produce sudden failures that leave you stranded in the middle of nowhere. If your car throws a fault code, or your alternator light blinks on, don’t delay service on your electrical system.