Auto electrical

A car that won’t start, a light that won’t come on, a fault that shows up one morning and hides the next. Electrical problems are easy to guess wrong, because a flat battery, a dead alternator and a tired starter motor all look identical from the driver’s seat. We find out which one you’ve got first, and you get a quote before any part is ordered.

Signs of an auto electrical fault

• The engine cranks slowly, or you get one click and nothing else.
• Dash lights dim or flicker as you turn the key or run the electric windows.
• A battery or charging warning light stays on while you’re driving.
• A globe, a power window or a central locking motor has stopped working.
• The car has needed a jump-start more than once in a fortnight.
• A fault that comes and goes with no pattern you can pick.

What auto electrical work involves

The first job is telling the three starting faults apart. The battery is tested for voltage and for how well it holds up under load. The charging system is checked to see whether the alternator is putting current back while the engine runs. The starter motor and its circuit are tested last, because a weak battery makes a healthy starter look faulty.

Wiring and lighting faults come down to following the circuit. Power in, earth out, and every connection in between, which is where corrosion and chafed insulation usually turn up. Intermittent faults take longer, because the fault has to be happening at the moment you measure it.

Modern cars run most of their electrics through control modules, so a stored fault code is often where the work starts. A code names the circuit it saw a problem on, and the failed part still has to be traced from there. Our diagnostics page covers how that goes.

Electrics, your service and your pink slip

Battery condition, lights and warning lamps all get looked at during a routine service, so a fault that’s starting to show often turns up before it leaves you stranded. If you’re booking a logbook service, mention anything electrical when you ring so the time is set aside for it. Lights are part of the eSafety inspection as well, and a blown globe is enough to fail a pink slip.

What to tell us when you book

Tell us what it did, and when. A slow crank, one click and silence, dash lights that fade as you turn the key, or a car that ran fine yesterday and is dead this morning are four different faults. Say whether it’s happened before, whether the car has been jump-started, and roughly how long the battery has been in it.

Questions about auto electrical work

Is it the battery or the alternator?

That’s exactly what the testing answers. A car that goes flat overnight and comes good on a charger points one way. A car that starts fine, then dies while you’re driving with the battery light on, points the other. Both get tested before anything gets replaced.

Why does my battery keep going flat?

Either it no longer holds charge, the charging system isn’t refilling it, or something is drawing current while the car sits parked. A drain like that is measured with the car shut down and the circuits isolated one at a time.

Can wiring faults be repaired, or does the whole loom get replaced?

Most faults come down to a connector, an earth point or a damaged section, and those are repaired in place. Replacing a full loom is rare, and it would be quoted and agreed before any of it started.

Do you work on hybrid and electric cars?

All makes and models. There’s a separate page on hybrid and electric vehicle servicing if that’s what you’re driving.