What A Mobile Auto Electrician Actually Does

Auto electrics is the side of vehicle repair that a lot of garages are glad to see the back of. It is rarely a parts job. There is rarely a component you can point at from the driver’s seat, symptoms come and go, and one complaint — a flat battery, a warning light, a window that has stopped going up — can have half a dozen unrelated causes. What the work needs is a multimeter, the wiring diagram for that exact vehicle, a scan tool that reads live data rather than only stored codes, and the discipline to follow a circuit in order. All of that fits in a van, which is why electrical diagnosis is one of the few jobs genuinely better done where the vehicle normally sits than on a ramp twenty miles away.

Our patch runs across Derbyshire, Staffordshire and Cheshire, and the three counties present noticeably different faults. In the High Peak the dominant factors are cold, gradient and gritting salt. Along the M6 corridor through Sandbach, Stafford and Crewe it is sustained motorway work, with charging systems and smart-charge control under constant load. Across the Potteries and Derby it is dense urban stop-start driving, start-stop systems cycling endlessly, and working vans carrying accessory loads fitted by whoever was cheapest at the time. The method of diagnosis does not change from one to the other; what changes is what a sensible person looks at first.

The three families of electrical fault

Almost everything divides into three. Supply and charging faults concern whether the vehicle is getting and keeping the electricity it needs: battery condition, starter current draw, what the alternator is truly delivering at the terminals, and whether the battery management system is being told the truth about what is fitted. Network and signal faults concern the data: a sensor reporting nonsense, a CANbus line with a break or a short, a module that has dropped off the bus, or a stored code that is a symptom of something three steps upstream. Physical wiring faults are the oldest category and still the most common — chafed looms, green earth points, cracked crimps, water in a connector, and the previous repair that was twisted together and wrapped in tape.

Knowing which of the three you are in changes the order of the work completely, and getting that wrong is exactly how people end up paying for three components to cure one fault. A stored code for a wheel speed sensor is as likely to be a cable chafed through near the suspension arm as a failed sensor. A battery that keeps going flat is more often a drain or an undercharging alternator than a bad battery. The first part of a visit is therefore spent establishing which family the fault belongs to, because everything after depends on it.

Mobile diagnosis, and where it stops

Most electrical work suits a mobile visit well. Fault finding, parasitic drain tracing, charging system testing, loom and earth repairs, towbar and trailer sockets, dashcam and tracker hardwiring, lighting and accessory installs all happen at your home or your workplace — and because the vehicle stays where it normally lives, a fault that only shows itself after a car has been locked up overnight can actually be caught in the act.

There is a limit, and we are straightforward about where it sits. A job needing the dashboard out, a loom lifted from under the carpet, or several dry sheltered hours to seal a repair to a standard that lasts is work to be booked in with us rather than half-attempted on a driveway in the rain. Some complaints turn out not to be electrical at all despite presenting that way, and we would rather say so than keep testing. We carry common batteries, bulbs, relays, connectors, terminals and cable, so the ordinary faults are usually finished on the first visit instead of becoming two appointments.