What the scanner sees, and what it cannot
An OBD fault code is often the first clue, not the final answer. A code can point to a sensor, circuit or communication issue, but the real work starts with live data, voltage checks and a close look at the wiring around the affected system.
That is why a fault light on its own never tells the full story. A proper diagnostic pass may involve battery testing, charging checks, earth fault tracing and a test drive to see whether the fault appears under load, at idle or after a cold start.
Battery drain cases that keep draining vehicles
Parasitic drain is one of the more stubborn faults on cars, vans and fleet vehicles. A vehicle can sit overnight, then wake up flat in the morning because one circuit is staying live when it should not.
- Interior or load bay lights that stay on after the vehicle is locked
- Accessory wiring that has been tied into the wrong feed
- Control units that stay awake because a module is not shutting down properly
- Trailer wiring faults that feed back into the main harness
Drain testing needs patience, the right metre setup and a clear reading of what the vehicle is doing while it sleeps. In coastal areas like Cape Town and Milnerton, damp connectors and tired earth points can make the picture worse.
Starter, alternator and charging work that needs proper trace testing
When a vehicle turns slowly, clicks at the key or dies once it is running, the starter and charging system both need attention. A weak battery is not always the only issue, because corroded terminals, worn brushes, damaged cables and poor earthing can all sit in the same fault chain.
- Starter circuit tests at the battery, relay and solenoid points
- Alternator output checks under load and at idle
- Voltage drop testing on positive and earth paths
- Charging system checks after repair, not only before it is stripped
On fleet units, a small charging fault can turn into missed deliveries and roadside delays. That is why the test has to follow the symptom, not just the part that looks tired.
Wiring repairs that respect the original circuit
Good wiring repair is not only about making a broken wire conduct again. It also needs correct routing, proper insulation, secure joints and enough protection against vibration, heat and moisture.
We often see faults in lighting circuits, earth points, fuse boxes, trailer plugs and accessory looms where previous repairs were twisted together and taped over. Those fixes may hold for a while, then fail when the vehicle works hard or moves across rough roads.
- Broken conductors traced back to the exact failure point
- Damaged connectors replaced or repaired where practical
- Fuse box faults checked with metre readings
- Trailer wiring and added accessories rewired so the load is carried correctly
CAN bus faults and the odd behaviour they create
Modern vehicles use shared data networks so modules can talk to each other. When a CAN bus fault appears, several systems can misbehave at once, including central locking, starting, lights or warning messages on the dash.
A network fault can be caused by a shorted wire, water in a connector, a failed module or a bad ground. The trick is to separate the system-wide problem from the one circuit that is pulling the network down.
That work calls for measured testing, not random parts swapping. A technician may look at module communication, power feeds, grounds and signal integrity before any repair is made.
Mobile call-outs and workshop jobs around the Western Cape
Some faults are easiest to handle in the workshop, while others make more sense on site. Mobile call-outs help when a fleet unit is stuck at a depot, a private vehicle will not start at home, or a trailer wiring fault needs attention where the vehicle is parked.
V-Auto works from Montague Gardens and covers Cape Town, Bellville, Milnerton, Somerset West and Paarl, with call-outs also handled in Brackenfell and Durbanville. The same diagnostic thinking applies whether the job arrives at the workshop or the vehicle is inspected on location.
- Fleet supervisors can flag repeat faults across more than one vehicle
- Private owners can book diagnosis for warning lights, drains or starting problems
- Accessory fitting can be handled with wiring checks from the start
- Mobile work is useful when a vehicle cannot easily be moved
Choose the right diagnostic focus
Repeated dead batteries need drain testing first. If a dash light stays on after repair, follow scan results, live data and supporting electrical tests.
We test starter faults, alternator output, lighting circuits and trailer wiring with a clear process based on symptoms, meter readings and confirmed results.