This is an incredibly common problem and is usually traced back to a badly wired or damaged plug that joins the electrical systems of the car and the trailer. In fact, there are two halves to this plug, one which is permanently wired into the car, and the second part which is attached to the trailer and plugs into the car. Either half can give trouble.

Over time, these plugs and their wiring can become worn and damaged and the wires loosened, at which point the lights on the trailer won’t work properly. You may even find that the plug on your trailer is wired incorrectly for the car, leading to some of the lights working and others not.

An auto electrician should be able to sort this quickly and inexpensively.

This can happen and it makes a diagnosis very difficult. What you really need to do is find an expert on this make and model. The chances are they’ve seen this very problem on more than one occasion and will be able to quickly pinpoint the cause and a fix.

Some cars can have a misfire (which could conceivably prompt a shift to limp mode) but because the problem is not something that the computer controls, no fault code will be logged. A good example are the spark plugs in some late-model Holden V8s.

In this case, a spark plug that fails can cause all sorts of running problems, but because the spark plugs are not monitored by the ECU, no fault code shows up. That’s when an experienced mechanic will make the connection and replace the spark plugs. That’s the sort of workshop you need to find.

This make and model has a reputation for leaking transmission fluid either through breather outlets or plugs that should seal but don't. And one of the first signs that a transmission has lost fluid is a refusal to select a gear. Everything an automatic transmission does is through hydraulic pressure. Lose enough fluid over time, and there's insufficient pressure to make the vehicle move.

The good news is your vehicle should still be under factory warranty, so take it to an LDV dealership to be assessed. But don’t try to top up the fluid and drive it there, as this could cause more damage if the problem is something more complex.