I am just about old enough to remember all the fuss that people made when electronic ignition and fuel injection started to find their way into ordinary family cars in the late 1980s. “When it goes wrong you’ll have to throw the car away. You’ll never be able to repair it.” As it turned out, the newfangled systems were far more reliable than carburettors and contact breaker ignition, never needed adjusting and normally lasted the life of the car. But when they did go wrong, those early systems posed some challenges for mechanics working outside the main dealership networks.
Most of the new systems had some kind of fault diagnosis function built in, but each manufacturer had its own protocol, and for a while there was little you could do to diagnose a system fault, other than keep swapping components until the fault went away, or take your car to a franchised dealer and pay whatever price they demanded to plug your car into their computer. Eventually consumer pressure led to a standardised system known as OBDII: any car built from the late 1990s onwards should have a diagnostic port of standardised design which can be interrogated with a £20 handheld code reader.
On-board diagnostics started to appear on Land Rovers in the early 1990s, as electronic engineering solutions gradually took over from old-fashioned mechanical ones. I think the Discovery 300Tdi automatic, with its fly-by-wire throttle control, may have been the first Solihull product to have an on-board diagnostic facility but I might be wrong about that. The Lucas fuel injection system used on Range Rovers from the mid 1980s was a primitive beast with not too many sensors and widgets, but fault diagnosis on those systems is done with a multi-meter and can be tricky unless you have a good understanding of how
