Traditionally, the ignition and oil pressure warning lights were red and amber respectively. If either came on while the engine was running, it was a warning that something was wrong. I imagine the idea behind using green for the indicator repeater lights and blue for the main beam light was simply to make them different and, therefore, easy to distinguish at a glance - bearing in mind that, on many cars, they were simply coloured lights with no symbols or wording to show what each one meant.
|