Some older vehicles had a single indicator labeled "trouble" or "engine"; this was not a check engine light, but a tell-tale meant to indicate serious trouble with the engine (low oil pressure, overheating, or charging system problems) and an imminent breakdown. This usage of the "engine" light was discontinued in the mid-1980s, to prevent confusion with the check engine light. The check engine light appeared in the early 80s along with computerized engine controls. Even the earliest systems, such as
General Motors' CCC (computer command control) system had self diagnosis functionality. When the computer detected a fault, it illuminated the check engine light. Up until
OBDII, on most cars the check engine light could output codes. When two pins on the
ALDL are jumped, the light would flash the codes, for instance (blink) (pause) (blink) (blink) for code 12. Some manufacturers, such as Honda, retained this feature even after OBDII. The check engine light is commonly referred to today as the "check engine light" or the "service engine soon light". ==See also==