Tell-tale (automotive)

One type lights or blinks to indicate a failure (as of oil pressure, engine temperature control, charging current, etc.

Another type lights to alert the need for specific service after a certain amount of time or distance has elapsed (e.g., to change the oil).

[6] Colour may also communicate information about the nature of the tell-tale, for example red may signify that the vehicle cannot continue driving (e.g. oil pressure).

A pair of lights indicate insufficient (cold, blue) and excessive (hot, red) engine temperature.

Unlike other types of idiot light, an MIL does not correspond to a condition that would have been read out on a gauge.

[9] On vehicles equipped with OBD-II, the light has two stages: it illuminates steadily to indicate a minor fault such as a loose gas cap or malfunction with the vehicle's emissions controls, and it flashes when a severe condition is detected to alert the driver that continued driving may cause severe damage to the engine or catalytic converter emission control system.

Early 1980s Fords, such as the LTD Crown Victoria, without the instrument option, had only this light, which indicated low oil pressure, overheating and carburetion problems without distinguishing among them.

[10] Vehicles with anti-lock braking system (ABS) have a lamp to indicate a detected failure.

As automobiles became increasingly complex, more dashboard indicator lights have been added for the status of safety and convenience systems.