semiatic

Adaptive cruise control (ACC) light

Adaptive cruise control holds a set speed and, using a front radar, slows down to keep a set gap to the vehicle ahead. Green: it is active (on Volkswagen the same lamp also shows plain cruise control or the speed limiter). Amber: adaptive cruise is not available right now, often because the radar is blocked by dirt, snow or ice.

GreenYellow / amber

Not defined by regulation: a maker convention

What to do

Green needs nothing, but you remain responsible for braking. Amber: control your speed yourself. Volkswagen's page says to stop where you can do so safely, switch off, restart and check the radar for dirt or ice; if the light stays on, have it checked.

Makes differ: what this light means on your car, the other colours it may use for the symbol and what the car wants you to do are set by the manufacturer, so your car's owner's manual is the authority.

Symbol
Speedometer dial with a needle
Colour
Green or Yellow / amber
Standard
None — a maker convention, described here from 2 makers: Volkswagen, Hyundai

Where makes differ

Volkswagen shows a speedometer symbol that turns amber when ACC is unavailable and flashes green if you go over a speed-limiter setting. Hyundai's Smart Cruise Control has no amber symbol: the cluster shows your car, the car ahead and the gap, greys it out when temporarily cancelled, and reports a fault with the master warning light and a 'Check driver assistance system' message.

Not defined by regulation: a maker convention

Neither US FMVSS 101 (Tables 1 and 2) nor UN Regulation No. 121 lists this light, so no rule fixes its symbol or its colour. What follows is what the makers cited below say; other makes, and other model years of the same make, may draw it differently.

FMVSS 101 Table 1 lists only the cruise control switch ('Automatic vehicle speed', no symbol given); neither table has an adaptive cruise tell-tale.

Other green maker lights

Lane assist (lane keeping) lightLane markings running away from you, dashed line in the middle · also yellow / amber · maker conventionAUTOHOLDAuto Hold lightThe words AUTO HOLD · also yellow / amber · maker conventionHill descent control lightCar pointing down a slope · also yellow / amber, red · maker conventionAAuto stop-start lightLetter A inside a circular arrow · also yellow / amber · maker convention

All green dashboard lights, regulated ones included

Other yellow / amber maker lights

Diesel particulate filter (DPF) lightBox full of dots with a pipe at each end · maker conventionAdBlue (DEF) warning lightLiquid container with a wavy fill line and a drop · also red · maker conventionEPCEPC (electronic power control) lightThe letters EPC · maker conventionLane assist (lane keeping) lightLane markings running away from you, dashed line in the middle · also green · maker conventionForward collision warning lightCar seen from behind with radar arcs around it · also red · maker conventionBlind spot monitor lightTwo cars side by side with signal waves between them · maker conventionAUTOHOLDAuto Hold lightThe words AUTO HOLD · also green · maker conventionPower steering warning light (EPS)Steering wheel, sometimes with an exclamation mark · also red · maker conventionWater in fuel light (diesel)Fuel pump with water drops beside it · maker conventionGearbox (transmission) warning lightCog wheel with an exclamation mark · maker convention?Key not detected lightKey with a question mark · maker conventionBulb failure (exterior light) warningLight bulb with rays and an exclamation mark · maker conventionHill descent control lightCar pointing down a slope · also green, red · maker conventionAAuto stop-start lightLetter A inside a circular arrow · also green · maker convention

All yellow / amber dashboard lights, regulated ones included

Sources

No regulation defines this light, so it is described from 2 carmakers' own manuals or owner pages, each fetched and checked on the date shown:

Written in our own words; the makers' pages cover their own models only.