Assume that you left the headlights on by turning on the headlights with MANUAL
ID: 2083557 • Letter: A
Question
Assume that you left the headlights on by turning on the headlights with MANUAL SWITCH. Assume that it was raining outside. You parked your car and walked away without turning the headlights off. You noticed that the headlights were on when you reached the front door of your home. Now, you would like to turn the headlights off by operating the remote (key) switch without walking back to your car in the heavy rain. Realize that you had already turned ON the manual switch for the headlights [NO (normally open) switch] in your car. Do you see any Plausible PLC idea?? Provide your own ladder logic diagram with your answer.Explanation / Answer
Headlights in cars might sound like a simple subject. If they’re on, they’re on, and it’s easy to tell because you can see where you’re going. Right?
Well, that isn’t always the case. Nowadays, with the rise of automatic headlights and daytime running lights, (DRLs) it isn’t always quite so easy to fathom which lights your car is showing.
It doesn’t help that many cars nowadays have dashboard lights that come on any time the engine’s running – rather than only with the headlights, as they used to – meaning another visual cue that many drivers once used can no longer be relied upon.
So which lights should you have on, and how can you tell whether they are? And what do those headlight symbols actually mean? Here’s our guide to make sure you’re no longer in the dark.
In the top one, the headlights are turned off, meaning the car’s DRLs are active. In the lower image, the car's dipped-beam headlights are turned on.
Note that in both images, the dashboard lights are lit. Like many modern cars, this one features dashboard lights that come on when you turn on the ignition.
As a result, the dashboard lights are no longer a sure-fire way of working out out whether the headlights are turned on. In fact, the only way to tell in the above images is the slightly brighter beam from the headlights
Some cars feature a sidelight warning light, to show you when your sidelights are turned on, while others feature warning lights for both sidelights and headlights. But not all do, which means the only way to reliably tell whether your lights are turned on or not is to check the position of the switch.
Now that full-time dashboard lights are becoming commonplace, more manufacturers should be including dipped-beam telltales – but sadly, few do so, which is leaving many drivers baffled.
If you haven’t got a dipped-beam telltale – and, as we’ve just explained, you probably haven’t then the only sure-fire way to check which headlights you have turned on is to check the switch itself.
The vast majority of headlight switches in modern cars are mounted either on the dashboard, to the right-hand side of the steering wheel, or on the end of the indicator stalk.
Every headlight switch will include positions for sidelights and headlights, and there’ll also be a button or switch to turn on your rear fog lights, which is usually located nearby.
Some headlight switches also feature an extra position, marked ‘Auto’ or featuring a headlamp symbol overlaid with the letter ‘A’. If your car is fitted with automatic headlamps, this is how to activate them – more on which later.
Some cars will also be fitted with front fog lamps which, if fitted, will usually have a switch next to or near that of the rear fog lights.
All cars will also have full-beam headlights, which must only be used if there is no other traffic on the road ahead of you, and are activated using the indicator stalk. Some cars may have an automatic full-beam function, which detects when the road is clear and turns the full beams on and off for you.
Here’s a rough guide to your headlamp switch. Not all headlamp switches will be laid out this way, but the symbols will mostly look the same.