When the key is turned and the dashboard lights come on, the ABS light (& others) will come on for a moment, then turn off within a couple of seconds if all's ok. As suggested, perhaps the question was more about what colour the light would be. For anything which just needs checking, and is not an immediate problem, the light would be orange. If it's something more serious (low brake fluid/battery charge/oil pressure(?)) then the light would be red. ABS check is orange, certainly on my cars.
For the ABS question I get the pupils to answer "This ABS light will come on and stay on" as they show the light with the key set to position 2. When pupils have just said "The warning light will show" that has also been accepted. I've had an examiner ask a pupil where they would find a reliable guage for the tyre pressure question, to which they answered "a garage" after a moment or two. I now make sure that the pupils have the pressure guage and tread guage available so they can show them.
Can't see much in the way of draw backs in relation to teaching
With some aids you need to consider if the pupils likely to have it on the cars that they drive after passing? If not, then would it be better to switch it off so they aren't used to artificial aids? With the aid in question, I presume that it should only be activating at the same time (or later than) the ADI would go for brakes so giving the pupil all reasonable chance to control the vehicle manually? If so then the pupil isn't relying on it any more than they rely on us. Can you can tell when it has activated so that you don't think that the pupil is better than they would be without it?
In my car I have the hill start assist switched off, the auto-wipers off, and I try to get the pupils using the lights themselves rather that relying on the auto setting. When I did my check test last year I mentioned this to the examiner and he was very happy that I was teaching this way.
It could also be useful to show pupils how to switch the aids on and off so that they are aware of them and can use them when they do get cars with them, and so that they understand the pros/cons.
I had a pupil once get a DF for not saying including in the answer for the demisting question that he would turn the a/c on. He was prompted several times and didn't know (as I had taught the controls mentioned in DT1, but missed an important part of the exemplar answer).
"Set all relevant controls including fan, temperature air direction / source and heated screen to clear windscreen and windows. Engine does not have to be started for this demonstration. "
So the DE had latitude under 'all relevant controls'. Frankly I think he was being petty (and it was out of character for him), but I can't argue he is correct. T'was a lesson learned. All students since know (or should know as they have been told) that the a/c is a highly effective condensation clearance method.
I fear I may be misleading my pupils after reading some of these posts . My understanding is the show me tell me questions along with their answers can be found on the official DSA site and the official DSA theory test DVD!, Providing the learner reads the DSA Qs and As then they should have no problem , Irrelevant as to the type of vehicle So I advise all my learners to visit the DSA site and study the questions in readiness for test day, during the weeks leading up to the test date I will spend 5 /10 minutes on every lesson dealing with show and tell.