MOT Rules re dashboard lights.

If the ABS light stayed on then the ABS was not functioning correctly, which is why it failed. Did you actually see the light stay on? Or was it caused by someone to boost business?

Not necessarily. Whether electronic or electromechanical, it's perfectly possible for whatever drives the light to fail in the 'on' position, or could be a faulty sensor.

it shouldn't have passed last year with the ABS light illuminated, the tester is right to fail it as the light has to follow a set sequence for that particular vehicle to pass the test, if its illuminated all the time it donates a problem with the ABS system.

Many thanks,

The ABS has worked perfectly with the faulty light for several years. There's a fault in the warning light circuit.

SD

What exactly do you mean by 'the ABS has worked perfectly' ...?

Also, does (or rather did) the ABS light flash when starting the ignition?

Mathew

How do you know that for sure?

Thanks,

When driving conditions have called for the ABS, it has worked faultlessly. The problem was in the warning light system not with the ABS system. Originally the light was an intermittent fault - and then stayed on continually. The light not working in itself isn't a hazard as cars do not require ABS.

I don't wish to widen the debate, I'm just hoping for a simple factual answer as to whether a car should fail an MOT merely because the ABS light system is faulty.

SD

yes it should fail as the ABS light is deemed to be part of the ABS system.

yes it should fail as the ABS light is deemed to be part of the ABS system.

Last point first - yes it should, it's a definite fail if it isn't doing what it should.

You always get a debate on here.. it's up to you whether you want to join in ;-)

Cars without ABS do not require ABS - but that light is an indication that the ABS system is working OK. When the light is doing strange things, the system *might* do strange things.

ABS works by deciding to turn your brakes OFF when you are putting them ON.. Can you see where the potential problem?

Fair enough, however it shows a lack of appreciation/understanding for the complexities of ABS operation that you think you can tell it is working in an optimum fashion based solely on driving it.

With regards to your specific query regarding whether the illumination of the light is a failure it is:

Mathew

No, as when you start the car the ABS controller performs a diagnostic test - if this fails, ALL ABS is disabled. Therefore, aside from having no ABS, the brakes will be perfectly fine.

Hellraiser............>

Yebbut... if the faulty indicator is indicative of a faulty controller then you could be in serious trouble - if it can't even control the indicator correctly then do you really want it controlling your brakes?

Hence why an incorrectly behaving indicator is an MOT failure. Of course, it could well be down to something as simple as a chafed wire permanently earthing the bulb but that's beside the point - until you know what the cause is (chafed wire or misbehaving controller) then you have to err on the side of caution (as the MOT does).

Mathew

That was my understanding however, my Fiat Coupe Turbo, had a faulty sensor on the offside rear causing the light to stay on, when last winter before changing the sensor I hit a patch of ice the ABS worked, or at least I could feel the vibrating through the brake pedal which indicated to me it was working.

How do you know?

If you're expert enough to diagnose that much, then just go and fix it yourself.

What do you think they put the fecking light there for? A bit of extra illumination? You have a car with a damn great illuminated sign saying "The Brakes Are Stuffed!!!" and you're complaing that the MOT guy wouldn't pass it?

The ABS system only has one light to tell you that there is a fault, so if the system failed completely you would have no warning as the light is already on!

Both of which mean that the ABS system is not functioning correctly.

The fact that cars do not require ABS is irelevant, if ABS is fitted, and is faulty, it is more dangerous than a car without ABS.

There is only one system, it is the ABS system, and the light is part of it. There is no separate 'ABS light system'

Thanks, the manual provides the definitive answer - thanks for your trouble.

Clearly they were wrong in previous years to pass the car with the light not working.

SD