MOT regs abs warning lights

Don`t know about the law, however abs will always fail safe, there is no danger in having the abs not working.

Well it should fail on that as well it depends on how visible the light is when off. If you were to remove the light completely then it should pass but if they notice a bulb out for it then it should fail.

One word, "bendix" I'm sure Dojj will verify that too ;)

The MOT tester normally looks at a list of cars and how the ABS should light up, some stay on for 5 secs when you start car, some when you turn on ignition, some stay on longer/shorter.

Just take the bulb out and hope for the best, although you should not have bought it with the ABS light lit all the time.

It will be a faulty sensor I would imagine.

If the car is old enough, I doubt the tester will even know it has ABS

its a 1995 Cav sri 16v eco tec thingy quite nice too

failed the mot on emissions(no cat no silencers) and the abs is the other biggy rest is easy sorts beam alignment and a cv boot

in regards to the abs does removing the bulb from the dash(retro cool 80's digi dash) and taping over the abs logo constitute removing it?

got a couple of sensors to swops over and try see how it goes else its being removed

is it ok to retro remove abs from a car????

Just remove the bulb, you'd be /very/ unlucky to get caught out by a garage monkey failing you on the lamp not lighting up for pre-test.

A thought tho, does it have SRS... ? If so, just wire the ABS bulb up to the SRS light, so that both lamps come on for the airbag pre-test :)

As found in older fords? It is beacuse the servo action is via a pump. On the vaux (bosch) the brakes are sperate from the abs function. Any failure and normal braking occurs.

Older fords, renaults and some pugs i think. Its just your statement "there is no danger in having the abs not working." can be a little misleading :)

and older teeves systems....

Yeah it's fine. A few of the Ka Klub Muppets did it, but they were Muppets before they removed ABS, heh...

There's also some cars where they use the ABS to define brake balance front to rear. The reason to have a front/rear brake balancer gadget is because without one, when you brake hard, the rear tyres lose grip compared to the front tyres due to weight transfer and the car will swap ends and slide backwards into the future.

So there's a valve that makes the back brakes work much less hard than the front to avoid this happening, properly set up the front tyres will lock up before the rear tyres do and the car may end up skidding, but it will do it in the forwards direction.

With ABS, though, the wheels shouldn't ever lock up so you might as well not bother with a front/rear balancer and just use the ABS to prevent rear lockup. For a start, you don't want the rear tyres to be taking it easy when they could be braking fully to their limit, which on a non ABS with a balancer should never be the case.

Anyway, when the ABS system works in this fashion, if it fails, there is no front-rear bias system and whenever you brake hard, the back end will step out and cross the other carriageway, leaving you pointing in the wrong direction.

Not all cars with ABS do it that way, though, I would generally find out somewhere safe before assuming it is either safe or dangerous with the failed ABS.

The vaux in question uses a bias valve. I dout any manufactur will not produce a car without a bias valve as fail safe is very important with anything to do with brakes. It might not be set up as conservately though, on abs models!

The renaults have the same bias valves, with or without abs. Its normally seized solid tho, which is nice way to fail the test.

The bias valves, when they fail, transmit almost no braking to the rears so they in effect fail safe also.

Most do, my Ford does. But it's not always so.

Well, I learned this was possible when I read the handbook on sommat, Audi A8 I think it was, where they made this point about the ABS on that car.

Not really had the chance to experiment on the Ford, on my TR7 the back drums aren't doing a lot of work as the balancer is quite pronounced. I wonder if there is any point in making it less conservative? The ABS would kick in on the front and the rears would then grip gradually more as the pressure was increased still further, which might be a good thing.

A mate of mine had a Vauxhall Calibra with a VERY odd ABS malfunction...

In the wet (at least it seemed to happen to him in the rain), if the ABS kicked in, the brakes would simply release and not re-apply. I'm serious - it'd only happen if he locked a wheel. Totally weird and I don't know the cause - but, at least in this case, the ABS definately did not fail safe.

Chris.

Yeah, a colleague had a Pug 405 Mi16 and the Bendix unit failed. He ended up taking a sharp corner very very fast and was lucky to keep it on the road.

It was going to cost quite a few hundred even for a recon unit so it was eventually sold to somebody who needed the engine for a transplant into a Mini or something..

Gareth

Heh, when I first read that, it was as though the Bendix failure caused him to find a sharp twisty corner...

...a mate of mine would say that if the car went around the corner at that speed he'd not need the brakes anyway! :)

Most cars will take corners *way* faster than people imagine. But when getting it wrong can be painful it's far more usual to slow down first and take them at a slower speed, which is difficult when you find the brakes aren't actually working as you might be approaching the corner at a speed too high for it, but perfectly ok for the straight road.

I heard a similar debate to that, the other day. Story was that a guy was driving down a steep hill with an NSL, closing into a 40 zone with side roads near the bottom, as they often are.

Anyway, coming down the hill, they cooked the brakes (this was a while back when cars mostly had rubbish brakes) and so had nothing but engine braking, which wasn't doing a lot of good and they didn't dare change down because if they couldn't get it into third at that speed, they'd be freewheeling and accelerating fast (again, four speed boxes in those days, but engines would brake quite well as they would only rev up to, say, 5,000 rpm and then would be literally out of puff and would hold the car to that speed.)

A nasty moment.

Someone living in one of the side roads behind the 40 zone sees the car coming down the hill. The brake failed car blasts his horn to warn him but he pulls out. In normal circumstances this would force the other guy to brake sharply but this isn't an option so as he doesn't tear off at huge acceleration the inevitable happens and there is a teeth-rattling bang as they play the car with no boot game.

It's an interesting story because it's the only time I have heard where the insurance companies put the blame on the guy who was run into, rather than doing the shunting, on account that a warning was given and deliberately ignored.

Anyway, when the story was told, the women* reckoned it was the driver with the overheated brakes' fault. He was - you all know what they said - "going too fast". And you can even guess that up came the classic "what if a child had run into the road?" Never mind that he'd have blasted his horn but couldn't do much else except try to dodge them, he was "too fast."

Now I can see how it might be ok to blame the driver if he'd been doing some silly stuff and overheated the brakes because of that, but the whole point was that the cars of that period cooked brakes at the drop of a hat. Similarly, a fair criticism is that he could have been in third gear and that's true too, but how many of us travel at 40 / 50 mph down steep hills in third just in case the brakes fail on the way down?

These days, of course, there'd be a camera at the bottom and I wonder if "my brakes had failed" would be a defence in court? I bet not.

(* - and I dunno whether the fact that it was two women was relevant as there's plenty of male old women in this group, but be that as it may, it was actually two women in RL.)