Cavalier ABS light

certainly this is the case with Honda abs, so I see no reason Vauxhall should be different, also it stops the cruise control!

mrcheerful

Take the bulb out of the ABS light. That'll fix it boy.

Ted Rubberford. The Man In The Latex Skirt.

No. That would disable the ABS, and mean it would fail the MoT, plus the brakes become dangerously unbalanced on some vehicles (granada springs to my mind very vividly)

mrcheerful

again then put the new bulb back in and see if the abs light stays out

Seems obvious but remove the possibility of coincidence at the time of the original bulb change

Tony

Would it? I'd have thought that if the ABS light's coming on it indicates a fault that's there, and removing it isn't neccessarily going to remove a vital link in the ABS circuit. Sounds like it was just a blown brake light bulb anyway.

But surely if the ABS light wasn't visibly on for the MOT, then they wouldn't fail it, would they? I mean, it's not like the brake rollers have got a mode to simulate traction becoming a bit of an issue, to actually properly test the ABS, is it?

Peter

They check it works at switch on time. If it doesn't they just assume the bulb has been removed because of a fault and fail the car anyway.

if its got ABS fitted and the ABS function light fails to display or doesn't extinguish in the correct manner then its a fail. The correct sequence is displayed on the ABS data chart that every MOT testing station must display.

The bulb serves two purposes - in normal use it comes on when there's a problem, but at first switch on it acts as a self test - it comes on then once the system has checked itself out it goes out.

If it doesn't come on at startup the MOT treats it as a total ABS failure and fails it.

So all one needs to do is insulate the bulb from the PC board, and wire it directly into the ignition switch with a delay timer. Problem solved. :-) Mike.

but you won't know if the system works will you? or at least not till after the crash you could have avoided, modifying the abs could even invalidate the insurance (if they find out) So, all in all, not a good idea.

mrcheerful

I freely admit to knowing next to bugger all about ABS systems, but would a car with non-working ABS really be any more dangerous than the same car that just didn't have ABS to start with?

Peter

Depends.

For instance, I believe some ABS systems do the front/rear load proportioning instead of a valve. This is bad if the ABS system is not functioning and you decide to brake hard on a corner and the rears lock as they are given 50/50bias instead of whatever the computer thinks is appropriate.

I think Different systems fail in different ways. If an ABS system thinks all the wheels are locked when they aren't it won't allow any braking force to be applied at all. I think some systems have more reliable ways of ensuring this doesn't happen than others.

The ABS on my BX has pulled a couple of weird moves on me when I had a chafed sensor wire making intermittent contact. After doing something funny and a fresh application of the brakes, it would usually decide something was amiss and switch the light on and stop ABSing.

Douglas

The message from "AstraVanMan" contains these words:

Potentially, yes. As I understand it, they lack a rear proportioning valve, relying on the ABS to do the job of stopping the back brakes locking. It it ain't working the back brakes will have nothing to keep them in proportion to the fronts.

not quite so simple Mike, re my earlier post all ABS systems follow a function sequence.

from the testers manual.

1. if the vehicle is fitted with an anti-lock braking system, check that the warning lamp. a. illuminates b. follows the correct sequence of operation. Note : the sequence varies with the type of system. Refer to the manufacture's or other reliable data, eg purpose produced charts, books ect.

reason for rejection. a. the warning lamp does not illuminate. b. the warning lamp does not follow the correct sequence of operation. c. the warning lamp indicates an ABS fault.

this applies to all systems fitted as standard , and to ' optional ' systems fitted.

This is a funny one.

The light is only tested to show the ABS fail detect system is working. They don't care about ABS! Just the light.

I had a friend with a fault on their system which meant the light didn't go out *but* the ABS still worked fine.

This was an MOT fail.

If the light didn't go out *and* the ABS didn't work, the lights function is just right, so the garage said they would have passed it.

If the light didn't go out but the ABS does work, the light is malfunctioning, so it's a fail.

Pete.

its not easy being an MOT tester, honest. some days you come up against things or customers were you just wanna bang yer head against the wall .

two phrases are banged into us during mot refreshers.

C.Y.A = Cover Your Arse & P.A.N.D.A = Pass And Advise.

I must go through more advise pads then VT30 failure sheets !

I haven't noticed any variation in the check sequence with the ABS on different cars. They all seem to light the ABS warning bulb briefly when the ignition is turned on, then go out. I'm sure with a delay timer that sequence could be simulated well enough to fool most MOT testers. In any case, was only joking. It would probably be more hassle than fixing the ABS properly. Mike.

On a similar car I would say the working ABS one would be better. But having recently drove my nephews 1987 VW Polo (non servo) which had just passed it's MOT, I would say a non working ABS car with pads worn down to the metal would still have better performing brakes than the Polo.

Wasn't the middle pedal purely ornamental on Polos and floGs of that vintage?