ABS Switch on Dash?

Crossle · 20-07-16, 07:25 AM

On my B3 Coupe I have an ABS Switch on the dashboard. I have only just bought the car and bought it with a know brake problem so when I jumped in it for the first time I wasnt surprised to see a yellow ABS light lit up on the dash. I have however only just noticed a switch with ABS marked on it on the dash and when I pressed it the ABS light goes out. I am now thinking that the light on the dash is not a warning light but a light to mark that ABS is on? Then when you hit the switch your switching ABS off and so the light goes out?

All in all meaning that hopefully I dont have an ABS fault or sensor fault after all!!

leggy · 20-07-16, 07:43 AM

I have ABS switch on my B4 dash Crossle...
it turns the Anti-lock Brake System on & off; there's more about it and how it works in the instruction manual (P34/35 in mine).
If your Coupe didnt come with a manual, well I dont mind scanning the pages of mine and emailing them to you.

John. · 20-07-16, 07:53 AM

Quote:

Originally Posted by Crossle

Then when you hit the switch your switching ABS off and so the light goes out?

It's the other way round, light off-ABS operational, light on-ABS disabled. I think their logic was that in certain conditions (snow/ice) you get more control with the ABS off?.....or something like that.

Crossle · 20-07-16, 08:03 AM

Can honestly say I've never heard of that on a car before but what a great idea! I absolutely hate ABS, just causes brake problems rather than brake assistance!

Thanks for your help

leggy · 20-07-16, 08:08 AM

Quote:

Originally Posted by John.

It's the other way round, light off-ABS operational, light on-ABS disabled. I think their logic was that in certain conditions (snow/ice) you get more control with the ABS off?.....or something like that.

Yup, my ABS light is off john....
meaning the ABS system is switched on.

Manual states to switch off (so light on) for a short time if driving at low speeds, or as you say, in snow/ice conditions.

Crossle · 20-07-16, 08:33 AM

Mine is always on when you start the car, to get the light off you would physically have to switch it off every time which seems a bit strange

leggy · 20-07-16, 09:15 AM

Yeh, that does seem strange Crossle...
is your switch level with the other switches on the dash? as in the hazards for example, if yes, well that's the on position (light off) for the ABS.
Just as a side note: there is also an ABS warning light in the instrument panel, should come on when you put key in ignition and go off when engine is started.

You could try pressing the switch on the dash on and off a few times with key out of ignition and/or with engine running idle to see if it makes any difference - seem to recall something in the manual about NOT pressing it on/off whilst driving though!

If you've tried that and are still having to turn the ABS on (light off) manually every time, well it could be a dodgy connection in the switch itself somewhere, or may indeed be connected to the brake issue that you mentioned somehow, other than to see what comes up on a diagnostic, I honestly dont know what else to suggest, sorry!

Hanuman · 20-07-16, 03:44 PM

Turn the ignition on, and the light should go out/stay off. If it comes on there's likely a fault in the ABS system. where though?
If its anything like the earlier system, there is a combination relay which requires a number of things to be present or correct. any single fault results in the light coming on.
It requires a healthy power supply, a healthy power supply sense, ABS switch not pressed.

With the light off, if you start driving and the ABS light comes on, this usually points to a fault with one or more ABS sensors or drive shafts. The ABS is comparing the signal from each of the sensors, and if one of these is giving a poor signal, no signal, or something very different from the others, the ABS turns off; better to have normal brakes than haphazard ABS function.
problems frequently occur with corrosion on the drive shaft toothed ring, rather than the sensor. But its just as possible that the sensors may not be properly position following suspension work.

There are some notes on the subject going back over the years, so worth a search

4WDrifter · 20-07-16, 05:24 PM

At a time I was told that being able to turn the ABS off ( dash ABS light On to warn driver of no ABS ) allowed you to drive in snow conditions and lock the wheels and thus pile up loose snow in front of then to assist braking.

Crossle · 20-07-16, 06:17 PM

The switch always stays flush with the dash when I press it, with the ignition on the light comes on but stays on with the engine started and stays on all through running. If I hit the switch while the engine is running or while the ignition is on then the light goes out and stays out while running. Almost sounds like it's wired the wrong way as its doing the opposite of what it should be doing from what your all saying!

20-07-16, 03:44 PM	#8
Hanuman Trickster Classic Audi Club Member Join Date: May 2009 Location: Heckling from the cheap seats, Phnom Penh, KoW Posts: 7,016	Turn the ignition on, and the light should go out/stay off. If it comes on there's likely a fault in the ABS system. where though? If its anything like the earlier system, there is a combination relay which requires a number of things to be present or correct. any single fault results in the light coming on. It requires a healthy power supply, a healthy power supply sense, ABS switch not pressed. With the light off, if you start driving and the ABS light comes on, this usually points to a fault with one or more ABS sensors or drive shafts. The ABS is comparing the signal from each of the sensors, and if one of these is giving a poor signal, no signal, or something very different from the others, the ABS turns off; better to have normal brakes than haphazard ABS function. problems frequently occur with corrosion on the drive shaft toothed ring, rather than the sensor. But its just as possible that the sensors may not be properly position following suspension work. There are some notes on the subject going back over the years, so worth a search __________________ I wish they would keep the damned Chinese away now that I can go home, so that I can enjoy Fish amok and a draught Angkor

20-07-16, 07:43 AM	#2
leggy Senior Member Join Date: Nov 2014 Posts: 1,650	I have ABS switch on my B4 dash Crossle... it turns the Anti-lock Brake System on & off; there's more about it and how it works in the instruction manual (P34/35 in mine). If your Coupe didnt come with a manual, well I dont mind scanning the pages of mine and emailing them to you.

20-07-16, 08:03 AM	#4
Crossle Grown up member Classic Audi Club Member Join Date: Jul 2015 Location: northampton Posts: 266	Can honestly say I've never heard of that on a car before but what a great idea! I absolutely hate ABS, just causes brake problems rather than brake assistance! Thanks for your help

20-07-16, 08:33 AM	#6
Crossle Grown up member Classic Audi Club Member Join Date: Jul 2015 Location: northampton Posts: 266	Mine is always on when you start the car, to get the light off you would physically have to switch it off every time which seems a bit strange

20-07-16, 09:15 AM	#7
leggy Senior Member Join Date: Nov 2014 Posts: 1,650	Yeh, that does seem strange Crossle... is your switch level with the other switches on the dash? as in the hazards for example, if yes, well that's the on position (light off) for the ABS. Just as a side note: there is also an ABS warning light in the instrument panel, should come on when you put key in ignition and go off when engine is started. You could try pressing the switch on the dash on and off a few times with key out of ignition and/or with engine running idle to see if it makes any difference - seem to recall something in the manual about NOT pressing it on/off whilst driving though! If you've tried that and are still having to turn the ABS on (light off) manually every time, well it could be a dodgy connection in the switch itself somewhere, or may indeed be connected to the brake issue that you mentioned somehow, other than to see what comes up on a diagnostic, I honestly dont know what else to suggest, sorry!

20-07-16, 05:24 PM	#9
4WDrifter Grown up member Classic Audi Club Member Join Date: Jun 2013 Location: Northern Ireland Posts: 209	At a time I was told that being able to turn the ABS off ( dash ABS light On to warn driver of no ABS ) allowed you to drive in snow conditions and lock the wheels and thus pile up loose snow in front of then to assist braking.

20-07-16, 06:17 PM	#10
Crossle Grown up member Classic Audi Club Member Join Date: Jul 2015 Location: northampton Posts: 266	The switch always stays flush with the dash when I press it, with the ignition on the light comes on but stays on with the engine started and stays on all through running. If I hit the switch while the engine is running or while the ignition is on then the light goes out and stays out while running. Almost sounds like it's wired the wrong way as its doing the opposite of what it should be doing from what your all saying!