Why Is The Brake Warning Light Still On?

[davewill]

My mechanic mate changed the front pads on my 2002 TDI on saturday

Everything is fine, brakes work great

However the brake warning light has stayed on

Does this have to be reset at a fraud dealer?

The warning light came on a few weeks ago, and i have been driving with it on until the new pads were fitted

Any thoughts please

Thanks :(

[Masked Marauder]

Were the pad wear indicators built into the pads or separate?

 

If separate then they work by a wire loop in the pad turning the light OUT if the loop is un-broken and the circuit is complete.

 

When the pads wear away the loop contacts the edge of the disk and wears through, the circut is boroken and the light stays on.

[davewill]

The old (and new brake pads) had a cable going from them to a connector block

My mate unplugged the old one and then plugged the new ones back in after he had fitted them, but the warning light stayed on

Does that help?

Thanks

[davewill]

Sorry to go on, but does anyone have an answer?

Thanks :unsure:

[Ivor_E_Tower]

Does the Galaxy have dual circuit brakes (does any car nowadays with ABS)? When I was younger I remember dual circuit brakes being plugged as a real safety advantage; is it now law to have them?

Reason I ask is because if the fluid has been moved around when the pads were changed, it may have disturbed a sensor that monitors the level between the 2 circuits and caused it to trip. This will require a re-set. I can remember having to sort this for my parents' car back in the 1970's when the local garage changed the brake fluid and activated the brake circuit failure light. They spent an hour trying to sort it and we collected the car with the red lamp glowing and a sorry excuse that they couldn't turn it off. Got it home and 10 minutes later I had it fixed. Mind you, that was in the days when you had room to climb into the engine bay alongside the engine. Modern transverse stuff all squeezed in tight, I don't know....

[Dave-G]

;) This isn't a statement, it's a question:do the rear pads have sensors? :angry:

[davewill]

The rear brake pads do have sensors, but i know that they are only 50% worn, so i don't think that it is a rear brake pad warning

[Topbloke]

i will try to answer your question if the front brakes were worn low enough to trip the light then i would suspect that the new sensor loops (tiss what they are called) are faulty the way to test them will be dissconnect the new loops and with a small piece of wire stripped both ends connect into connectors both sides on the vehicle and the light should go out then pull one wire out and reconnect the pad wire if light comes back on then that loop is faulty if not then connect other loop and if light comes on that is the faulty loop, if you are not that fussed you can leave the wire in permanently this will not affect the performance or safety of the vehicle but it will not give a warning when the pads are low ie 20k miles from now .

all the above is only to be used if the brke fluid level is correct it may be low after the pads have been changed depending on how he changed the pads!!!!!

hope this helps ;) :angry:

[davewill]

Topbloke

 

Thanks for your help, i will try this out at the weekend

 

Regards

 

Davewill :)

[Topbloke]

davewill if you need further help with this pm me and i will help best as i can

[Denis]

Logically, I think that once the pads have worn down to the wire, the warning light should remain on- ie logged in the computer until reset. This is for safety reasons- I could imagine some people might just ignore a warning lamp that only came on when they braked- as would be the case if the circuit was simple bulb, one end connected to +12 and the other end earthed through the pad sensor wire.

 

So my guess is that a visit to a dealer will be necessary to reset the computer.

[Ivor_E_Tower]

What happens on the Galaxy though? If the pads wear to the warning limit, does the light only come on when you brake, or once lit, does it stay on until reset, irrespective of whether or not you are braking?

[davewill]

Ivor

 

In my case the warning light came on, and stayed on. So everytime i started the car the light came on and a warning sound was made (similar to low fuel warning)

It certainly makes you think about changing the pads as soon as possible. Only problem now is that bloody light and buzzer are still going off!

[Ivor_E_Tower]

Grrrr - that means that you must need a computer to be plugged in to silence the wretched thing

:lol:

Can't make one out of wood

:lol:

[ALARM MAN]

But Ivor have you tried

[Ivor_E_Tower]

Yes - I called it "abacus"

:ph34r:

[Guest Andy]

if the loops broken then the light/warning doo daa will bing like a microwave until rectafied,nothing needs resetting,dodgy warning wires are a commen problem even in new pads,thankfully 90% of cars like mercedes and bmw have seperate warning indicater wires,unless you have a porpers galaxy like mine with no indicaters whatsoever.

:) :) :) :)

[Masked Marauder]

What happens on the Galaxy though? If the pads wear to the warning limit, does the light only come on when you brake, or once lit, does it stay on until reset, irrespective of whether or not you are braking?

In the olden days, when you were a lad, they worked by a contact on the pad earthing out against the disc. Trouble was if the wire broke or was cut they did not work, or if ignored long enough they stopped working as the wire was worn away.

 

Now most cars have a closed loop with the sensor being part of the loop. When the ignition key is first turned the system checks the loop is closed and turns out the light on the dash. When the pads wear the disc cuts through the wire in the sensor breaking the loop. If the loop is broken the light stays on.

 

This means that if a heavy handed mechanic damages the wires into the loom connector when un-plugging the old pads then the light will also stay on.

 

In short there is either a break in the circut or the lamp needs re-setting somehow. Whether this needs a trip to the dealers to do or not, I can not help with!

[Topbloke]

Do we have a fix then davewill ;)

[Ivor_E_Tower]

If what Masked Marauder says is true, and it sounds correct, then hopefully when the integrity of the loop is restored, the lamp will reset itself next time that the car is started and the computers go through their diagnostic checks.

[davewill]

I've been away, so only just picked back upon this

Masked Maruder i think you've hit the nail on the head!

When i questioned my mechanic mate, it seems that the sensor wires on the original pads, had been interweaved with the brake pipes, thus making them difficult to remove. So to save time he cut them just above the pads, and then undid the connectors. :P Re fitted the new pads, and bingo the light stayed on.

I think i am resigned to taking it to the local Fraud dealer and (hopefully) getting a reset. Its due a service soon so will ask at the same time

 

Thanks for your help (got used to the ping ping and light on, now!) :P