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Strange "Brake Pad" warning light.

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by A1an, Nov 23, 2011.

  1. A1an
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    A1an New Member

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    My "Pad Low" light has been coming on recently although the pads and wires are fine. I had a sneaky feeling it might be the battery that was at fault, the warning light would ping on when I turned the lights on or started the car. The fault was getting progressively worse.

    Today I replaced the battery with a Bosch Silver HD, unfortunately it didnt cure it, I took the earth cable off whilst I had the battery out and gave the contacts a good clean as I thought the contact between body and cable would be dodgy after the scuttle filling with water due to those stupid drain holes.

    Any thoughts where to look next?
    Last edited: Nov 23, 2011
    #1
  2. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    I have the very same issue, sometimes (damper days?) the light comes on for no reason, other times it comes on as soon as I turn on dipped beam. It did it so reliably that I bought a new light switch (£84!) I knew the switch was dodgy as I had the fog lights coming on at random times. The switch cured that, but made no difference to the pad light.

    I've had HIDs for years with no error codes so doubt it is those, the only thing I've done different is fit the plastic cover over the aircon pipes, not sure if that has affected the ballast in some way. I don't think so though as the light comes on the instant the lights are turned on. I've fiddled about with stuff and have I think eliminated any link between headlights and pad light....

    A few of the individual LEDs on my 9 LED sidelights were gone causing an occasional bulb out warning on the N/S when starting. New 15 LED sidelights cured the light out warning, but nothing else.

    Brake fluid level is fine and the sensor 'looks' ok....

    I've done a visual check of the sensor connections and nothing is obviously wrong. I think my next step is to bridge the two connections at the plug - I'm told that joining them to complete the circuit will cause the light to go out. Fingers crossed, will be a few day till I can do that.
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  3. white.akita
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    white.akita Member

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    yep twisting the wires together gets the light to go out, it one of the first things i did to my a4 when i bought it.
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  4. bowen
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    bowen Member

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    i get this, as soon as i start the car; 3 beeps with brakes and the (!) sign
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  5. marktdisport
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    marktdisport Active Member

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    i also modified my plug
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  6. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    Is that red warning? If so then I think it's low battery power at start up causing a low ABS pressure warning.

    The low pad light I'm (we're?) suffering from is orange and accompanied by the same beep as when the low fuel light comes on.
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  7. bowen
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    bowen Member

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    oh, i didnt know that. learn something new every day. What is the purpose of the red (!) warning?

    So a new battery i assume would fix this?
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  8. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    Does it tend to do it on a cold start on colder days? When I had it I had the battery tested and it wad reportedly fine, but I bought a new battery for another issue and it fixed this too. I think it's the first sign that the battery is weakening.
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  9. A1an
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    A1an New Member

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    I still reckon the problem is power related purely from thinking logically, when the ignition is turned on "OK" comes up on the dash, as soon as you turned the key and draw power it beeps and the warning comes on.

    I never had a problem with the warning coming on with my halogen lights but as soon as I changed to HID's the warning came up as I switched them on. HID lights takes more "starting" than a filament bulb.

    On my way back from Inverness last weekend I noticed the warning came on when I went over a particular section of uneven road, it came on EXACTLY the same place the weekend past.

    Its not a big issue but its bloody annoying, I like things to work as they should.
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  10. jbcalvin
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    jbcalvin Member

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    I think I have something similar going on, I fitted HID's earlier this year (copied Woorlord's guide so they are all fitted inside the units factory style) and occasionally I would get the red BRAKE ! warning on the DIS along with the handbrake, ABS/ESP and yellow pad warning lights coming on, I thought it was just a bit of interference with the HID's (even though they are meant to be error free) and was planning on moving the front crash sensor wiring next time I have the bumper off to try and resolve it, however it is starting to do it more frequently, even when the lights are not on.

    I put a brand new Bosch Silver HD battery in the car in February and recently had the alternator tensioner changed, so that was all checked at the same time........

    If anyone has any suggestions it would be helpful.....
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  11. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    Mine comes on too often without the headlights being on for it to be purely HID related. I also can't help thinking I've had the same set of HID's for four years or so and they've never triggered a warning, so it would be odd for them to start doing so now.
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  12. jbcalvin
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    jbcalvin Member

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    Quattrojames, did replacing the headlight switch make any difference, mine is pretty old and dims at night when the lights are on so I was planning on changing it soon....

    Considering the number of people who have this problem, I would imagine someone has a cure for it....
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  13. Mike B
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    Mike B Member

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    It helps if you move the battery cable away from the sensor under the fluid res and put some foam between them to insulate against the spike wchich seems to trigger the warning on starting.This and charging the battery worked 90% on my last A4 and a new battery did the trick on my present car 100%
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  14. marktdisport
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    marktdisport Active Member

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    off topic a little but around 6yrs ago i owned a gt tdi130 golf which kept spitting its dummy out and going into limp mode and doing strange electrical things and after lots of testing it was the starter motor at fault drawing loads n loads of amps think it went down to 8 and half volts cranking which made lots of other issues at the time..... maybe worth a check rather than blaming a dud battery all the time !!! sorry if its off topic
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  15. swarcup
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    swarcup Active Member

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    i dont have hids and have had the pad warning light come on twice over the last month, pads are only 4 months old. both times it has been wet. i have putr it down to moisture bridging the contact momentarily and the warning light only resets when the engine is stopped. shouldnt happen but annoying
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  16. jbcalvin
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    jbcalvin Member

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    Swarcup, is it just the yellow pad warning light or the main red one I was talking about in my post.......... I drive in the wet a lot (downside of living in western Scotland) so if it is this, I will get these checked at the weekend.....
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  17. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    It made no difference to the orange low pad light, but it cured the random fog light illumination issue.
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  18. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    Are you talking purely about the red brake light warning here Mike?
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  19. bowen
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    bowen Member

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    Mine (!) warning light on the DIS comes on every morning recently (wet weather?), brakes are fairly new. I may try a new battery.
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  20. dope
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    dope alcoholic pervert

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    I got exactly this for the first time the other day. My pads are fine, so I assumed it was brake fluid level, which was a little low I guess but nothing to freak out about.
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  21. Mike B
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    Mike B Member

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    Yes its the sensor underneath the res that the battery cable touches or in my case presses against and triggers the brake light and three bells .I assume the current creates some sort of contact and sets off the sensor.You can loosen the cable from its fixings and create a gap which I filled with foam pipe lagging which helped a lot.My present car has a new battery too and timing is spot on so it starts with so much cranking
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  22. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    OK, unfortunately it's the orange low pad light we're suffering from.
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  23. Mike B
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    Mike B Member

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    Yes James but some still get the red light too
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  24. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    There's umpteen threads on that already though, and the issue seems to be getting confused.
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  25. A1an
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    A1an New Member

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    Had a good run in the car tonight, HID's on, rear screen demister on and heated seats on full blast.

    No sign of the Pad Low warning though.
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  26. bowen
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    bowen Member

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    Ah I think I may be getting confused. My warning light is a red (!) BRAKES light that comes on most mornings. Then this morning my climate control panel is completely dead, could this be related? Failing battery?

    Cheers
    #26

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