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TR brake light flickers, stays on, flickers

Discussion in '308/328' started by lucaslawfirm, Jan 9, 2006.

  1. lucaslawfirm

    lucaslawfirm Rookie

    Oct 26, 2005
    26
    Car stops fine, checked the fluid, seems to stay on, hit a bump it clickers, goes off, comes back on when hit breaks, sometimes, very confused. Looked at rotrs/pads, looks fine. What gives?

    Jay
     
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  3. Prova85

    Prova85 Formula 3

    Nov 13, 2003
    1,952
    So. Shore MA.
    Full Name:
    Kenny K
    Try setting and releasing the parking brake. If the handle isn't proper it will cause the light to remain on and possibly as in your case, to flicker. It's one thing to check that you haven't mentioned.
     
  4. lucaslawfirm

    lucaslawfirm Rookie

    Oct 26, 2005
    26
    still no change. Because it seems to be motion related I thought low fluid, but the fluid is where it belongs (it took a couple of tablespoons worth, but tht's all) I'll check the inner sensor wires. How long do the pads last of this car, it was driven easy by p.o. and only has 19,000 miles on it.

    Jay
     
  5. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    19,900
    Texas
    Full Name:
    Steve Magnusson
    Jay -- Just to confirm -- You do mean the small round brake warning light in the top-middle of the Driver's instrument display?

    If so, I'll take a peak at the TR wiring diagram tonight to see what's involved. Since you've been in to check the fluid level you've probably already done this, but do confirm that the wires going to the level switch on the reservoir aren't fouled in the wiper mechanism or the brake pedal lever mechanism.

    PS IIRC the small round brake warning light is only controlled by the level switch on the reservoir -- it doesn't indicate anything about the pads themselves.
     
  6. Prova85

    Prova85 Formula 3

    Nov 13, 2003
    1,952
    So. Shore MA.
    Full Name:
    Kenny K
    Steve, as I indicated above an incorrectly or not properly released brake handle will cause illumination of the warning light. At least it does on my car :)
     
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  8. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    19,900
    Texas
    Full Name:
    Steve Magnusson
    #6 Steve Magnusson, Jan 10, 2006
    Last edited by a moderator: Sep 7, 2017
    Jay -- The bad news is that there is maybe a plausible explanation for your symptom, and it involves an "ECU". Per the TR wiring diagram, the brake warning light is controlled by either the level switch in the brake fluid reservoir or by a small ECU called something like a "seat belt buzzer" or "seat belt controller" -- item 13 in the jpeg (mounted behind the fuse-relay panel). But regardless of the name, it also runs the "self-test" of the brake warning light at start-up.
    The way the system works is that the "+" side of the warning light bulb is always at +12V. If the brake fluid level gets low and the level switch closes then the "-" side of the warning light bulb is connected to ground and the bulb glows. However, when the ignition key is placed in the "start" position, a +12V signal is given to the seat belt buzzer item 13 via the B (white) wire which then connects the N (black) wire going to the "-" side of the warning light bulb to ground (so the warning light comes on whenever the starter motor is cranking just as a self-test to confirm that the bulb is OK).
    Best case, you have a bad connection at item 13 that is somehow intermittent. Worse case, something inside that item 13 seat belt buzzer ECU is truly frazzled and is wrongly putting a ground signal on the N (black) wire when it shouldn't be. You might try just unplugging item 13 and see if the false warning light events stop occurring (assuming the seat belt system can work OK with that buzzer/ECU unplugged). If the connections look OK and unplugging item 13 stops the wacky indications and you always get the bad indications when item 13 is plugged in, I think that would confirm that item 13 itself is toast. Also, is the self-test working well? -- i.e., does the warning light always comes on just after initiating starter motor cranking and go out properly? Not getting the warning light "on" during some starter cranking events would also be a bad sign for item 13.
    Anyway, that's my understanding of the situation -- give a shout if you need something else and let us know how it works out.

    PS I should correct an earlier mistake -- the red warning light is rectangular. It's the symbol printed on the light that is roundish.
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  9. lucaslawfirm

    lucaslawfirm Rookie

    Oct 26, 2005
    26
    going to try unplugging it, contact spray it, replug see what happens, got in a wreck and haven't been able to do much lately, fortunatley I was in my Q-45 and not the TR when the blind crazy lady hit me. On the bright side I am now the owner of a 04 XJR whcih is damn fast for a sedan.

    Jay
     
  10. sohailrashid

    sohailrashid Karting

    Jun 18, 2005
    101
    Canada
    Full Name:
    testacalvo
    Reviving this old thread. The brake fluid warning light has been on for a while. The fluid is fine. A couple of times I was able to make it go off by pressing the little plastic dot on the fluid reservoir but now it doesnt seem to do the trick.

    I opened up the fuse box to check item 13 that Steve mentioned but it does not exist on my 87 Testarossa version.

    Any other items I can check?
     

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