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Thread: Parking brake light is buzzing

  1. #1
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    Parking brake light is buzzing

    When I pull the hand brake, the brake warning light turns on continuously (at the top of the oil temp/pressure gauge) and the flasher relay starts buzzing with a fairly high pitch. If I also have the left or right turn signal on at the same time, the brake warning light starts blinking like itís supposed to.

    It seems to me as if the brake warning light doesnít pull enough current from the flasher relay to cause it to blink normally. What could be the cause of this?
    Ď72 T/E Targa Aubergine
    Member #3833

  2. #2
    Junior Member
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    I thought this was normal behavior for that light.

  3. #3
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    I thought some years the brake lit up solid and later years it blinked; which years it changed I do not know ;maybe someone knows?
    1. Chris-Early S Registry#205
    2. '70 911S Tangerine
    3. '68 911L Euro Ossi Blue

  4. #4
    Senior Member
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    For a 72, it should blink when the handbrake is pulled or when the indicator is on.

    The handbrake doesn't pull any current unlike the bulbs in the indicators. I would start by cleaning all connections and then try a replacement flasher relay.
    Last edited by 911GP; 09-16-2019 at 10:52 PM.

  5. #5
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    Thanks for the responses. I checked the wiring diagram and the only current pulled when the handbrake is on is through the warning light itself. I know the flasher relay is designed to blink quicker when there is less current, so you can tell whether one of the turn lights is not working. However it seems odd that it would be designed to oscillate so quickly when the handbrake is on that you hear a buzzing sound.
    Ď72 T/E Targa Aubergine
    Member #3833

  6. #6
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    Definitely doesn't sound right. Mine flashes at the same blink rate as the indicators. Was it working ok previously or has it always been like this?

  7. #7
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    I only have this car since it came out of restoration about a year ago. The brake warning light didn't work at first, so my mechanic (who did the restoration) connected it with the current behavior as the result. I think a little more work is needed... the buzzing is annoying and I'm also worried that it might cause excessive wear on the flasher relay.

    I'll check the light connections and also what type of light bulb is installed.
    Ď72 T/E Targa Aubergine
    Member #3833

  8. #8
    Senior Member
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    Here is a diagram of the system. It should blink if the parking brake contact is closed, or if the brake warning light switch on the master cylinder is the problem.
    BrakeWarning.jpg
    E Sully
    1973.5 911T

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