75 Brake Warning Light, The brake warning light on the combo gauge is flashing |
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75 Brake Warning Light, The brake warning light on the combo gauge is flashing |
dennisphelan |
Jan 28 2019, 12:56 PM
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#1
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Newbie Group: Members Posts: 15 Joined: 10-December 18 From: Dundee Oregon Member No.: 22,713 Region Association: Pacific Northwest |
The large red brake warning light on the combo gauge is flashing. The emergency brake is disengaged. I checked the brake master cylinder and the one wire ( it only has one connection) that goes to it is attached. It appears I have some fluid leaking as the connection was wet with fluid. The car hasn't been driven in 12 years so I am sure many things could be wrong. What is the switch on the master cylinder sensing?
Thanks, Dennis Phelan |
914_teener |
Jan 28 2019, 01:47 PM
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#2
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914 Guru Group: Members Posts: 5,193 Joined: 31-August 08 From: So. Cal Member No.: 9,489 Region Association: Southern California |
The large red brake warning light on the combo gauge is flashing. The emergency brake is disengaged. I checked the brake master cylinder and the one wire ( it only has one connection) that goes to it is attached. It appears I have some fluid leaking as the connection was wet with fluid. The car hasn't been driven in 12 years so I am sure many things could be wrong. What is the switch on the master cylinder sensing? Thanks, Dennis Phelan A failed MC. So it is probably rusted and the light is doing what it is supposed to. Edit: Or switch is rusted. You don't mention if the brakes work....have a peal and stop the car or not. Need lot's more info. Good Luck. |
Spoke |
Jan 28 2019, 02:04 PM
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#3
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Jerry Group: Members Posts: 6,964 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None |
The MC switch should have a small reset button on it. If it doesn't, disconnect the wire to the switch and see if the flashing indicator goes away. As mentioned, if it is the MC switch, you need to make sure the MC is in good working condition.
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914Sixer |
Jan 29 2019, 11:02 AM
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#4
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914 Guru Group: Members Posts: 8,844 Joined: 17-January 05 From: San Angelo Texas Member No.: 3,457 Region Association: Southwest Region |
If you need a new switch let me know.
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pvollma |
Jan 29 2019, 11:21 AM
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#5
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Member Group: Members Posts: 205 Joined: 12-May 13 From: Camp Hill, PA Member No.: 15,862 Region Association: MidAtlantic Region |
The large red brake warning light on the combo gauge is flashing. The emergency brake is disengaged. I checked the brake master cylinder and the one wire ( it only has one connection) that goes to it is attached. It appears I have some fluid leaking as the connection was wet with fluid. The car hasn't been driven in 12 years so I am sure many things could be wrong. What is the switch on the master cylinder sensing? When I first picked up my new-to-me 76, the light would continue to flash after releasing the handbrake. I found that pulling it up again and then forcefully pushing it down with the release button pressed would cancel the warning light. The PO had let the car sit for a long time while he worked on it, so I suspect something in the switch that senses the handle position was hung up or corroded. After a few weeks of using this method, it was no longer needed, but, of course, YMMV. |
lierofox |
Jan 29 2019, 05:06 PM
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#6
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Member Group: Members Posts: 256 Joined: 23-June 15 From: Paso Robles, CA Member No.: 18,880 Region Association: Southern California |
I wanna say the switch is a "low pressure light" where the brake master cylinder gets depressed too far without making enough pressure. How's the pedal feel?
When I got my '75 the warning light was always on, as part of the process of going through everything and redoing the brake system I ended up replacing the master cylinder just to be on the safe side, it also had a warning light until I reset the button. Once I replaced the MC and bled the brakes it never came back again. |
Dave_Darling |
Jan 29 2019, 06:26 PM
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#7
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914 Idiot Group: Members Posts: 14,974 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California |
The light flashes when one of the brown/white wires that goes to it gets shorted to ground. The two wires go to the brake warning switch in the master cylinder, and to the button under the handbrake handle.
If the handbrake handle doesn't press the button under it down, the wire going there will be shorted to ground. If the switch in the master cylinder detects a massive loss of pressure (e.g., bleeding the brakes) it will close until the reset button in the switch is pressed. If one of the wires to those falls off and lays on the chassis, that can cause it to be shorted to ground. That will also make the light blink. But the most common thing is that you bled the brakes and didn't press the reset button on the master cylinder switch. --DD |
dennisphelan |
Jan 30 2019, 02:27 PM
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#8
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Newbie Group: Members Posts: 15 Joined: 10-December 18 From: Dundee Oregon Member No.: 22,713 Region Association: Pacific Northwest |
The large red brake warning light on the combo gauge is flashing. The emergency brake is disengaged. I checked the brake master cylinder and the one wire ( it only has one connection) that goes to it is attached. It appears I have some fluid leaking as the connection was wet with fluid. The car hasn't been driven in 12 years so I am sure many things could be wrong. What is the switch on the master cylinder sensing? Thanks, Dennis Phelan A failed MC. So it is probably rusted and the light is doing what it is supposed to. Edit: Or switch is rusted. You don't mention if the brakes work....have a peal and stop the car or not. Need lot's more info. Good Luck. Thanks for the reply. |
9fourteen14 |
Aug 12 2019, 04:30 PM
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#9
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PORSCHE LUVA Group: Members Posts: 135 Joined: 5-July 15 From: boston Member No.: 18,920 Region Association: North East States |
If you need a new switch let me know. Mark i might need a switch... if not an entire new Master Cyclinder... but my brakes seems to work fine. ummm Niece Attached thumbnail(s) |
914Sixer |
Aug 13 2019, 10:27 AM
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#10
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914 Guru Group: Members Posts: 8,844 Joined: 17-January 05 From: San Angelo Texas Member No.: 3,457 Region Association: Southwest Region |
Here you go, used but good condition. Reset button works. $20 shipped.
Attached image(s) |
jcd914 |
Aug 14 2019, 01:50 AM
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#11
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Advanced Member Group: Members Posts: 2,081 Joined: 7-February 08 From: Sacramento, CA Member No.: 8,684 Region Association: Northern California |
Disconnect the wire from the switch on the master cylinder and see if that stops your flashing brake light. Make sure the wire doesn't ground against anything.
If not make sure your hand brake lever is all the way down and pushing the switch. If still not, unscrew the brake lever switch and pull the wire out enough to make sure it isn't grounding against anything. The brake warning light is triggered by grounding the circuit at either the master cylinder or the hand brake switch. If neither of these wires is grounded and the light still flashes there is a short to ground somewhere in one of the wires. Some cars had a third wire for a brake fluid level switch, near the brake reservoir. If your car has the extra wire it could be grounded and causing the light to flash. Jim |
914_teener |
Aug 14 2019, 09:56 AM
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#12
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914 Guru Group: Members Posts: 5,193 Joined: 31-August 08 From: So. Cal Member No.: 9,489 Region Association: Southern California |
The large red brake warning light on the combo gauge is flashing. The emergency brake is disengaged. I checked the brake master cylinder and the one wire ( it only has one connection) that goes to it is attached. It appears I have some fluid leaking as the connection was wet with fluid. The car hasn't been driven in 12 years so I am sure many things could be wrong. What is the switch on the master cylinder sensing? Thanks, Dennis Phelan A failed MC. So it is probably rusted and the light is doing what it is supposed to. Edit: Or switch is rusted. You don't mention if the brakes work....have a peal and stop the car or not. Need lot's more info. Good Luck. So ......admins.....Ii didn't post this. Very weird. |
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