Brake Pressure warning switch
Thread Starter
Intermediate
Joined: Jan 2014
Posts: 36
Likes: 0
From: Jacksonville Florida
Brake Pressure warning switch
Found my brake pressure warning switch disconnected a few weeks back. Reconnected and now the brake warning light on dash stays on. Checked switch to parking brake and was ok. Disconnected switch on master cylinder and light went out. No visible leaks on switch or M/C. Possible bad switch? Found one on Amazon for @$25.00. Also what is correct voltage on switch. Just bought 01/14 and issues are starting to show up.
Melting Slicks
Joined: May 2010
Posts: 2,082
Likes: 3
From: Conowingo Maryland
Found my brake pressure warning switch disconnected a few weeks back. Reconnected and now the brake warning light on dash stays on. Checked switch to parking brake and was ok. Disconnected switch on master cylinder and light went out. No visible leaks on switch or M/C. Possible bad switch? Found one on Amazon for @$25.00. Also what is correct voltage on switch. Just bought 01/14 and issues are starting to show up.
These switches seldom go bad. My quess is loss of pressure on one side of you brakes and the switch is indicating that. You can try a switch but you are most likely go to have to fiqure out what is going on with the pressure in you brake system
Melting Slicks
Joined: Jun 2013
Posts: 3,065
Likes: 39
Okay so the purpose of the brake pressure switch is to alert when there is a difference in pressure from the front system and the rear system. There are a few possibilities.
Bad proportioning valve, bad pressure switch, clogged brake lines, bad master cylinder, electrical problems, etc.
I would say it's probably a bad switch.
This light should only come on when either the parking brake is applied, or when there is an unequal amount of pressure in the brake system, WHEN YOU STEP ON THE BRAKE PEDAL. If it's on all the time, it's more than likely a bad switch.
Sorry for this diagram being sideways. You can print it and look at it straight up.
Bad proportioning valve, bad pressure switch, clogged brake lines, bad master cylinder, electrical problems, etc.
I would say it's probably a bad switch.
This light should only come on when either the parking brake is applied, or when there is an unequal amount of pressure in the brake system, WHEN YOU STEP ON THE BRAKE PEDAL. If it's on all the time, it's more than likely a bad switch.
Sorry for this diagram being sideways. You can print it and look at it straight up.
Safety Car
Joined: Sep 2004
Posts: 3,953
Likes: 550
From: Mission Viejo CA
Like Daniel said, this switch warns you if there's an imbalance between the front and rear brake line pressures. This may happen when you bleed your brakes, so the previous owner may have had the light come on after he (or she) bled the brakes, but didn't know how to reset the light. That may be why the switch wasn't connected.
1. Leave the switch plugged in.
2. Install a tube onto a front brake caliper bleeder fitting, as you would to bleed the brakes.
3. While a helper steps on the brake pedal, open the bleeder while the helper watches the dash light. He may have to push hard on the pedal. If the light doesn't go out, close the bleeder fitting before releasing the brake pedal.
4. If the light didn't go out, repeat this procedure with a rear caliper.
1. Leave the switch plugged in.
2. Install a tube onto a front brake caliper bleeder fitting, as you would to bleed the brakes.
3. While a helper steps on the brake pedal, open the bleeder while the helper watches the dash light. He may have to push hard on the pedal. If the light doesn't go out, close the bleeder fitting before releasing the brake pedal.
4. If the light didn't go out, repeat this procedure with a rear caliper.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Sometimes the shuttle inside the master cylinder gets off center and causes the switch to close and light the BRAKE light. That usually happens when you bleed the brakes and then it gets stuck in the off-center position. My light came on after I bled the brakes recently but it went off the first time I stepped on the brake pedal.
You could try poking something sharp down into the switch opening and see if you can align the shuttle. There is a groove in it that the tip of the switch fits into. The first picture in this post shows what to look for:
http://forums.corvetteforum.com/1585621532-post1.html
You could try poking something sharp down into the switch opening and see if you can align the shuttle. There is a groove in it that the tip of the switch fits into. The first picture in this post shows what to look for:
http://forums.corvetteforum.com/1585621532-post1.html
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Verdad Gallardo
Racer
Joined: Feb 2012
Posts: 442
Likes: 3
From: Hendersonville TN
My master cylinder went bad and was replaced. The shop didn't bleed the brakes right and the light stayed on all the time. I took it back a few days later and they bled it correctly and got the pressure right and the light went off. The shuttle valve was off center causing the light to come on. You can unscrew the switch (slowly, there is a spring and pin in there) and look in the hole to see if the valve is off center.
Thread Starter
Intermediate
Joined: Jan 2014
Posts: 36
Likes: 0
From: Jacksonville Florida
Sometimes the shuttle inside the master cylinder gets off center and causes the switch to close and light the BRAKE light. That usually happens when you bleed the brakes and then it gets stuck in the off-center position. My light came on after I bled the brakes recently but it went off the first time I stepped on the brake pedal.
You could try poking something sharp down into the switch opening and see if you can align the shuttle. There is a groove in it that the tip of the switch fits into. The first picture in this post shows what to look for:
http://forums.corvetteforum.com/1585621532-post1.html
You could try poking something sharp down into the switch opening and see if you can align the shuttle. There is a groove in it that the tip of the switch fits into. The first picture in this post shows what to look for:
http://forums.corvetteforum.com/1585621532-post1.html
Intermediate
Joined: May 2019
Posts: 28
Likes: 1
Sometimes the shuttle inside the master cylinder gets off center and causes the switch to close and light the BRAKE light. That usually happens when you bleed the brakes and then it gets stuck in the off-center position. My light came on after I bled the brakes recently but it went off the first time I stepped on the brake pedal.
You could try poking something sharp down into the switch opening and see if you can align the shuttle. There is a groove in it that the tip of the switch fits into. The first picture in this post shows what to look for:
http://forums.corvetteforum.com/1585621532-post1.html
You could try poking something sharp down into the switch opening and see if you can align the shuttle. There is a groove in it that the tip of the switch fits into. The first picture in this post shows what to look for:
http://forums.corvetteforum.com/1585621532-post1.html
I realise this is an old post, but I'm having the same issue. Brake light is on when the wire is connected to the master cylinder - on all the time. Sometimes there's a brief moment when it goes off.
I can't view the pictures in that post - they are blocked? - but tonight I took out the switch carefully, and the spring. There's a needle type of thing connected to the switch that comes out, and it goes into a speherical (spelling!) chamber, but I can't see any groove. There's just a small circular opening for the needle to go into. Is it down this hole I can safely poke something very skinny? There's no way a screwdriver is going to get down there.
Cheers for any help.
Fred