Brake warning light staying on

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Jun 24, 2018 | 11:54 PM

puzzigully

Thread Starter

Racer

Joined: Apr 2011

Posts: 367

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From: Congupna Victoria

Brake warning light staying on

Hi Guys,

bit of an Odd one....

When I start my 1987 Corvette, the red Brake warning light stays on.....for a long time (10 minutes), then goes out.

When its on, I check the handbrake is fully disengaged several times, checked the fluid level in the brake master cylinder, but everything seems in order.

I did it once before and seemed to stay on for a shorter time...maybe 5 minutes at most.

Doesn't seem to be dependant on brake application either - just goes out by itself...

Any suggestion most welcome!

Last edited by puzzigully; Jun 24, 2018 at 11:56 PM.

Jun 25, 2018 | 01:26 AM

VikingTrad3r

Oil Producer

Joined: Apr 2014

Posts: 9,360

Likes: 2,732

possible the tang that grounds the bulb in the parking brake lever is sticking. i had a similar situation in my 86 but mine would never go out.

other possibility is the sensor in the m/c bore is grounded out,

or the wires to these are grounded out. for the brake lever, the wire runds forward parralel to the drivers left leg then up the door jamb into the dash. not sure about mc wire.

Jun 25, 2018 | 08:12 AM

Kevova

Le Mans Master

Joined: Sep 2013

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From: near the thumb in the mitten

Do you use parking brake? If so, parking brake cables could be slow to return. May just need lubed.

Jun 25, 2018 | 08:25 AM

playsdixie

Drifting

Joined: Jun 2013

Posts: 1,590

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From: ft myers FL/Munising MI

I actually pulled the parking brake awhile ago , first time in years, and the light now won't go off...If I wiggle and screw with the lever a little I can get it off , but it comes back after awhile......learning to live with it...

Jun 25, 2018 | 06:42 PM

puzzigully

Thread Starter

Racer

Joined: Apr 2011

Posts: 367

Likes: 7

From: Congupna Victoria

Quote:

Originally Posted by Kevova

Do you use parking brake? If so, parking brake cables could be slow to return. May just need lubed.

I actually NEVER use the parking brake, but when the light stayed on, that was my first thought - so I cycled it a lot to see if it had any effect... nope...

Theres only two ways for that light to turn on isn't there?
1. Parking brake engaged
2. Loss of fluid pressure in hydraulic circuit...

The light wont go out when started and idled for some time..so that has to eliminate 2 doesn't it?

Unless the timer has decided it needs to count slowly?? (I'm assuming there's some kind of timer that keeps it illuminated when started?)

Jun 25, 2018 | 07:10 PM

Kevova

Le Mans Master

Joined: Sep 2013

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From: near the thumb in the mitten

Only because it's easier. Disconnect fluid level sensor and drive it. See what happens.

Jun 25, 2018 | 07:20 PM

puzzigully

Thread Starter

Racer

Joined: Apr 2011

Posts: 367

Likes: 7

From: Congupna Victoria

Quote:

Originally Posted by Kevova

Only because it's easier. Disconnect fluid level sensor and drive it. See what happens.

Thanks for the reply, but I'm not sure the 1987 has a fluid level sensor... the only sensor on the brake master cylinder is a pressure switch that activates when you lose pressure in one circuit when braking.
Unless I'm missing something (wouldn't be the first time!)

In theory (what a wonderful place that is!) that switch should not activate unless the brake pedal is depressed and there is no fluid in one circuit (front or rear) - that then (again in theory) will complete an electrical circuit that will illuminate the bulb.

Your suggestion is a good one though, as if the switch is "sticking", then removing the connector will prove it is the switch in the master cylinder causing the problem if the light goes out.

Thanks for your help!

Jun 25, 2018 | 07:21 PM

hcbph

Safety Car

Joined: Aug 2013

Posts: 4,424

Likes: 603

From: Minneapolis Mn

Mine was due to the microswitch in the parking brake handle. A little careful bending of the lever and the problem was fixed. The lever itself could be brittle due to age so if you try this, be careful.