# 2005 Buick Lesabre Brake light on



## raylo32 (Nov 25, 2006)

The "brake" light generally indicates a failure in the brake hydraulic system. If one of the 2 hydraulic circuits has more pressure than the other due to a leak or whatever a switch in the master cylinder sets the brake light. You need to get that car to a mechanic... and be careful since you may have only partial braking.

The wires are probably to the ABS sensor. I don't believe that a failure with that would set the brake light but I could be mistaken.


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## ukrkoz (Dec 31, 2010)

cHECK BRAKE FLUID LEVEL IN MASTER CANISTER. iT HAS LEVEL SENSOR.


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## Old Thomas (Nov 28, 2019)

ukrkoz said:


> cHECK BRAKE FLUID LEVEL IN MASTER CANISTER. iT HAS LEVEL SENSOR.


Yea, as the brake pads wear the fluid level goes down.


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## HotRodx10 (Aug 24, 2017)

In my car the "BRAKE" light on the instrument panel indicates the parking brake is on.


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## deamer1 (Oct 17, 2018)

Thanks for the reply.
That was my first thought too.
Still working on it, will post results ASAP repairs completed.


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## huesmann (Aug 18, 2011)

raylo32 said:


> The wires are probably to the ABS sensor. I don't believe that a failure with that would set the brake light but I could be mistaken.


Yes. If the sensor fails, or the ABS computer doesn't get the right signal from the sensor e.g. cut wire or unplugged sensor, it will trigger a light. The computer is expecting the variable signal from the sensor interacting with the reluctor rings.


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## Brainbucket (Mar 30, 2015)

Is the ABS light on? Is the stability light on? That the light with a pic of the back of a car with squiggly lines behind it. If so, you need to scan it to get the ABS codes. Both of those lights are amber. Brake light is red. If no ABS lights, unplug master cylinder fluid level sensor, emergency brake sensor, and if equipped, proportioning valve. If light doesn't go off, scan instrument cluster to see if a command is sent to turn on light. If no command then you have a bad cluster. Just went through this on an Avalanche.:vs_cool:


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## bob22 (May 28, 2008)

Does the light go off/on when the e brake is off/on?


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## ukrkoz (Dec 31, 2010)

Older cars do not have separate indicator for brake fluid level. It is all same Brake light. New ones will tell you, if brake fluid is low.
So you still didn't say, if brake fluid level is good or not.
KISS. You can always complicate it.


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## raylo32 (Nov 25, 2006)

Oh, I know it will set some light for sure. Just not sure it is the "brake" light. That usually is reserved for a few specific issues... like to show the parking brake on, hydraulic circuit failure, etc. My cars since 1994 at least have had separate ABS lights.



huesmann said:


> Yes. If the sensor fails, or the ABS computer doesn't get the right signal from the sensor e.g. cut wire or unplugged sensor, it will trigger a light. The computer is expecting the variable signal from the sensor interacting with the reluctor rings.


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## huesmann (Aug 18, 2011)

Oh I see what you mean. Yes, modern cars with ABS have a separate ABS light (typically amber) and a Brake light (red). The latter basically tells you your parking brake is on, or your fluid is low. The former indicates an ABS system fault.


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## raylo32 (Nov 25, 2006)

You guys are still missing the point that the most important "Brake" warning light function isn't fluid level, it is alerting to brake failure due to one circuit either leaking down or having air in it. When this happens the differential pressure switch in the master cylinder moves and sets the "Brake" warning lamp. Slightly low fluid by itself isn't a big deal but when one circuit is low or aired up it is a big deal. See this diagram:

https://www.bing.com/images/search?...EDD75B&selectedIndex=1&FORM=IRPRST&ajaxhist=0


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