Brake light work go off?

Hey all,
I'm new to this place some of you were nice enough to
welcome me here a couple of weeks ago. I have a 1998
riviera with all of the options. If been working to get her back
in good order recently. I put in new struts/mounting plates
new plugs new air cleaner, cleaned my MAF new speakers
fixed my power antenna new rear sway bar end links
the list goes on. I changed fluids today. S/c oil, tranny fluid and filter,
power steering fluid and brake fluid. Oil was changed recently
and coolant was done in the last two years when I had my
water pump replaced. My neighbor and I have done all of the recent work.
He removed the old brake and power steering fluids with a
small hose and hand pump. Power steering went fine, but after
we filled the brake fluid and started the car the brake light would not turn off.
After putting the car in drive the car begins to constantly chime.
It's the same red light that comes on when you e-brake is on.
I took it out for a ride and the brake pedal pressue feels the same and
the car brakes normally. I even drove through the sand and brakes hard to see
if the ABS engaged, which it did. Any ideas? It's almost like the car thinks
there is not enough brake fluid in the system, but it's full. There are no visible
fluid puddles on the ground. I unplugged the sensor on the bottom right
side of the brake fluid resoivoir and the chime stops, and the light went out.
No ABS lights are on with that harness plugged in or out. I used prestone synthetic dot 3 brake fluid, from a new bottle. This is the same fluid that was in my brakes before. Anyone know why this light/chime is on?
Also does anyone know if the sensor on the right side of the brake fluid resovior
does anything besides moniter the fluid level? Is it ok to drive with it pulled out?
Or does it have any other function? Any help would be greatly apprecieated. Sorry for the long post I'm just trying to let you all know as many details that I can while it's fresh in my mind.

You probably got some air in the lines and need to bleed the brakes.

Thanks Derek I will start with that.

i dont know all the functions of the level sensor, but i dont think unplugging it will make the light go off.
sounds to me like the float is stuck. try tapping on the reservoir to make the float free.

Consider replacing brake fluid by bleeding out thru wheel cylinders to remove trapped air and replace enough of the fluid to make a difference. The Riv has small lines, most of the fluid is in the wheel cylinders and then either the ABS pump or the master cyl reservoir IDK which.

THere is a write up for a power bleeder (made from a garden sprayer) elsewhere on this site, that you might want to try.

The brake fluid reservoir sensors usually don't go bad to the best of my knowledge, but you ought to consider replacing the master cyl and reservoir at between 120,000 and 150,000 miles as you're hitting their design life. With better maintenance (fluid changes) they will last longer but not forever.

Albertj

Mr.Riviera wrote:

i dont know all the functions of the level sensor, but i dont think unplugging it will make the light go off.
sounds to me like the float is stuck. try tapping on the reservoir to make the float free.

If the sensor shorted somehow, it's possible that the lights would go off if unplugged.....

Have you tried removing and cleaning the sensor.
They can accumulate a film on them overtime that will affect their operation.
Otherwise try replacing it.
Switches and sensors are known to go bad when they have been disturbed, Such as in your case.

I have to disagree with the brake-bleeding advice and agree with Rick: the level sensor has been disturbed and is now stuck in the on position.

Because of the ABS this Brake light does not monitor pressure imbalance like a traditional system, with a sensor in the proportioning valve which will turn on the light... Low fluid or an un-released parking brake are the only conditions that will light this light. Therefore, air in the lines could not be the cause of your light & chime.

The FSM brake section and schematic back this up...

If there was air in the lines, the brake pedal would not feel normal. Therefore, I do not suspect air is causing the problem. It seems like the sensor needs attention. Your symptom is exactly the same as if you had low fluid, but you have verified level is full. Must be the sensor.

AA wrote:

If there was air in the lines, the brake pedal would not feel normal. Therefore, I do not suspect air is causing the problem. It seems like the sensor needs attention. Your symptom is exactly the same as if you had low fluid, but you have verified level is full. Must be the sensor.

A little air in the lines will trigger the sensor, and wouldn't affect the pedal feel very much.

I was just working on a '99 Grand Prix with the brake light on, and we sucked out the reservoir and refilled it two or three times and the light went off. Plus we disturbed a whole bunch of little slimey things that started floating around in the reservoir. The old fluid was pretty dark and gross, and a little clumpy. Full system flush coming soon. Anyhow, the point is that replacing the fluid in the reservoir disturbed the gunk built up in there, and in this case cleared the brake light.

I'm going work on my car this afternoon. I won't have enough time for
a full brake bleed tonight but I'll try flushing and replacing the fluid
from the resovoir. I'll tap it and clean the sensor. I'll repost with results.

Make sure not to allow the reservoir to become empty. If air gets into the ABS system, you'll have an entirely new set of problems.

I plugged the sensor back in before leaving work today.
The light stayed off and no chime. I guess it just needed a couple of
drive cycles to reset. Seems like the problem
worked itself out. I'll keep checking though. Thanks for all the help
and speedy responses.

Yep, driving around for a while sloshed the fluid and freed up the float...

Once a year, I remove as much fluid out of the master cylinder as I can (with a turkey baster), and then refill with fresh fluid. I always have to tap the side of the reservoir with a small wrench to get the light to go off.

Usually once or twice per year I bleed the fluid out through the calipers with a vacuum pump, filling the reservoir gradually until all the old fluid is gone. I have not had the problem with the sensor, maybe because the reservoir is never allowed to go below about half empty.

AA wrote:

Usually once or twice per year I bleed the fluid out through the calipers with a vacuum pump, filling the reservoir gradually until all the old fluid is gone. I have not had the problem with the sensor, maybe because the reservoir is never allowed to go below about half empty.

More accurately, this devotion to preventive maintenance keeps the gunk from building up around the sensor in the first place...

Every year is probably excessive, but Aaron is right... If you're going to keep a high-mileage car, it's a good idea to invest in a vacuum-bleeder and suck fresh fluid through all the lines at the wheels, after you've replaced the junk in the master cylinder.

Over a decade ago (and maybe 5 or 6,000 miles) I flushed the whole system in my '69 Wildcat the old fashioned way (1 wrench and 2 people,) and the stuff that came out was pretty nasty... I just haven't done it to the Rivi yet.