Last December i put a brand new brake master cylinder in my 98 lesabre. I had previously tried a free used one. This new master had no reservoir. It started a beep on and off. Nothing wrong with how the brakes work. I tried switching the sensor. Did nothing. I assumed it was the reservoir was causing it. I didn’t change it until now because it’* a windows car. And I was afraid it would cause air in the line and would have to bleed it. So I waited till warmer and till I parked for summer.

it’* still beeping. The sensor is in the reservoir. So why would it still beep? Can the master cause this?

'I assumed it was the reservoir was causing it. I didn’t change it until now because it’* a windows car'

windows car???
What'* beeping?
Been to long.

I agree, especially this:

Ok I will try re bleeding it at master and so on

the beeping is like the door open beep but faster. The beeping is from the brakes and goes on n off.

Is the brake light blinking with the beeps?

No light does not blink. Tomorrow I may get at re bleeding it. I don’t see how there could be air anywhere. The pedal is very hard. But the last car I changed a brake master was a 72 impala years ago. Not so fussy back then.

What makes you think the beeping is related to the brakes?

Because the brake light always comes on with it. When the beeping goes off. Which is does 50% of the time the light goes off also.

I bleed by the master cylinder first. Then by the caliper. Did have a little air on the first bleed at the caliper. Then no air every after that.

the beeping did not stop after this.

it’* just a winter car. I think I’m just gonna let it be. Hopefully it will burn out.

the frame is getting bad. Might only go a couple more winters.

Scan the ABS module. There'* codes in there.

Is this something autozone or similar can do with their scanners?