Had to make a sudden stop the other day. Now my brake light is on and I can push brake pedal to the floor and brakes are weak. I also here a clicking sound when I push the break pedal. What is wrong

neither is bad. The proportioning valve is kicked and they can sometimes be a bear to re center. Here's the best way I've had success doing that. Before you try opening up any more bleeder screws you, 1)top off the brake fluid reservoir, 2) slowly pump the brake pedal, not all the way to the floor and without the engine running but with the key on, about 20 to 30 times. After you do that you very quickly hit the brake pedal very hard but not all the way to the floor. The repeated slow pumping of the pedal will very slowly put pressure into the line, even if it's air it will compress a little at a time and when you jab the pedal that one time at the end it will re-center the valve. Now here's the key. If the brake light is on it should shut off when that valve centers itself. That's when you must bleed the air out but whoever you have helping you tell them not to push the pedal all the way to the floor again or the valve will pop again. Open the bleeder to the caliper that had the blown line and then have them push slowly down on the pedal only half way to the floor and then stop pushing and hold position til you tighten the bleed screw. After you close the bleeder screw they can let up and do it again. If he pushes it to the floor and you hear a click that means the valve kicked again and you need to start over. Time consuming, yes but it works. I hope this makes sense. Sometimes it's hard to relay what I do to words on paper,.
Dale

master cyl

you definitely need to bleed the breaks

How to Bleed your Brakes by Yourself

check all brake lines and wheel cylinders for leakage. if no leaks its probably the master cylinder. symtoms are-- pedal will sink to floor when stopping or not. or master cylinder leaks from behind "it", and runs down brake booster. if booster goes bad the pedal will be very hard! good-day !

Hi oakleafwoodw, sounds as if the brake master cylinder has busted a seal allowing the brake fluid to leak by cylinder when you push the brake pedal giving you no or very little pedal pressure....it is located under the hood on the drivers side firewall, you will see all the brake lines attached to it , remove those and the two bolts holding it on,take it with you to auto parts store for a rebuilt one , they will keep your core for rebuilding, other wise you pay a core charge., verify that they have the one you need before hand, get a quart of dot 4 brake fluid, hook it up, and bleed air from the brake lines starting with wheel cylinders in this order Right rear......left rear.....right front.....left front...making sure to keep fluid level topped off in the master cylinder during the whole bleeding process or you will pump air into lines....OK!! caution: you should not drive it until you have good brakes!! you said they still work but if you had to stop suddenly ,it won't do it.

check brake light switch under dash next to brake pedal...it may be wore out..the switch turns brake lights on as you push the pedal to the floor.... push the pedal to floor a bit and push plunger on switch closed and see if brake lights go off..if so..replace that switch

I hope you have enough sense to stop driving it and stop added brake fluid

Lets review:

ABS Light is on--You may have an ABS System failure,do we continue to drive it, no
But you did,you said awhile
Spongy brakes--normal,I don't think so
Brakes go to floor--how many things can cause that,maybe 2
Emergency Light--now were in big trouble,no brake fluid
Added Brake Fluid---no fluids are consumed on a motor vehicle
any fluid loss is from a leak and requires repair
You never top off any fluid,don't need to

You have an older vehicle with rusted out brake lines
You need to buy brake tubing,cut,bend,flair and fabricate new ones
No vehicle in history, ever had brake lines made for replacement

What do you mean no brakes? pedal was stiff would not press down?, pedal went to floor? That needs to be checked. if there are no fluid leaks, I would suspect the master cylinder.

It is on the brake pedal under the dash,follow the brake pedal arm .

You have to bleed it on all 4 wheel