abs and brake light come on

The abs and brake light come on only wen I release the brake pedal andwen I press the brake pedal they turn off... this happened after brake master cylinder replacement... need help guys im really scratching my head with this one..

This is on a 1990 mazda b2200 if that helps

First thing I'd do is to make sure there's a tiny amount of free play in the booster push rod/brake pedal pushrod.

Second would be to re-bleed the brakes. If you didn't flush out ALL the old brake fluid when you did this, now would also be a good time for that.

AFTER you complete Cussers suggested steps make sure you have enough fluid in your master cylinder and the brake light float is able to move up and down freely inside the master cylinder.

I just went through this when the new master cylinder I purchased wasn't designed for the float option.

Dan

PS. Make sure to manually/properly adjust the rear brakes BEFORE you bleed the system. This will make all the difference in your braking system performance.

I unplugged the connector on the proportion valve switch and brake light is no longer on but abs is on all the time but thats because the connectot isnt connected so it disablles the abs completly do u guys think that the proportion valve switch could be the problem? The system is bled properly and the truck brakes really good juss those dam guage cluster lights

Anyone? ?