Could be the switch
When anti-lock brake light comes on and goes off, it may be due to a malfunctioning wheel sensor. Another possible cause of this problem is a malfunctioning ignition switch.
check the brake fluid level. try filling to top. Get it fixed !
you need a new brake pressure differential switch
I have a 1800 vectra and the break light comes on when traveling then goes off, is this the brake shoes or pads wearing out.
Light is usually comes on, when there is a problem with pressure in brake lines. Inspect the brake fluid level, and check for leaks.
check your brake fluid level and fill with brake fluid to the top of the master cylinder reservoir.
with the park lights on both left and right side are lite. but when the brake is applied the right brake lights up and the left goes out(doesn't light up)
I am assuming you mean the dashboard handbrake warning light. On many modern cars, the handbrake warning light comes on when the brake fluid is low. The early indication of this is when the light comes on when going around a corner and then goes out once you straighten up. If the fluid gets really low the light will stay lit.
Low brake fluid in the master cylinder
Unplug one wire from brake-light switch(s) one at a time, if the brake light goes out then the switch you just unplugged is either failed (shorted) or mal-adjusted. If you readjust it make sure the brake light comes on just after the pedal/lever leaves it's stop.
this could be the cause of low brake fluid or that your foot is on the brake and it is indicating that the ABS is working.
Put some brake fluid in the master cylinder.