The yellow ABS light is there to tell you something is wrong. If the red light is on, one of three things happened. The parking brake is not fully released due to sticking cables, the fluid level is low in the master cylinder, or the spring-loaded pressure differential switch is tripped and stuck in corrosion or gunk buildup in the valve body.
Sticking parking brake cables must be replaced. Lubricating them is never a permanent fix. Pull the parking brake pedal up. If the red light goes off but the ABS light doesn't, cycle the ignition switch off then back on to reset the system. If that's not the problem, you can often reset a stuck pressure differential switch by jabbing the brake pedal with a few quick hard stomps. To find out for sure why the red light is on, you can unplug the parking brake pedal switch, the fluid level sensor, and the pressure differential switch to see which one is causing the light to be on.
Did the lights come on before or after you replaced the brake parts? If after, you probably pushed the brake pedal down too far to adjust the caliper pistons out. That would trip the pressure differential switch. NEVER NEVER EVER push the pedal down more than half way, (unless it's a new master cylinder). Crud and scale builds up in the bottom half of the two bores where the seals normally don't ride. Pushing the pedal to the floor, like many do-it-yourselfers do, causes the seals to tear when they ride over that crap. Then you'll have a low pedal or it will slowly sink to the floor while you hold pressure on it.
If only the yellow ABS light is on, there is a problem in the ABS system. The most common is a broken wire to a wheel speed sensor. There is one at each front wheel, and one in the top of the rear axle. That rear one can get metal filings on the magnet causing a loss of signal. I've also seen corrosion in the two-wire connector on the left frame rail over the axle, and a melted wiring harness that was moved to install an aftermarket dual exhaust. ABS problems will not cause the red light to turn on.
If the yellow light is on while the system goes through it's two-second self-test, then goes off until you drive between a few hundred feet to a mile or more, suspect a cracked tone ring on one of the front wheels.
Wednesday, April 15th, 2009 AT 5:00 AM