With ABS, sensors mounted at each wheel monitor the speed at which the wheels are turning. If one is turning slower than the others during braking, that indicates it is locking up, which could cause skidding and loss of steering control. ABS is supposed to intervene by rapidly "pumping" the brakes at the wheel that is locking up, allowing it to spin so that the driver retains braking and steering control.
Here's what causes this: A blown fuse for the system, A wheel-speed sensor that is damaged or covered by road grime, A broken wire between the sensors and the ABS controller, An ABS controller that has stopped working. A pump and valve that apply the right amount of brake fluid pressure to each wheel to prevent locking can also trigger an ABS sensor warning light when those items go bad. If the red warning light for the regular brakes comes on, that typically means your vehicle is losing brake fluid or the brakes are so worn that you don't have normal stopping power. Either of those situations warrants immediate attention and possible repair work.
In case you don't know who take your car to for auto electrical repairs, you can ask for references from fellow motorists; ideally friends and relatives who are unlikely to mislead you in this (potentially sensitive) matter. As long as they have faced such situations before, they are likely to guide you on which service providers to visit; or at least which service providers to avoid.
Sometimes, what people bother so much about turn out to be problems whose solutions are extremely obvious. This conversely means that checks for electrical problems in cars should start at the most obvious locations; the battery being a good example. Sometimes, a case of a car failing to 'start' or something of that sort could be simply as a result of an electrical contact breakdown at the battery. Here all that is required in the name of auto electrical repairs is something as simple as filing the terminals that connect the car to its battery.