: 2400x1350 px
: April 3, 2018
If the battery terminals are clean and tight, then the next item to check is drive belt tension. If the belt which drives the alternator is too loose, then the alternator will not produce enough electrical current to keep up with demand. Many modern vehicles utilize a single belt which drives the alternator and other accessories. This system usually also has an automatic belt tensioner which always maintains correct tension and is not adjustable. If your vehicle uses a wide, multigrooved or so-called "Serpentine" belt to drive the alternator, then it likely also has an automatic tensioning device.
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.