99 Chevy Silverado z71
Abs light is on, break light flashes on and
off speedometer jumps around and causes
the trans to shift down. What could cause
Failure in the antilock braking system for the ABS light, an ABS code will be needed to find out what is going on with it, could be a bad wheel sensor. Inside brake warning light could be just low brake fluid or a park brake cable adjustment needs to be made, as you related the speedo with a trans shift problem that sounds like a transmission speed sensor erratic output.