What causes anti-lock brakes and shifting problems?

Answer by  wontyoubemynaber (24)

One thing that can cause both of these problems in General Motors cars is vacuum problems. Check for leaks in the vacuum hose and canister. This is the only thing that would cause both problems and repairing it should take care of both. If that doesn't work then the shifting problem the modulator valve and your brakes may need bleeding.

Answer by  kennethjgoodson (4903)

The shifting problems can be caused by the slave cylinder. It will cause it not to shift the right way. As far as the Anti lock brakes you should pull your wheel off and make sure the sensor is up against the hub. If it is not the anti lock brakes will not operate properly.