If the brake pedal sinks to the floor only when the abs unit activates then your isolation valves may be the problem.
Abs brake pedal goes to floor.
If you notice your brake pedal is soft you may wonder what part of the brake system causes this issue.
A brake pedal that feels mushy spongy or that slowly sinks to the floor when depressed can be best described as brake pedal sink.
1 leak from brake line or brake caliper.
One of the reasons is the brake system loses pressure from an external brake fluid leak.
Technically there are two main causes that would make the brake pedal sink all the way to the floor.
Reasons your brake pedal goes to the floor.
This lets the pedal sink to the floor.
Brake pedals can go down to the floor for various reasons.
Check your brake fluid.
One of the signs that your brake system is not properly functioning is the brake pedal being soft or spongy which means the pedal goes down to the floor when pushed.
If you step on the brake pedal and it has little to no pressure and goes all the way to the floor especially if you re getting no braking.
Low brake fluid level.
If this bearing goes bad it will allow the brake rotor it move back and fourth which pushes the caliper piston back into the caliper creating an air gap.
Axle bearings hold the brake rotor true without play while they both rotate.
The final reason for a brake pedal to go to the floor is failing axle bearing.
If it s low top it off to the mark on the side of the reservoir.
No brake pressure pedal goes to floor.