How to Diagnose and Fix a Brake Pedal Going to the Floor Issue
The following steps can be used to diagnose and fix the root cause of a failure in your vehicle’s braking system. As always, consult your vehicle’s factory-specific service materials before attempting any such repairs.
1) Check the Brake Fluid Level
Start by checking your vehicle’s brake fluid level. If the level is significantly low, top off the level in the reservoir until it reaches the “full” mark.
Use the correct type of brake fluid as specified in your owner’s manual. Typically this is DOT 3 or 4, although some vehicles may be compatible with DOT 5 brake fluid.
2) Check for leaks
If your vehicle’s brake fluid level is low, you should thoroughly check the system for leaks. This type of leak is usually not that difficult to identify.
Trace each brake line by hand, paying particular attention to the vehicle’s brake calipers, wheel cylinders, and master cylinders. If you can see fluid on the inside of your vehicle’s rear tires, this usually indicates a significant leak in the wheel cylinders. If there are any leaks, they will need to be repaired before proceeding.
3) Bleed the System
Now, bleed the vehicle’s brake system to remove any remaining air. It is recommended that you bleed all four wheel brakes, starting with the rear axle and working your way up to the front brakes.
4) Disconnect the vacuum supply to the brake booster.
If the issue with your vehicle persists, disconnect the vacuum supply line to the vehicle’s brake booster. If the problem resolves on its own, you will need to replace the brake booster.
5) Replace the Master Cylinder
If none of the above steps resolve your vehicle’s problem, a faulty master cylinder is almost certainly the cause. If in doubt, replace your vehicle’s master cylinder before attempting to bleed the entire system.
What to do if your brake pedal hits the floor while driving?
Frightened Driver
Above all, it is very important not to panic if your car’s brake pedal bottoms out while you are driving. First, you should immediately weigh your options and study the traffic in front of, behind, and next to your vehicle. Determine if it is safe to pull onto the shoulder and how fast you need to do so to avoid an accident.
Continue to slow down by taking your foot off the accelerator while staying in your lane. If possible, slow your vehicle to 30 mph before pulling onto the shoulder. If it is safe to do so, signal your intentions and slowly pull off the road.
Once on the shoulder, you should continue to slow your vehicle. With the emergency brakes applied, bring your vehicle to a safe stop.
If your brakes are not functioning properly, do not continue driving under any circumstances. This is extremely dangerous and there is a very real possibility of harming yourself or others. Instead, you will need to call a tow truck to transport the affected vehicle to a repair shop for professional repairs.