Locating brake lines on your car is an easy task in most cases. In the event that the car has run over something that may have damaged the undercarriage of the car, or if the brake pedal goes to the floor, checking the brake lines is a must.
Check the brake lines by putting the car on a lift so that you can see them. If you don't have access to a lift, jacking the car up and putting jack stands under the car will suffice.
Start from the master cylinder that is usually located under the hood on the driver's side, or by checking the lines from each wheel.
Check the master cylinder for its fluid level. If the fluid is low, you have a leak somewhere. Generally, fluid level doesn't drop unless your brake shoes or pads are especially worn. Make sure to add fluid so that the cylinder is full and replace the cover.
Look at the master cylinder. If the cylinder is wet in any area, change it. However, if it isn't leaking, that still doesn't mean it is working properly.
Travel down the undercarriage of the car and check the line to see if it's leaking. Sometimes running your hand over the lines is necessary because brake fluid is clear and hard to detect.
Follow the brake lines on both sides of the car to the wheels. The usual places that leaks develop is at the juncture where the lines attach to the wheel cylinders. Check the wheel cylinders for leaks. If they're wet, they need to be replaced.
