Toyota 4Runner How To: Brake Fluid Flush
Apart from worn brake pads and discs, another brake issue may be caused by the special fluid that runs the whole system (we are not talking about air brakes here) that degrades over time.
The brake fluid can absorb water from the atmosphere, lowering its boiling point which further leads to corrosion and contamination with small rust particles and rubber. Another contaminant can be the air that remains trapped in the brake lines due to improper or no system bleeding after the fluid has been replaced.
That is why you should replace the brake fluid from time to time and make sure you do it right. The operation is not complicated and it can last about 50 minutes or so, depending on your skill.
You can find the brake fluid flush tutorial for the Toyota 4Runner here at top4runners, where you will learn what tools you need and how to perform the task.