Three problems related to brake master cylinder have been reported for the 2005 Toyota Tundra. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2005 Toyota Tundra based on all problems reported for the 2005 Tundra.
I pulled my truck out of the garage (it was backed in) and when I approached the street applied the brakes. The brake pedal went to the floor and the truck barely stopped before entering the street. (driveway was luckily on flat terrain) I checked the brake reservoir and it was almost empty. Filled up reservoir, pumped brakes to get stiff pedal and checked for leaks. Could find none so drove truck on about 5 mile roundtrip. Pulled truck out the next day and reservoir was again empty but could find no fluid on concrete in garage. Filled reservoir & brought to my mechanic. He found that the booster pump was leaking into the master cylinder which was why there was not fluid on the concrete. He had to replace the entire unit since Toyota does not sell the components separately. This could have been disasterous under different circumstances. The brakes had worked perfectly fine the previous time the truck was driven. In fact it was driven over 250 miles on a hunting trip through roads that ran along cliffs. If the brakes had suddenly failed just 4 days earlier, someone could have died.
Brake fluid low-Toyota service center said master cylinder was leaking onto vacuum pack thus both had to be replaced, an extremely expensive repair that should not be necessary on a low-mileage vehicle.
Everytime I came to a stop light or sign, the brakes would lose pressure and then the car starts going through the light, while I am still holding the brakes. The would also lose pressure to where I could not stop in the middle of a hot day. Problem was consistent first thing in the morning on the way to work. Took it to Toyota dealer and they could not figure it out at first. They had me replace the brake pads, and rotors and bleed the lines numerous times. This still did not work and they said I needed a new master cylinder/brake booster. This assembly is all in one so the whole unit had to be replaced costing over $2,000 for the parts not including labor. The truck is a 2005 Toyota Tundra with only 60,500. They told me I was out of warranty and had to pay the cost because they have never heard of this failure before.