Wierd brake issue

My brakes are doing the wierdest thing. When i press my pedal theres normal pressure bit it only activates my rear brakes partially. Second press activates all of them normally.

 

Can you give us more details?

Like, what cab type? which engine and drivetrain? Last brake service? Do you live in a road salt state, where the truck is driven in salt regularly? Is fluid level fine? Which brake master cylinder/booster do you have? (pic, please)

We can only help you if you help us.

Sometimes, if you don't live in really salty places and your brakes are working, firmly setting/unsetting your e-brake can adjust down the rears. You may've noticed a sticky thread here in the forum about adjusting the rears. It's critical to braking.

 

Access cab with 3.4l v6. Standard transmission. Replace calipers as needed. Every few years. Brakes have been bled thouroughly. Oem master cylinder. Hoping its not my ecu

 

Rare vehicle worth saving

 

My rear ebrake is disconnected. My front brakes dont activate is the real issue

 

Correct braking on these trucks is heavily dependent on the functioning and adjustment of the rear brakes, actually. It's so critical that there's an entire thread dedicated to the topic of getting them dialed in correctly here. When was the last time you dialed in the rears, knowing your e-Brake cable is disconnected. And why is the cable disconnected?

Need a pic of the master cylinder/brake area under the hood.

There's one specific master cylinder on the 2000-2006 that has a seal which fails, and begins dumping fluid into the booster. It causes the issues you describe. Toyota doesn't sell new seals - you have to buy the whole assembly, which is a booster with a 2-part master cylinder. Just want to make sure you don't have that.

 

The biggger master cylinder is new as of last year. The small one has never been replaced

 

Doesn't look like the "unicorn" MC some folks have that's problematic.

And you're sure the vacuum line off the booster is fine?

Look, I'm not trying to harp, but the first thing I'd be doing if I were you is popping off the rear wheels and adjusting in the rear shoes.

And if you've bled recently, I'd be curious what method you used, and if you also bled the LSPV.

 

When i replaced the master cylinder last year there wasnt any fluid in

 

Ill try bleeding everything again. I was using another person pressing the brake and holding. My brother has a bleeder gun ill borrow

 

With these trucks you need positive pressure on the master cylinder while bleeding. A lot of guys use the Motive unit, or similar.

The order with which you bleed is important also. And I'd recommend also bleeding the LSPV (prop valve). It's back here, near the rear axle.

Bleeding order to follow is outlined here.

This thread also has good info about rear brakes adjustment.

 

Although we don't seem to see it much in here, Toyota brake calipers are notorious for seizing. Maybe check that out...

 

That was another thought: Pistons stuck or freezing. Gut is telling me something else, but we'll see I guess

 

Make sure and bleed the LSPV valve above the axle.

 

As noted....none of your brakes will work properly, if the rear brakes aren't working properly....and without a properly working E-brake....its hard to get your rear brakes working properly.

What you're describing, is pumping the brakes. The rear brakes work first, because drum brakes need less pressure to work than disc brakes do. So your first pump of the brakes, is making the rears work. The second pump is building enough pressure for the fronts to work.

You could have air in your brakes....or your rear brakes could be out of adjustment, which is finickier, and more important, than most people think. This is why the E-brake was designed to automatically do it for you. Its not just for parking.

 

+1

And even if you get the rear brakes adjusted perfectly now, with the parking brake disconnected they will become out of adjustment as you use them because the parking brake is the mechanism that self adjusts the rear brakes as they wear.

 

Small one should be for the clutch.
Your rear brakes are key here. Get them right and the fronts will follow.