Brake line faiure

Possible, assuming it's working.

This is your only "100% fool-proof" method, since you have no parking brake - assuming your later model has the parking brake adjustment.

But note, spongy-ass brakes can be due to numerous things:

• failure to bleed the LSPV,
• failure to bleed in proper order (PR, LSPV, DR, PF, DF),
• doing stupid shit like pushing the pedal all the way to the floor while bleeding (can blow out MC/booster seals),
• not having your LSPV adjusted properly so you aren't working the rear brakes at all (or LSPV is dead/failed!),
• if you have VSC (here's how to tell), it could be related to not properly bleeding for that system, I dunno...

There are a number of adjustments you can make to the rear, like adjusting the LSPV bracket further up on its mounting rod, that could legitimately improve your braking significantly by shifting braking more to the drums, which significantly improves braking feel.

The brakes in these trucks don't just naturally "suck". They're way the hell better than any GM truck I've owned, and I've had several.

 

Thanks 4 responding shifty. Could u please expand the acronyms..PR, LSPV, DR, PF, DF),? thanks. I know LAPV is the proportioning valve? I'm taking the truck in this wk to a shop where a guy works that seemed to know a ton about what u guys have taught me thus far. He said bleeding the LSPV was a bitch.

 

He replaced my front rotors and pads last yr. After he did that, the brakes felt better than they ever have since I bought it.

 

I think we have terms mixed up here. There's no way anyone is putting brake line pressure on the reservoir -- it would blow it apart. There's pressure bleeding -- which almost every shop in America has the tool to do. And I could see why a shop would leave pressure (20-30psi) on a reservoir for an hour for bleeding and testing. Then you're mentioning "pressure testing" -- I've never heard of any shop pressure testing brakes.

 

LSPV - Load sensing proportioning valve
PR - passenger rear
DR - drivers rear
DF - drivers front
PF - passenger front

bleeding the LSPV is just like bleeding any other part of the system. There’s a bleeder on it, I recommend pumping the brakes or using a pressurized bleeder. It does a better job of forcing the air bubble out. Tapping the LSPV during the bleeding may help loosen stubborn bubbles.

 

If they're knowledgeable, you may want to have them validate the LSPV is still good.

But also, the adjustment I linked to may actually help significantly with your braking experience.

 

Tvpierce, That's probably what my brother was referring to. The pressure bleeder. He said it was under 40 psi.

 

I should also correct myself for what the shop said to me yesterday. He said it was difficult to get all the air out out of the LSPV. That's what he meant by saying it was hard to do.

 

I almost wanted to hug the mechanic yesterday because I think I finally found someone who knows these trucks and how the brake system operates. He did also say that a mushy brake pedal may definitely be related to rear brakes being out of adjustment. He also mentioned the VSC. So from what I read, no VSC selector button, no VSC? I'll also look for the little canister near the brake booster. Wish I could buy u guys a round at the local watering hole for all your help. Or at least a happy meal!

 

I fixed mushy brakes in my other non-Toyota vehicle by bleeding them at the calipers and engaging ABS inlet/exhaust valves via dealer's scanner for that line. One corner had a huge air bubble escaped.

 

You can't apply that much pressure to the reservoir. It is definitely not anywhere near a brake line pressure.

 

Yup look for the can/keg next.

If we didn’t have places like this to share and swap thoughts, we’d be screwed, at the mercy of locals who may or may not know anything about what we got. Can’t have that!

 

No can/keg on mine. Here's some pics of my LSPV. The last guy who worked on my brakes must have installed a new bleeder valve on it and replaced the bracket. You can see a tiny bit of brake fluid on the outside. Not sure if that's leftover from them bleeding it or it's actually leaking. I wiped it off and I'm going to drive it 2day and chk it. I also sprayed down all the Ebrake components with PB blaster. The cable adjuster under the drivers side about half way forward from the rear looks pretty rotted. Definitely could fail if I attempt to use the Ebrake. I have one question. Is it true that backing up a vehicle with drum brakes and slamming down hard on the brake pedal will actually will cause the rear adjusters to move, thus adjusting the shoes? I've replaced the rear shoes on this truck and I don't understand how that would even do anything.

 

The adjuster

 

Have to use the E brake to get the rears to adjust. The way the rear drum shoes engage can be seen when you have the drum off. The wheel cylinder is located at the top and presses outward on the upper part of the pad. This wears uneven by design. The E brake cable actuates the pads at the bottom. Engaging the Ebrake moderately and then backing up and using the brake pedal to actuate the wheel cylinder causes the pads to rock or shift position slightly. This allows the adjuster to ratchet forward a notch. Doing this several times will manually move the adjuster. Once in adjustment, using the Ebrake alone will usually be sufficient in keeping the brakes adjusted without having to repeat the backing up process. Problem is, they had a redesign on the adjuster and starwheel due to poor performance. So this technique may or may not work for you and then a true manual adjustment of the starwheel through the plug in the backplate is needed. Put the truck up on jacks, spin the tire and listen for drag. Adjust the starwheel until slight drag can be heard. Repeat on the other side. I do this at least at every oil change and grease all my driveline zerks as well.

 

The cable adjuster

 

Looks suspect

 

KNA, so I will be moving the adjuster UP with a screwdriver to adjust the shoes, nobody ever mentioned the part about applying the Ebrake in the process of doing this.

 

What I'm referring to...Engaging the Ebrake moderately and then backing up and using the brake pedal to actuate the wheel cylinder causes the pads to rock or shift position slightly.This allows the adjuster to ratchet forward a notch.

 

Watch the video by @Tundra2 in this thread. The parking brake alone moves the adjuster when activated. Simply backing up won’t have the same action.

 

At least we know it does on earlier models. I am not 100% sure it does on later models, unless they moved the extra auto-adjust arm to live invisibly under the main arm in newer models. It’s definitely not mounted superficially in my 2006.

 

The adjuster arm is between the pads and the backing plate on the later models. Sort of hidden.

 

Ok, that’s what I was suspecting the other day when we were talking about it then. I’ve been meaning to dig into my brakes to confirm next time the rears are off.

 

The adjuster is on the diagram blow up and was visibly in the pics posted the other day. I uploaded one with the adjuster circled to point it out. Drums have to have an adjuster.

 

https://youtu.be/1fGZTmzlxWk?si=3hTAnloX68ZvJjFe

 

Adjuster required, yes. Self-adjusting arm ... there are a number of ways to make p-brake function without having any interaction with adjusters via self-adjusting arm.

 

Got the truck back and the brakes are much better. They bled the rear lines and adjusted the rear brakes. Guess I'll just have to get in the habit of adjusting them like every oil change like someone mentioned earlier. They pulled the drums off and checked the shoes, I was the last one to replace the shoes and I wanted them to chk if I had screwed something up. They said everything looked ok.