Spongy brakes - air in the ABS?

I bought my truck last year with crap brakes, but drove it like that for about 500 miles before having a chance to look at them (along with a crap ton of other work). I bought new braded soft lines thinking that would stiffen the pedal up. Come to find out, my master cylinder was leaking into the brake booster, so I replaced both of those with new OEM. I bench bled the master before installing. I also had to replace a number of hard lines on the truck (6 hard lines, 2 of which were connected to the ABS pump). I bought my new hard lines from Toyota dealerships already formed, and I had to wait about 2 weeks on one of the ABS lines (while the old busted one just leaked fluid out). I obviously bled the brakes after installing all the lines and the master cylinder (with a wood block under the brake pedal). Test drove the truck, brakes were very soft. I let a shop close to my home try bleeding the brakes ('m pretty sure they vacuum bled the brakes), and they did get a little more air out, and the brakes are a little better, still pretty spongy though. I did bleed them in the correct order and I spoke to the shop and they did as well. They think my ABS pump may be the issue and they can't get the air out of the pump (and think I need to replace it). Wouldn't I have an ABS light on if the pump was the issue? Do I need to find someone with TechStream that can activate the pump and pump the air out?

 

If the suspicion is air in the ABS pump, then yes. Some bidirectional scanners can perform this function also.

 

You 100% sure the rears are adjusted correctly, and LSPV is setup properly (and working)?

It's not a hard test to check the rears. Jack up a wheel and spin it, feel for resistance. LSPV is a bit more work to check.

 

@kentuckyMarksman i recommend reading @Aerindel’s post, reply #8 here, for things to check: https://www.tundras.com/threads/adjusting-rear-drums.62519/#post-1637779

pay careful attention to his last paragraph in that reply. It’s 100% truth.

 

I haven't checked the rears to see if they are adjusted properly, and I haven't checked the slack in the parking brake cable since getting it back from the shop yesterday. I did engage my parking brake 30 times the other day and could hear the parking brake engage and disengage in the rear each time. I will check that in a few days.

First thing I did after I got the truck home yesterday was adjust the LSPV, and I moved the adjustment to the top of the rod, that did help some. I am sure the LSPV does work. Before I replaced any brake parts I had to run a load of dirt to my mother in law's house and with the truck bed weighed down the brakes worked much better.

 

This speaks volumes right here and should be a big neon sign flashing in your eyes that your problem is in the rear of the braking system, i.e. brake components somewhere behind the cab*

 

That is interesting, I would not have thought the parking brake would have been a factor. That being said, I bled my brakes on my 18 Tundra (35K miles) last year, and the brakes became more solid.

 

Proper drum adjustment on the 1st gens is critical to braking function. Slack/soft/spongy pedal is a known side effect of ill-adjusted drums on these trucks. We have a sticky thread here in the 1st gen forum specifically covering rear brake adjustment for this exact reason.

It is what it is...

 

I'll check to see if the rears are adjusted properly when I get a chance. Do you think that's the likely culprit? The brakes working better under load was before I replaced any components, and everything I worked on was in the front. I didn't touch the rears apart from adjusting the LSPV. The shop that tried bleeding my brakes also turned the LSPV some (I did more after I got home) and they also disassembled and reassembled the rear brakes, but I haven't checked to see if they are adjusted properly since they looked at it.

 

Thanks. I'll check to see if the rears / parking brake are adjusted properly then I'll pick up a new scan tool that had the ABS pump function. My scanner is probably 13 or 14 years old and doesn't have that function, was thinking about getting a new one with more functions anyway.

 

I do think it's the main culprit to spongey brakes. But knowing your truck has some cancer on it based on your previous comments, check page #2 of that thread in order to verify everything is pivoting correctly for the p-brake stuff.

That would include checking the LSPV armature and its pivot points also. And I presume you bled the LSPV when doing all four corners (RR, LSPV, LR, RF, LF)

 

What shifty said and the link he provided is good. 1st gen and second gen are totally two different animals mechanically. I have both an 05 and 16 and do all my own maintenance.

 

@kentuckyMarksman will save you some hunting just b/c I had the FSM open a minute ago. Attached here is all the LSPV info for '05-'06 Tundras.

 

Thanks. When I check the rears I'll also check to make sure all the pivot points for the LSPV work as they should.

 

@shifty`
Quick update: the parking brake certainly has less resistance in it than before the shop touched it. I got under it to see it to take a look and there's a fair amount of slack in the parking brake cable. Seems the shop didn't correctly adjust it when they put the rears back together. Might be a couple days before I can adjust the parking brake, but I think that's going to be step #1.

Good news though, all the levers and components for the parking brake work and none of them are seized in place.

 

Sounds like it's the rear brakes, but just in case, one way to "bleed" the ABS pump is to get it to engage. Find a dirt road and slam on the brakes so it engages abs.

 

Brake hard on a washboard road = instant ABS cycling.

 

Problem is I don't know of any dirt roads. Nearest gravel road I know of is 20 minutes away

 

I don't believe this is accurate. I asked several times in the past when I was having all my brake issues and Empty Lord said that the software capable of doing this (Techstream) does not work on our trucks. There is no computer option.

The only way to try and burp air from the ABS lines on our truck is to do what others said and get the ABS to engage manually.

 

It doesn't have to be an actual gravel road. Just need to find a place that's got a couple hundred feet to work with. By my house there is a utility access road that has a 200 ft stretch of gravel. I used that in the past. Just look around the next time you're out and about.

 

Yeah, dug around some old TS threads and looks like the abs in these doesn’t interface with the computers the same as later models.

 

I agree with shifty and others. Get those rear drums adjusted. These trucks have the worst brakes (soft pedal with extended travel) when the shoes are spaced to far from the drums.

 

Well, I had a couple of minutes today so I jacked the rear of the truck up and spun the wheels. On the driver side you can just barely hear the rear brakes rub on the drum (and that's only if you spin it backwards first). On the passenger side you don't hear anything at all. Point being, my rear brakes are definitely not adjusted right, and my parking brake is also way out of adjustment. Hoping to fix the parking brake on Saturday then try to adjust my rear brakes.

 

Got the parking brake adjusted, then adjusted the rear using the parking brake. Test drove it around the neighborhood, had good brakes. Slammed on the pedal a few times going down the road and have soft brakes again. It activated the ABS and cycled some air from the ABS into the lines, will need to bleed brakes again and it should firm up. But want to drive it for a few days first and see if I can cycle the ABS some more first. Seems like good progress to me.

 

Double check that rear adjustment while you're at it. Maybe that hard brake shook something loose.

 

Double checked the rear brake adjustment yesterday, everything seems good. As you spin the rear wheels the rear brakes are just barely dragging on the drums.

I also cycled my ABS a few times yesterday on some gravel, doesn't seem like I'm getting any more air in the lines, so I think bleeding the brakes 1 more time and I'll be good (brakes are already better than my last truck).

Going to use a vacuum bleeder this time so my wife doesn't have to pump brakes for me (finally bought a vacuum bleeder to take care of this, and to flush brake fluid in my wife's Chevy).