Brake Pedal vibration after removing brake lines-My Fix

EDIT: The following write up cured the issue for one day. The next day (tuesday) I fired up the truck to get in a quick 50 miles of Gear Break-In before work and the pedal vibrated from first start up. Seemed less intense but it was there intermittently during the whole drive to work. Will get back to trying to resolve it and will post any updates.
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EDIT: 5/21/21 Fixed. This is the procedure I used to fix the vibration.

Step 1. Bleed Brake Booster/Actuator using the "pushing on the brake pedal" procedure outlined below.

Step 2. Bleed the Master Cyl. using a Scan Tool and the Rear Left and Right Bleeder screws.

Step 3. With the ignition still in the on position from Step 2. Have someone apply pressure to the Brake Pedal. Maintain a steady pressure. Do not pump the brake pedal. Open up the Left rear bleeder screw. Fluid will purge out of the brake. Now with the Brake pedal still having pressure on it move to the Right Rear Bleeder screw, crack it open and it will purge automatically. Release Brake pedal and turn off ignition.

This procedure fixed my pedal vibration caused by Air in the Booster from me disconnecting my rear brake lines.

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Thought I’d share this in case anyone runs into a similar situation.

The vehicle is a 2017 TRD Pro. I bought a clamshell and rear diff with Yukon 5.29’s from East Coast Gear Supply.

When doing the Rear diff, I disconnected the rear brake lines. I plugged the lines with silicone plugs once they were removed. I did this because I didn’t want brake fluid dripping all over my work area.

Rear diff was installed than I moved to the front end and replaced the clamshell.

Once everything was bolted back together and torqued I proceeded to bleed my brakes with my Branick Power Brake bleeder.

Bled front and rear. Everything went smooth.

Drove home and noticed that almost every time I depressed my brake pedal it felt like a cell phone set to Vibrate mode was taped to my brake pedal. Note: My braking (power/feel) was normal. No soft pedal or anything sketchy just an annoying vibration.

This drove me nuts. Did a ton of online research and ran across a bunch of articles where people took their trucks to the dealer and the dealer said it was normal. Than I read another bunch of articles that said it cost $2500, $4500, $3500 to fix the problem because of a component failure.

I went back to the shop the next day and scanned my ABS system with my scan tool. For the Toyota I use a Autel Pro. No Faults Found.

I than looked at my diagnostic software and researched Brake Bleeding for the TRD Pro. (The Pro & the Off-Road share the same Brake System which is part of the Crawl Control System.)

The Bleeding procedure was crazy.

If you ever disconnect any of your brake lines you first need to Bleed your Brake Booster and Actuator. No Tools needed. You than need to Bleed your Master Cylinder, Scan Tool with Brake Bleed capability, Than you need to Manually (two person old school) bleed your brakes.

So I did the Booster/Actuator bleed:
Ignition On.
listen to the pump do it’s thing.
When it stops, ign. Off.
Depress the Brake pedal more than 20 times.
Ignition On.
Again, listen to when the pump stops running.
Ignition off, Pump 20+ times.

DO THIS 5 TIMES!

Than, Bleed the Master Cylinder.

Connect your scan tool. Turn on ignition to position II. Go to Brake Bleed. Do the brake bleed but only bleed the rear brakes. Most scan tools will run you through the the procedure. (I think you can find a scan tool on Amazon for under $100 that will do Brake Bleeding on modern vehicles.)

The tool will tell you when to crack the bleeder screw open and when to close it. The computer will actually open a solenoid to squirt the fluid thru the rear brake hydraulics. (Getting the air out)

Once the Brake Booster/Actuator and the Master cylinder are bled you now have to bleed the front brakes the old school way. Professional shop Power bleeder will not work.

Have someone sit in the truck, Pump up the brakes and bleed them the old fashioned way. Passenger side first than Drivers side.

My diagnostic software said to go to the rear afterwards but I didn’t since I already bled them from the earlier step of doing the Master Cylinder bleed.

(If the vibration wasn’t gone than I would have done it all over again including the rear calipers with the Old School bleed)

But. After a Saturday night and a Sunday of miserable Pedal Vibration Today (Monday) it’s gone.

I think the issue is that if the rear brake lines are opened and allow air to enter the system it directly correlates with the Brake Booster and the sensitive crawl control system. The vibration comes from the brake booster/Actuators electronic pump recognizing that the system pressure isn’t at the level it needs to be (due to a tiny amount of trapped air) that it constantly engages and brings the pressure up during normal braking situations.

Get all the air out of all the areas and all the sensors and crap are once again happy.

Hope this helps anyone that finds themselves in the same situation I did.

If their are spelling errors or if I did a lousy job of this write up, Let me know and I’ll try to help you out. I’m so happy my vibration is gone I’ve been celebrating with way too many beers so... Good luck, hope this helps.

P.S. Always keep an Eye on your brake fluid level while bleeding AND keep the cap on, it’ll shoot out if you don’t)

 

Thanks for the write up. Definitely not touching the brakes on this thing lol

 

Glad you figured it out. Nice write up.

Sad that a fairly simple system (brakes) has to be made so complicated with 'add ons' like crawl control. Even ABS makes it tougher for a DIY'r to have success with a simple master replacement.

 

Is the 5/21 edit the actual fix? I’m having the same issue after having brakes fail.

 

It is a bit confusing, but here's how I believe the timeline follows.

Monday, May 17th 2021: initial post.
Tuesday, May 18th 2021: added edit to say it only worked for 1 day.
Friday, May 21st 2021: actual edit/process that eliminated vibrations.

 

It was the fix for my issue. Brakes feel great.

 

Did you have the dealer do it being it needs the scan tool?

 

that’s what I was thinking too, thank you.

 

No. I have an Autel scan tool.

 

Sorry just realized you are the OP. Dealer keeps telling me it is normal. I’ve driven this truck 3 years and 4 others since 2010 , never had this issue. Is that tool the same Toyota uses?

 

When did the issue start? Did you work on the brake lines and then it happened? All I know is that after I disconnected my brake lines I obviously got air in the system and I needed to bleed the brakes but, You can’t just do a normal bleed procedure. The Tacoma (and maybe other Toyotas) have a special procedure that needs to be followed to a T. Also, it can’t be done without a scan tool that has the ability to bleed brakes. I use an Autel Scan Tool. You can google it. Some are spendy but some are affordable. Just make sure it has the Brake Bleed Function. There are many after market scan tools that can do this but I use the Autel. The dealer uses TechStream. You can download TechStream to your lab top but you will also need an OBDII cable to connect to your vehicle. I think it’s much easier to buy a scan tool that will work on multiple vehicles instead of going the TechStream route. That’s only half of the procedure though. Read my post and you’ll see that you need the scan tool for some of it and the instructions for what to do for the rest. I read a lot of posts when I was dealing with the issue that the dealer said it was normal. B.S. Your brake pedal should not feel like it has a phone set on vibrate on it. Total B.S. Infact, If you have time to waste, ask the dealer if you can test drive another Tacoma to see what the brakes feel like. With so many people modifying there trucks and working on the brakes I can’t believe more people haven’t been bombarding the internet with this info.

 

For shits and giggles, here are the instructions for full system bleed via Techstream. Bleeding brakes, as you found, can be a complicated task.

 

my brakes failed due to failed driver wheel cylinder exploding. Put new cylinder on, changed brake shoes because the tabs bent. Took it to dealer because of the vibrating. They replaced the actuator and thought it was fixed. It still vibrates. This is my 3rd Tacoma , I also owned a 17’ tundra and an Avalon. None of them ever did this. No car I’ve ever owned does this. This truck definitely never did this.

 

This is absolutely absurd

 

It can be if you have to bleed the actuators.