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Old 11-10-2019, 03:47 AM #1
Rancho5 Rancho5 is offline
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02 Sport: Fixin to replace ABS/Master Cylinder Unit & need bleeding advice. Scantool?

Symptoms: Prolonged motor cycling-whirring sound upon startup. Squishy brake pedal and rig lurches forward when almost at a stop, while making motor cycling-whirring sounds.

Physically inspected all connection harnesses at the ABS unit as well as speed sensors at each wheel and they seem to be fine. No breaks etc.

Picked up a complete ABS/Master Cylinder unit from a local guy for $150 so why not swap it out to see if it’ll help.

While researching bleeding procedures I stumbled upon the 4th Gen site and they seem to be split into two camps: normal bleeding procedure and those saying the ABS actuators had to be tripped via some sort of Toyota software and a special connector. Apparently if you leave the ABS unit alone you can bleed old school but if you replace the ABS unit, like I’m going to do, you need the software? Others say to just drive the car hard, brake like a lunatic to trip the ABS and then bleed.

If ABS actuators are not tripped and opened, air may accumulate inside the ABS unit itself?

Some say bleed fronts then rears, others rear first since it’s furthest from the ABS unit. Others say the front and rears are completely separate systems, with the rears being controlled by the ABS unit and software is needed.

I understand my 02 and the 4th Gen share similar brake systems so I’m wondering what to do.

What is the most effective way to bleed an 02 when replacing the ABS/Master Cylinder Unit?

Any clarification or simplification would be greatly appreciated.
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Old 11-10-2019, 07:52 PM #2
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Bleeding brakes normally is fighting gravity.... the bubbles want to float up...... Likewise some ABS units have high spots that tend to collect air when the system is breached and it is difficult to get the flow rates high enough during normal brake bleeding to move the air.

Haven't tried this on the 4Runner but I have done this on other cars. I have a large syringe. I fill it with brake fluid with a small piece of tubing and hook it up to the front wheel cylinder / caliper brake bleeder port. I push the fluid up in to the caliber all the way to the master cylinder..... and now you are not fighting gravity.... the air is moving in the right direction. Shut the bleeder when you finish pushing the fluid in so that it doesn't drain back out. Might have to use two or three syringes full if there is a lot of air.

I do know that it is a great way to prime the master cylinder after replacement.

So if you continue to struggle and don't seem to be getting the air out normally this might be something to try.
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Old 11-10-2019, 10:27 PM #3
cahilc cahilc is offline
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Found ya' an awesome video. Cudos to Tim! @mtbtim

Brake bleed:
https://www.youtube.com/watch?v=rnyK3V-OGn4&feature=youtu.be

And another one on the motor replacement.

Motor replacement :
https://www.youtube.com/watch?v=E5NoyVjZAWo&feature=youtu.be

Diag sounds like MC seals and motor/vacuum pump. Any CEL codes?

If you replace the MC/ABS unit would be prudent to flush the ABS box as well. Will need either the SST (special service tool), bi-directional scan tool, or software/hardware to access the ABS solenoids.

Possible to bench bleed the MC?

There may be another way to open the ABS box to be bleed/flushed. Driving like a lunatic?

There's a wealth of knowledge on this board and I'm sure more knowledgeable will chime in to comment.

Caveat: ABS solenoids may be sensitive to being active to long (>2 seconds?) burnout? And be careful not to bottom out the brake pedal (internal MC damage?) Might be internet folk lore but does seem very prudent.

Trick is to push gently but firm on the pedal when flushing. Open the bleed screw, push out fluid, close bleed screw, repeat. Maintain MC fluid level. Edit: In the pushout of fluid cycle the abs solenoids. Cycle through each wheel. Two person job. Not rigorous pumping action. Theory being helps push out the air bubbles. Rigorous pumping (vibration) helps the air bubbles relocate and/or puts air bubbles in the brake fluid. There's also a vaccum method. Apply vacuum to top of fluid reservoir to help pull out the air bubbles.

Have a good backup plan for the flush. Doing this 'shade tree' might have to have several goes at it before firm pedal.

The brake line routings have been changed over the years. Hence the start at furthest, longest line first.

01-02 have individual lines to each wheel. 4 channel ABS. Maybe earlier models too.

Of course line wrenches and be careful on torque when tightening bleed screws and brake lines.

There's supposedly a MC rebuild kit for the seals ($?) and replacement motors ($?) available. Maybe rebuild your old unit if parts still available.

End note: Bleeding brakes seems to be more of an art form than an exact science. We're after the end product firm brakes. Some folks have difficulty with bleeding brakes/ABS units. Some 'ace' it everytime. Experience helps.

I've got an '02 Sport too. This is in my future. Bi-directional scan tool in hand. :P Hence the interest.

Hopes this helps and not to confuse more.

Cheers!

Last edited by cahilc; 11-11-2019 at 12:56 AM.
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Old 11-10-2019, 11:45 PM #4
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Reverse bleeding the brakes is another way of getting the bubbles out of the brake fluid.
I wouldn't do this to my rig and any other car/truck that I'm working on.
You risk pushing all that junk that is in the caliper cavity into the abs and master cylinder and creating more problems down the line.
In the end...it is your rig, do what you want.
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Old 11-11-2019, 10:52 AM #5
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Can someone please explain the role the ABS selinoid plays in the bleeding process? What’s it means that it has to “be open”, etc. Also the Bi-directional scan tool, it’s purpose and why it’s needed? I’ve bled many older cars, just nothing with “separate lines” and ABS solenoids.

EDIT: Called Autozone and they can loan me a scantool that will autobleed an ABS unit. $250 deposit. I'm gonna swing by to see if it actually bleed, and not just diagnose.

EDIT: Autozone scanner will NOT open ABS solenoids...

Someone mentioned a jumper tool? Anyone have any info on that? Don't wanna really buy a $200 scanner
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Last edited by Rancho5; 11-11-2019 at 12:39 PM.
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Old 11-11-2019, 11:05 PM #6
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I'll take a crack at this.

Simplified as much as possible.

ABS accumulator simply hangs out on the brake lines passively until the ECM/ABS module determines there's a wheel problem from the speed sensors. Then the ABS circuit (ABS accumulator 'box', ECM/ABS module) kick in to pulse the fluid (correct solenoids activated for specific wheel) in the brake lines to prevent wheel lockup and/or regulate the wheel speed.

The ABS accumulate uses solenoids to control the pulse. Hence there's brake fluid in there with the possibility of air bubbles. If the system is cracked open, yup good chance of air in the system. Sometimes you get lucky.

To purge the air need to bleed the ABS accumulator. Activate the solenoids during the flush. Some ABS accumulators have a specific bleed screw. The unit your swapping pretty sure doesn't.

Bi-directional scan tool. Enables two way communication with the on board systems. Some are better than others. Some mimic bi-directional. All scan tools want to be bi-directional or wish they could be.

Most non factory scan tools operate with some percentage drop from 100% of a factory unit.

Sorry but didn't mean to 'bait' you. ABS seems to particularly hard for scan tools to connect and be bi-directional. Doubt there's a good cheap ABS bi-directional tool out there. Maybe, would love to find a good cheap one and toss in the truck tool bag. Still looking.

Don't worry about brake line configuration. There's a specific pattern to bleed for your truck. Do that.

For the ABS accumulator to be purged need to open the solenoids during the flush process, one at a time, four total. Seems to require your basic standard flush first and then do a second flush to go after the ABS accumulator.

Techstream (Toyota factory software?) runs you through a basic flush first the goes after flushing the ABS on a second pass. Also of note it activates the ABS solenoids for 4 seconds with a 20 second cool down. So in those 4 seconds need to be pushing fluid through to flush out the specific solenoid.

-----
So here's a "basic" outline of the process. (super simple)

1. Swap in the MC.

2. Do standard flush/bleed all four wheels sequence vehicle specific.

3. Using scan tool, open one of the four ABS solenoids, bleed that line (wheel specific) 4 second interval of open for the flush, 20 second solenoid rest, cool down. Repeat for each wheel. Sequence vehicle specific.

4. Check firmness of brakes. Repeat from #1 if required.

----

Per chance would you have a mechanically inclined friend with a good bi-directional scan tool open to barter? Six pack of beer, steaks on the grill for bribing that sort if thing.
;)

I'll admit I've been looking for an affordable bi-directional tool for carry in the truck. No dice. The bigger units are not only more capable but more spendy. Not interested in the 'ooops, accidentally lost it' possibility for a spendy unit.


Yes there appears to be a jumper tool to activate the solenoids. Somewhere. Be cognizant of the 4 seconds open, 20 seconds cool down cycle.

Cheers!

Last edited by cahilc; 11-11-2019 at 11:08 PM.
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Old 11-11-2019, 11:47 PM #7
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Thanks so much for taking the time to write this up. Really cool of you and it makes sense now. I think your reply will help many others in the years to come.

On the off chance I can’t get a bi-directional scanner (looking more and more plausible) I called the local dealer to get a price on a brake bleed. When I told them I was replacing the ABS unit so the whole system would be open, and that they’d need to bleed the ABS unit, the service manager was confused. Said he’d never heard of doing that. “We just flush it and bleed it”. Any talk of solenoid bleeding was met with confusion. So I called a reputable independent place in town. Similar response and he said he used to be a Toyota certified mechanic for 20 years, and never heard of it. But he did quote me $119 for a fluid flush and bleed. “We’ll do what it takes and won’t charge you any more but I do want to see the car first”. So I may be taking it down to let him take a look see.

Anyone know where to get, make, and use a jumper?
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Old 11-12-2019, 12:01 AM #8
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I was checking out this scanner, not a bad price, when I noticed in the fine print that it works with Toyotas...2003 and up... search continues.

Found it! Same price as the dealer to bleed and I won’t get sucked into other “needed” repairs.

https://www.amazon.com/FOXWELL-Scann.../dp/B07CSMJJK9
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Old 11-12-2019, 12:29 AM #9
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@Rancho5

May work. Same brake system.

Any chance to try(demo) before buy?

Which one?

Last edited by cahilc; 11-12-2019 at 12:32 AM.
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Old 11-12-2019, 12:53 AM #10
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Quote:
Originally Posted by cahilc View Post
@Rancho5

May work. Same brake system.

Any chance to try(demo) before buy?

Which one?
Yeah, forgot to paste link. Found one that’ll work tho, link below.

https://www.amazon.com/FOXWELL-Scann.../dp/B07CSMJJK9
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Old 11-12-2019, 01:16 AM #11
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Quote:
Originally Posted by Rancho5 View Post
Yeah, forgot to paste link. Found one that’ll work tho, link below.

https://www.amazon.com/FOXWELL-Scann.../dp/B07CSMJJK9
Looks good. Pages #26 & #27 of interest in the user's manual.

Special Functions - Foxwell NT630 Pro Manual [Page 26]

Might be worth calling Foxwell tech support to see if it will hook up with an 2002 Toyota brake system. Same as 2003.

Worth the call as these will usually get a *lot* of vehicles but will skip weird ones.

Want to sure on what you exactly need for your vehicle.

I. E. Doubt it does 100% ABS function bi-directional for all the vehicles listed in the advertisement.

Will do most. That's the problem with these lower end cost units. Truth in advertising.

Then there are other units (next price increment up) which simply clone the auto factory software and bundle it up. (software liscence infringement?)

This is where the fun begins.


Good chance.

Last edited by cahilc; 11-12-2019 at 01:38 AM.
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Old 01-10-2020, 02:09 PM #12
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I'm going through a similar issue where the motor kicks on while driving and when i release the brake pedal I get this noise insidecab.mp3 • Droplr
I just tried to replace the accumulator/motor with one that was refurbished the thing that was weird about it was I didnt bench bleed the MC before I reinstalled it but during bleeding numerous times and also doing it with a snap on scanner I was never able to get all the air bubbles out so I didnt know if that was a result from me not bench bleeding it, and also the next day that crazy squel/screech sound was back so IDK if that refurb motor/accumulator was bad because it didnt make that noise at first or if this sounds more like a bad MC Trying not to spend 3k if I dont have to. Ive searched other threads and seems like its hard to tell if its the MC or ABS motor but trying to get this thing back on the road. Any help would be appreciated
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Old 01-10-2020, 05:12 PM #13
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See if this video helps...

https://youtu.be/E5NoyVjZAWo

Cheers - Cahil

P. S. Good chance the replacement motor is bad. Sounds like the motor has switched polarity and is running in reverse.

As to the brake bleed I'd press (continuous) on the down stroke as opposed to pump. Block of wood under the pedal to stop bottoming out the MC if so desired.
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