ABS Issue

[XAlent]

Hey all,
My 98 HDJ101K has recently developed a very unwanted ABS issue. When moderately braking from anywhere around 30 mph to a stop as in approaching an intersection, the ABS will activate when there has been no lock up of any wheels. It's intermittent and I'm struggling to find a distinct reason for it occurring. I generally lift off the brakes and the ABS action will continue for a little after before ceasing. I have tried emergency braking on dirt roads and the ABS activates as it should. Many times on sealed roads even with hard braking it will not occur.

This has started after having changed all discs and pads (to an aftermarket one DBA) and installing flexible braided lines to each calliper. Callipers were cleaned and slides lubricated so they all function well. Brakes were bled old fashioned way, simply opening rear bleeders and allowing pump to push old fluid out. Fronts were bled with the pump, hold, open bleeder method. I have bled them twice again since this problem started occurring. I have bled the accumulator 3 times with the 30+ pump method which seemed to lessen the amount of times this problem occurred but obviously hasn't stopped it. At no stage during pad/disc/hose change or the bleeding the process was the reservoir emptied to a point where it would have drawn air. There is a much larger accumulation of brake dust appearing at the right hand side front wheel. I have changed both front ABS sensors for new ones but am now at a bit of a loss to find the cause of this issue. No ABS lights / buzzers appear when it happens.

Has anybody experienced anything like this or have some sort of idea where I should go from here?

Cheers

 

[100d ua]

I would recommend the following:

Replace steering rack bushings

Zero point calibration (best to use techstream)

If all that fails, install a VSC switch and just toggle it off.

I'm now realizing some of this may not apply for your specific model out of Australia. Not sure if you have IFS or SFA? Anywho, it would help to hook up to Techstream and check for any ABS faults.

 

[XAlent]

Steering rack bushes were replaced a month ago
It's a JDM model, IFS. Doesn't have VSC.
I haven't managed to get Techstreamto connect to it. Well I did, but the techstream I used didn't have the HDJ100 as an option so was was very limited in the data it saw and there was nothing regarding ABS on it

 

[2001LC]

I assume you have electric brake booster, not vacuum assist.

I don't know anything about 98 HDJ101K OBDII or zero point. So you'll need to study your FSM. If zero point calibration, is part of procedure (like in alignment). You really need this done.

Make sure wheel lug nuts are torque to 97ft-lbf.

You must have serviced front wheel bearing service, while replacing front rotors. Make sure the wheel bearings have zero play. If loose, they play havoc with wheel speed sensors as wheel hub wobbles. Loose wheel bearings, rotor may also wobble into caliper.



If wheels and wheel bearings all good tight.

Make sure to check ball joints & TRE (outer & inner) for any play.

Make sure you don't have excessive tension on ABS wires. Which can happen in lifted rig, where they pull on wires.

Sounds like to did a good job of bleeding. But did you check for air. i.e. IG key OFF, pump brake pedal 40 times. note: How many pumps until pedal pressure drops out. 24 is very good, 40 indicates weak accumulator, Assuming good fluid. ( I find I get best (least) pumps and shorts times, with Toyota brake fluid).
After evcuuating acumulor (40 pump). Use a stopwatch, time how long it takes for accumulator to pressurize (charge). IG key ON, start timing, stop timing when booster motor stops. spec is 30 to 40 seconds with 12.5Volts at battery. Over 40 sec., re-bleed.
(tip: do not let fluid level drop below low line).

If no air in system and time over 40 sec. with 12.5 volts. You may have brake booster issue.

Try this little test. IG key on. Pump brake pedal rapidly. See how many pumps, until ABS alarms sound off and dash warning lights come on. 17 pumps or more is good indicator, 7 or less pumps, not so good.

If all this checks out. You may have a fault in the ABS unit (Black box on side of brake master) Or even a seals issue within master. It is also possible the ABS CPU has a short or and wire to ABS unit or CPU. But I've have never found a bad CPU. But I find many bad master. Rule of thumb. Any issue with master, Replace the brake booster assy and master (the whole brake master)

I've had a master ABS unit, that locked up one rear ABS. The ABS unit has screen in it. If brake fluid not proper care for over its lift. Which a clue of: Is fluid usually has stained the reservoir. Old brake fluid, builds up solids, which damages seal and clogs screens. So staining, is a clue of health of master seal and ABS unit.

We must also consider the power (wires) to the master. Which starts at battery clamps. If current inhibited by corrosion in wiring. This increases resistance. I've seen this damaged ABS units.

Brakes ...... Overdue write-up.

First and foremost: Brakes should only be worked by those, with high level of mechanical abilities and experienced with brake systems. With the age of all 100 series today, in our aging fleet. Any issue, with brake master assembly. IMHO, best and safest course of action. Have the whole brake...

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Tip: The front OEM outer shims (anti-squeal) and fitting kit, need to be installed. Even when using aftermarket pads with anti-squeal shims attached. We still need the outer shims and fitting kit. As outer shims clips into pistons and the fitting kit holds shims to pads. As pistons retract, they pull pads off rotors.

 

[2001LC]

Brake reservoir is a clue as to health of master and ABS unit.

Staining indicate fluid not properly care for.

Sometimes they start puking (backing up) fluid.

This reservoir looks clean (no staining). But notice the center camber is fluid is high. This resevoir was cleaned, But screen within are clogged.

 

[XAlent]

Thanks for your detailed replied. I've read quite a few of your threads which led me to bleeding the accumulator and looking at other possible faults.
The vehicle has about 170000m on it. It is essentially the same as a HDJ100 and shares the same braking system as US delivered vehicles, electric booster.
It doesn't require zero point alignment, doesn't have VSC
Wheels are always torqued to spec. I run 1.25 Bora spacers and these are torqued then rechecked as well. Doesn't have huge lift and there was ample length in sensor cable when I changed them out
I replaced wheel bearings with Nitto bearings when replacing the discs. That all went smoothly and I've had the vehicle on a hoist several times since and can't feel any bearing play as shown in that video. Ball joints are good (replaced early last year) and there's only a very slight amount of play in inner tie rods. Has fresh steering rack bushes
When I bled accumulator it took 30 pumps for pressure to drop and the pump ran for 34 seconds on refill. Terminals at battery are clean.
I didn't use Toyota fluid
I haven't tried the test to activate the ABS alarm, I'll do that tonight. I'll also check terminals and voltage at the booster pump but the vehicle is in very good condition and well maintained, still will pay to check.
There's no real staining in reservoir, fluid has been changed about every 3 years.
I pulled the front pads and the anti squeal and fitting kit are attached correctly

I'll recheck for bearing play and I'm also thinking of swapping front callipers and seeing if the excessive brake dust follows the right calliper over to the LHS. I'll also recheck the plugs on the ABS CPU and rebleed the accumulator

 

[2001LC]

Thanks for your detailed replied. I've read quite a few of your threads which led me to bleeding the accumulator and looking at other possible faults.
The vehicle has about 170000m on it. It is essentially the same as a HDJ100 and shares the same braking system as US delivered vehicles, electric booster.
It doesn't require zero point alignment, doesn't have VSC
Wheels are always torqued to spec. I run 1.25 Bora spacers and these are torqued then rechecked as well. Doesn't have huge lift and there was ample length in sensor cable when I changed them out

I replaced wheel bearings with Nitto bearings when replacing the discs. That all went smoothly and I've had the vehicle on a hoist several times since and can't feel any bearing play as shown in that video

The video shows, supper loose wheel bearings. Any play and they'll need breakaway preload reset.

. Ball joints are good (replaced early last year) and

Great

there's only a very slight amount of play in inner tie rods. Has fresh steering rack bushes

** We've seen a few inner TRE, come unstaked. They feel very much like the TRE ball failing. It can be dangerous, as TRE could come out of rack.

When I bled accumulator it took 30 pumps for pressure to drop and the pump ran for 34 seconds on refill. Terminals at battery are clean.
I didn't use Toyota fluid

Sounds good.

I haven't tried the test to activate the ABS alarm, I'll do that tonight. I'll also check terminals and voltage at the booster pump but the vehicle is in very good condition and well maintained, still will pay to check.

There's no real staining in reservoir, fluid has been changed about every 3 years.
I pulled the front pads and the anti squeal and fitting kit are attached correctly

Sound good.

I'll recheck for bearing play and I'm also thinking of swapping front callipers and seeing if the excessive brake dust follows the right calliper over to the LHS. I'll also recheck the plugs on the ABS CPU and rebleed the accumulator

 

[XAlent]

@2001LC I've tried a few more things. Retightened both front wheel bearings, replaced rear ABS sensors (all have been changed now) and checked (unplugged and replugged) all abs ecu plugs

I did the "Pump brake pedal rapidly. See how many pumps, until ABS alarms sound off and dash warning lights come on. 17 pumps or more is good indicator, 7 or less pumps, not so good" and the alarm and ABS light activated after 19 pumps so seems to be OK?

I tried disconnecting the front sensors which as expected brought up the ABS light. I assume this would mean the ABS system is then disabled? The fault still randomly occurred so now I'm not sure whether it is a function of the ABS activating or not.

I'm very tempted to remove the aftermarket discs, pads and brake lines and replace back the factory ones to see if this eradicates the problem even though that's a fair bit of work just to try and rule all of those components out

 

[2001LC]

@2001LC I've tried a few more things. Retightened both front wheel bearings, replaced rear ABS sensors (all have been changed now) and checked (unplugged and replugged) all abs ecu plugs

If no DTC indicating a bad wheel speed sensors. Your old ones are likely good. So was not the issue.

I did the "Pump brake pedal rapidly. See how many pumps, until ABS alarms sound off and dash warning lights come on. 17 pumps or more is good indicator, 7 or less pumps, not so good" and the alarm and ABS light activated after 19 pumps so seems to be OK?

Yes. Sounds like good accumulator and seal in master.

I tried disconnecting the front sensors which as expected brought up the ABS light. I assume this would mean the ABS system is then disabled? The fault still randomly occurred so now I'm not sure whether it is a function of the ABS activating or not.

If ABS CPU detects most any DTC (code), not just brake related. It shuts ABS system down. DTC may correct and clear on it's own, in just seconds if no longer detecting trouble code. Meaning not all must be cleared. Which you may see dash lights. But these will not activate ABS braking.

So again I'll ask. Is this just dash lights, with actual ABS braking?

I'm very tempted to remove the aftermarket discs, pads and brake lines and replace back the factory ones to see if this eradicates the problem even though that's a fair bit of work just to try and rule all of those components out

Not likely a new parts issue.

Hey all,
My 98 HDJ101K has recently developed a very unwanted ABS issue. When moderately braking from anywhere around 30 mph to a stop as in approaching an intersection, the

Low speeds, are also low RPM. Alternator turns slower generates less power, especially if old weak. Voltage issues, can result in ABS lights, but would not activation of ABS braking. At least I've never heard of activation due to low voltage. Nor, can I think of reason it would.

"ABS will activate when there has been no lock up of any wheels."

Backing up a bit here:

ABS activation, happens when any wheel is turning (exception is wheel speeds, during normal turning) is at different speed than others. The ABS CPU see this, form input from wheel speed sensors. ABS then brakes, faster spinning wheels.

So to saying:"no lock up". Are you saying no wheel is being braked. It's just dash light coming on?
Or
Are you saying; ABS is braking (slowing vehicle). You hear the crunching sound of activation, and vehicle perhaps pull to one side or the other. Even though all wheels, were turning the same speed.?

It's intermittent and I'm struggling to find a distinct reason for it occurring. I generally lift off the brakes and the ABS action will continue for a little after before ceasing.

Are you saying: ABS system, is braking (slowing vehicle) even after foot is off brake pedal? Not just ABS light on dash?

I have tried emergency braking on dirt roads and the ABS activates as it should. Many times on sealed roads even with hard braking it will not occur.

This has started after having changed all discs and pads (to an aftermarket one DBA) and installing flexible braided lines to each calliper.

DBA rotors (disk) are very good disk and pads. I've never seen one with runout, out of spec. But, wheel hubs, transfer its runout to rotors disk. If wheel hub runout out of spec. Runout multiples, the further from center of axle. I've not seen runout so bad, it activates ABS (I've seen some very bad run out). But, If bad enough, at say just one wheel. Like FR. I suppose it could result in that pad and disk, running hotter than others. You'd likely see more brake dust at that wheel.


Tone ring needs to be in good condition. Wheel bearing tight, so that wheel speed sensors is not trying to read a tone ring that's wobbling. Oil seal, in correct, with flat side out.

Oil seal in backward, results false wheel bearing preload. Then as metal of seal rubs on inner area of knuckle spindle, it wears. Bearing loosen very fast.

Callipers were cleaned and slides lubricated so they all function well. Brakes were bled old fashioned way, simply opening rear bleeders and allowing pump to push old fluid out. Fronts were bled with the pump, hold, open bleeder method. I have bled them twice again since this problem started occurring. I have bled the accumulator 3 times with the 30+ pump method which seemed to lessen the amount of times this problem occurred but obviously hasn't stopped it.

The timing on how long booster motor/pump runs. Over 40 seconds with battery voltage about 12.4V. Is clue, air in system. Can also indicate a seal weep/leak or weak accumulator. I've also found, not using Toyota brake fluid, I get longer run times.

At no stage during pad/disc/hose change or the bleeding the process was the reservoir emptied to a point where it would have drawn air.

While flushing from rear, it's okay to let level drop below minimum, in reservoir. We then bleed, and must keep level above minimum during bleed.

There is a much larger accumulation of brake dust appearing at the right hand side front wheel.

As stated, could be a runout out issue. Can also be pad assemble issue.
Did you properly install the OEM outer shims in front calipers and the fitting clips? Many do not when using aftermarket pads.

The outer shims, grabs onto caliper pistons and clip o pads nearest wheel hub side of pad. The fitting kit, lock outer shim (outer edge, furthest from hub) to pads. Without them, pads will where faster. Pads ride on disk more so, than with proper shim install. They, connect pad to piston. Piston, pulls pads away from disk, as piston seal retacts piston (returns to relaxed state). If they're not installed properly, pads may wear faster. This could explain, more brake dust on one side.

I suppose it is possible, for a caliper piston to stick. But I've never seen this happen. Let's say front right caliper pads, rubbing disk most all the time. That disk and pads, would heat up more than others. Then as you brake, you get uneven braking from uneve heat. This "may" (i've never seen this), result in ABS (braking) activation, as that one wheel slow faster than others.

We have two different size shim kits. 98-02, fit the smaller pistons. 03-07 for the large pistons. Or so is case in the USA 100 series. Toyota increased front braking in 2003, with the addition of larger pistons in caliper. Mismatching calipers, from one side to the other. Say FR caliper is the updated (larger piston), and FL is the original (smaller piston). This would result, in one side braking more than other.

I have changed both front ABS sensors for new ones but am now at a bit of a loss to find the cause of this issue. No ABS lights / buzzers appear when it happens.

Has anybody experienced anything like this or have some sort of idea where I should go from here?

Cheers

If I understand correctly. This whole issue only began after you serviced wheel bearings and brakes (new DBA's). You then R&R some wheel speed sensors, due to ABS issue.

So it is more than likely, a procedural error during R&R. Not one of the part installed bad.

It is also possible you've a failing master. I've seen where ABS unit (black box on master) failing to deliver proper power to booster motor. These are usually form long term resistance issue in wiring, from battery to fuse box and on to master. This is almost always, due to acid corrosion. Sometimes, this can affect the ABS relays in fuse box, and on downstream to ABS, even booster motor. Other times, it just increased resistance at brake control wire. This is due to corrosion on it's leads, inside brake control wire boots (bottom of ABS unit and on booster motor). This can result in premature wear of booster motors commutator. We then sometime get, intermittent booster motor starts.

I just had one with brake alarms (ABS was not activating), I found many issues. I worked one by one, until ultimately replacing the master. Each I corrected had a positive effect.

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[XAlent]

Thanks once again for your very comprehensive reply!

If no DTC indicating a bad wheel speed sensors. Your old ones are likely good. So was not the issue.

This was more a way to exclude one part of the system (out of frustration) that I could do quite quickly and easily. I agree that the old ones were probably still OK

So again I'll ask. Is this just dash lights, with actual ABS braking?

I wanted to disable the ABS system to understand whether it was in fact the ABS activating or something to do with the physical parts (rotors, pads, bearings etc) The ABS light came on as expected when the sensors were removed. At no time previous to this had the ABS light come on during normal driving even when the fault occurred. The fact that I felt the same issue occur when the ABS was disabled leads me to believe that perhaps it's something else causing it

Not likely a new parts issue.

I agree with this as well but you never know. I also agree that it's probably something I've done incorrectly when installing the rotors and bearings

Low speeds, are also low RPM. Alternator turns slower generates less power, especially if old weak. Voltage issues, can result in ABS lights, but would not activation of ABS braking. At least I've never heard of activation due to low voltage. Nor, can I think of reason it would.

The alternator is just over a year old and batteries are quite fresh and good as well however I haven't checked to see what voltage is at the pump during driving conditions and when the fault happens

Are you saying: ABS system, is braking (slowing vehicle) even after foot is off brake pedal? Not just ABS light on dash?

When the problem occurs and it feels as though ABS has activated, I'll lift the brake pedal completely and it will still shudder for a second or two afterwards. No ABS light

DBA rotors (disk) are very good disk and pads. I've never seen one with runout, out of spec. But, wheel hubs, transfer its runout to rotors disk. If wheel hub runout out of spec. Runout multiples, the further from center of axle. I've not seen runout so bad, it activates ABS (I've seen some very bad run out). But, If bad enough, at say just one wheel. Like FR. I suppose it could result in that pad and disk, running hotter than others. You'd likely see more brake dust at that wheel.

I'll check runout when I have another play this weekend

So to saying:"no lock up". Are you saying no wheel is being braked. It's just dash light coming on?
Or
Are you saying; ABS is braking (slowing vehicle). You hear the crunching sound of activation, and vehicle perhaps pull to one side or the other. Even though all wheels, were turning the same speed.?

What I mean is that the braking effort that I'm applying wouldn't be nearly enough to have a wheel lock up and cause activation of ABS. I understand ABS doesn't necessarily need to see complete lock up to activate, but the braking effort I'm applying should not in any way require ABS to activate.
So I'm braking, the vehicle is slowing, then I hear the crunching sound but it doesn't pull to one side even though I'm seeing more brake dust on RHF wheel. I'll lift the pedal, the crunching will cease within a second or two, then reapply pedal and it will brake normally

Tone ring needs to be in good condition. Wheel bearing tight, so that wheel speed sensors is not trying to read a tone ring that's wobbling. Oil seal, in correct, with flat side out

I've checked all of these to be correct on the front and cleaned grease from sensor rings, checked for cracks. I've checked that bearings and rings are seated correctly with no gaps.

Did you properly install the OEM outer shims in front calipers and the fitting clips? Many do not when using aftermarket pads.

I will recheck these.
Just looking at images now I'm fairly certain that I don't have the 'fitting clips' installed and I don't recall there being two shims on each side of each pad
Regardless I've just ordered a new shim kit and fitting clip kit

Would there be a chance that lack of correct shim kit could see the pad wiggle enough to grab at the disc and cause an ABS like feeling?

I'll recheck everything again when the shim kit arrives and pay close attention to the FSM drawings regarding pad installations.

If I understand correctly. This whole issue only began after you serviced wheel bearings and brakes (new DBA's). You then R&R some wheel speed sensors, due to ABS issue.

So it is more than likely, a procedural error during R&R. Not one of the part installed bad.

Yes I agree more likely my fault than failing master or ABS system. It's just too coincidental

Thanks for your reply once again, it's given me more to think about and areas to address
I'll let you know how I get on

 

[2001LC]

Tell me, what you "feel","hear" and how vehicle is behaving, while brake from 30 MPH? Without using words like, ABS. Be descriptive, like speaking to a 5 year old.

 

[XAlent]

So when slowing down, it doesn't happen instantly or every time. Around I'd say 15-20mph you can hear a muffled bang bang bang and feel the shudder through the steering wheel. It's loud enough and apparent enough that my boy can hear it from the backseat. I always release the brake pedal when I feel it, then reapply. After releasing, it usually continues for a couple more bangs. I haven't felt it occur when I reapply the brakes. The feeling and sound is identical to if I am on an unsealed road and deliberately apply the brakes hard enough to actuate the ABS (sorry ) I'll try to see if I can get a video of it occurring this weekend

I checked front left side last night
Has the outer shim fitted but not the inner one. The pads have their own plate glued to them but you can see in the photo how they have shifted. Not sure what has caused this. No fitting clips installed and there were none when the old pads were removed
Also photo of the FL disc

 

[2001LC]

So when slowing down, it doesn't happen instantly or every time. Around I'd say 15-20mph you can hear a muffled bang bang bang and feel the shudder through the steering wheel. It's loud enough and apparent enough that my boy can hear it from the backseat. I always release the brake pedal when I feel it, then reapply. After releasing, it usually continues for a couple more bangs. I haven't felt it occur when I reapply the brakes. The feeling and sound is identical to if I am on an unsealed road and deliberately apply the brakes hard enough to actuate the ABS (sorry ) I'll try to see if I can get a video of it occurring this weekend

Okay. So it does "sound" like ABS activating. Which could be due to install issue, resulting in a brake pad grabbing disk. This may then activate ABS. But if so, you should see dash lights when ABS activated. So do check (IG key on self test) dash lights.
If dash lights working as should. ABS alarms work as should. Then it may be a pad grabbing disk, without ABS activation.

Personally ABS sound to me is crunch crunch crunch. Is how I describe. But thats me!
I would also expect the feel (light jerking) of ABS braking? Did you also feel or just hear?

I one case, I did have ABS activate and lock on one rear caliper. It was a bad ABS unit (black box on side of master), damaged from bad fluid.

Sounds can fool use:
It can also be a transmission issue. So do check level.
It can also be engine misfire issue.

Take picture as you pull your brakes apart and post them. Maybe I'll spot something.

I checked front left side last night
Has the outer shim fitted but not the inner one. The pads have their own plate glued to them but you can see in the photo how they have shifted. Not sure what has caused this. No fitting clips installed and there were none when the old pads were removed

OEM inner shims are different. They're not glued, and have 4 clips. Fitting clips, work to hold sims sung again pad. With them pads may chatter. This could result in, movement of those aftermarket shims.

Also photo of the FL disc

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