ABS Issue (1 Viewer)

[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...

forum.ih8mud.com

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