“Total” brake failure yesterday... accumulator pump motor CONFIRMED

[MissouriLC]

I experienced a “total” break failure in my ‘00 Cruiser yesterday. I’ve had the truck since January. During the first couple of weeks of ownership, I got the ABS/TRAC/Brake lights on the dash with the alarm... always on a cold morning first start. It would typically go away after 30 to 40 seconds. It did this maybe 8 to 10 time total and then stopped doing it for 8 months, until yesterday. I got the warning multiple times at start up, and then while driving in the afternoon, the lights and alarm came on and I lost most of my braking power. Having read the various threads on this, I knew what to expect. Luckily my office is only 10 minutes from home, and I was able to carefully drive home, using a combo a 2nd and 1st gear engine braking, the hand brake, and HARD pressure on the brake pedal.

I am fairly confident that the issue is a failed accumulator pump motor. While diagnosing last night, here’s what I was able to determine:

1. With the key in the ON position, “ABSMTR1” and “ABSMTR2” relays in the main fuse box open and close every 10 seconds or so.
2. The pump motor makes an electric, buzzing or humming sounds, but placing my hand under the MC on the pump and motor, I feel no vibration from the pump. (Edit: This may not have been the pump making this sound... I don't know.)
3. I tapped the pump repeatedly with a wrench, and it MIGHT have run for a second or so (I heard a momentary, loud vibration or grinding sound), but that was it. (Edit: In hindsight, I do not think that it ever ran.)
4. No pressure is being built in the accumulator. The fluid in the reservoir is up at the FULL line and does not change (does not drop to indicate fluid being pumped into the accumulator).

It sounds to me like the pump is stalled and not spinning. Occam’s razor would suggest that the motor itself is shot. I suppose it’s possible that the pump itself is clogged or seized. The system has no leaks, no double-pump pedal symptoms, and seemed to be working perfectly until yesterday.

(UPDATE 1)
Thanks, 2001LC, for the diagnostics advice. Here’s what I was able to accomplish last night:

• Before for proceeding with any further disassembly, I conducted the diagnostics that 200LC referenced form the FSM. First is to apply 12 v to the specified pins on the ABS solenoid block connectors. There are two large blades/pins in the center of the upper-left connector—one on top of the other. Connect the top blade to positive, the bottom blade to negative, and the motor should spin. I did this, and the motor DID NOT spin.

• Next step, per the FSM, is the check the resistance of the circuit through the ABS block and the motor. On the same connector, there are three small pins to the left of the aforementioned power pins, arranged vertically. You measure the resistance between the middle pin and the bottom pin. It should measure between 30 and 36 ohms. Mine measured 33.0 ohms. Perfect!
• Next step, per the FSM, is to troubleshoot the ABS/VSC light circuit in the ECU harness. I opted not to do this, because the lights are clearly not false alarms. Results from the first two tests suggested to me that the ABS solenoid block circuit is good, and the motor has a good connection, so the problem must be internal to the motor. Time to pull the MC assembly
  (Note: I followed Skiddoo’s excellent how-to on the rebuilding the MC to guide me through removing this.)
• Step 1: Disassemble the driver’s side lower dash under the steering wheel. You will have to:
  • Remove the dead pedal (mine pulled straight out easily), pry up the front end of the plastic door sill trim, and pop off the kick panel (plastic clips only, no screws.
  • Pull the weatherstripping away from the front lower half of the door jamb.
  • Carefully pop off the black plastic trim strip below the instrument cluster (clips only).
  • Remove one (1) phillips screw from the lower left side of the dash trim panel, below the hood and gas filler door release levers.
  • Remove two (2) screws each from the hood and gas filler door release levers. These are hidden when the levers are in their “neutral” position. Carefully push the levers through the trim panel to the inside.
  • Working around the perimeter, carefully pry the trim panel off. There are an number of plastic clips, all of which release easily.
  • Remove the metal panel behind the plastic trim piece with four (4) 10mm bolts.
  • The ABS computer is mounted directly left of the steering column. Remove two (2) 10mm bolts, unhook the electrical connectors, and set the ABS computer aside (you’ll need a long extension and perhaps a U-joint to access these bolts.

• Step 2: Unbolt the MC from inside the firewall. There are four (4) bolts, located in a rectangle around the MC plunger rod (connected to the top of the brake pedal). I did not remove the “crotch vent” HVAC duct, which made the bolts slightly harder to access, but still very doable. You need a 12mm deep-well socket.

• Step 3: Remove the cotter pin and clevis pin connecting the brake pedal to the MC plunger rod clevis.
• Step 4: Move the charcoal canister in the engine bay. There is one (1) 10mm bolt holding the charcoal canister to the bracket that mounts it to the inner fender. It is located near the top, front edge of the charcoal canister. On the lower, front edge of the canister, toward the engine, there is a rubber hose with no hose clamp. Carefully remove this hose. Unhook the two (2) electrical connectors on top of the canister, and the pull the canister UP and out of the bracket. Mine required a good, hard pull, so much so that I thought I might have missed a bolt. Once out of the bracket, carefully move the charcoal canister to the open space between the fuse box and the engine cover.

• Step 5: I not already done, unhook all the electrical connectors from the MC assembly. There are three (3) on the ABS solenoid block (facing the inner fender); one (1) up high near the reservoir (fluid level sensor); and one (1) below the fluid level sensor (pressure sensor).
• Step 6: Unscrew the flare nuts for the four (4) brake lines. Place some rags or paper towels to catch drips. Use a 10mm flare nut wrench. Mine were very easy to loosen (torqued to only 10 lb-ft or so). I would say that only about 1/4 oz of fluid leaked out.
• Step 7: This was the hardest part—wrestling the MC assembly out of the car. You need to pull it out and rotate it up and to the left (toward the left fender). It will want to get caught on the wiring, the detached brake lines, basically everything. Plus, the MC assembly is heavier than I anticipated, and it has to come pretty far forward for the plunger rod to clear the firewall. Just work back and forth, constantly moving the brake lines out of the way, and it will eventually come out.

(Continued Below...)

 

[2001LC]

First never ignore a brake warning light or buzzer.

How's wire under the ABS to boost look?
I use a mirror to inspect wires at bottom of ABS unit..
These are bad.

To see if motor is running: Follow direction on top of reservoir for topping. i.e. IG key off, pump pedal 40 times to evacuation accumulator. Then when you turn key on after the accumulator evacuation procedure (topping procedure), motor should run for 30 to 40 seconds which is spec range.

If does not run. Jump with 12V battery at wire block on ABS unit (black box attached to side of master) The FSM has this procedure and which leads to jump. If motor still will not run, test by jumping directly on motor. Your checking if current is getting through the ABS unit. Then testing at motor to see if motor runs by direct jump.

(Sorry, I can post the FSM page at this time)

Notes:
1) The leads are very depended on positive and negative jump from battery being one way only. Do not reverse.
2) I've had bad motor appear good. The commutator may have a dead spot. If brushes on good spot motor runs, then land on bad spot and does not.

 

[e9999]

I'd suggest checking the big thread in the stickies. Although, admittedly, that one is also mostly 2001LC , so you already have the short version....

 

[Magikarp]

Most likely booster motor issue . Check out this thread posted by superdawg: Source for rebuilt booster pump on master cylinder

 

[MissouriLC]

(Continued from first post...)
At this point, I carefully dumped the old brake fluid from the reservoir into a bucket on my bench, and then set the MC assembly upside down in a clean pan. I placed some clear rags over the brake line ports to keep dirt out. I also laid some clean rags over the disconnected brake lines in the engine compartment.
Time to remove the motor.

• Step 8: There is a wire harness of two (2) wires connecting the pump motor to the ABS solenoid block. There is a rubber boot covering both connections. Peel this back off the ABS block side, and check for corrosion. Mine were very clean. Remove two (2) phillips head screws holding the two ring terminals. The position of the wires—red and blue—is critical, but the rubber boot is also directional, and it really only fits back on one way.

• Step 9: The pump housing is connected to the pressure accumulator (which is the vertical, beer can looking thing next to the fluid reservoir. The motor is bolted to the pump housing with two (2) allen bolts. I think these were 3.5mm.
• Step 10: Once the bolts are removed, separate the motor from the pump housing. Mine was firmly stuck, and required a few light taps with a brass drift to get it unstuck. Once it starts to move, use a screwdriver to carefully pry the motor off. There is a thin paper gasket between the motor and pump. I understand this part is not available separately, so I carefully separated mine from the motor housing with a razor blade. There’s a lovejoy coupler between the pump shaft and the motor shaft. Be sure to remove this and set it aside so you don’t lose it.

Now that the motor was out, I wanted to jumper it directly to see if it ran. Hooked it up to my battery and… IT SPUN! (What does this mean???) I started and stopped in 20 times, and 5 of those times, it wouldn’t restart without a good shake. This is suggesting that the commutator is worn. So, I decided to break open the housing a have a look.

(Edit: At this point, I also rotated the pump shaft with my fingers to feel for any resistance or binding. The pump shaft turned smoothly, so I am hopeful that there is no issue/blockage with the pump.)

• Step 11: There are two (2) more allen bolts holding the motor can to the base plate. There are the same size (but not interchangeable with) the bolts holding the motor to the pump housing. Remove these, and then carefully pry the can away from the base plate.

When you open the housing, you will see a coated metal gasket between the can and base plate. I carefully removed and set this aside for possible future use.

There is also a thin wave washer that sits between the upper rotor bearing and the housing can. This will probably fall out and stick to one of the stator magnets. Find it and set aside for possible future use.

Once opened, I saw that the brushes are about halfway worn down, and almost half of the circumference of the commutator was completely worn through the copper down to the plastic core.

So, I reassembled the motor and took it to a forklift repair shop in St. Louis today to see if they can rebuild it. The owner is pretty confident that he can source the necessary parts and turn around the rebuild in a few days (apparently, this is a very similar motor to the power steering motor that Japanese forklifts use). Eurton Electric is always a back-up, but I will see if I can get it rebuilt locally first.

While the MC assembly is out, I will probably replace the three rubber grommets between the fluid reservoir and the MC as a preventative measure. I may also rebuild the MC, but I wasn’t having any of the symptoms typical to an MC rebuild, so I am thinker better leave well enough alone (unless there is a good reason to go ahead and rebuild).

Thanks again for all the advice so far! I will continue to post updates as they come.

 

[katit]

So, I reassembled the motor and took it to a forklift repair shop in St. Louis today to see if they can rebuild it. The owner is pretty confident that he can source the necessary parts and turn around the rebuild in a few days (apparently, this is a very similar motor to the power steering motor that Japanese forklifts use). Eurton Electric is always a back-up, but I will see if I can get it rebuilt locally first.

Pretty cool. Can you post/PM info on this shop? And if they do fix, what it cost?

 

[kruisinkid]

the million dollar question: how many miles are on your truck?

 

[2001LC]

Typically I see brushes more worn and commutator okay, when wires are not corroded. Interesting!

I'm real interested if this "shop in St. Louis" can source and R&R the commutator. A local re-builder I went to, could not.

When I go to point I've pulled the master. For $50. I like to go ahead and get a master plunger kit. Just adds 30 mins to the job.

BTW. For future reference. I've not found it necessary to pull dash apart. At least not when working on non VGRS systems. I've not pulled a master from any 03-07LX so not sure with the VGRS.

Edit 10/31/24: No need to pull apart any 100 series dash, when R&R brake master. The only part I move, out of the way. Is the ABS CPU hung on two studs held on by 10mm nuts, just left of brake pedal assembly. This gives better access to the masters left side mounting studs' two 12mm nuts.

 

[gil12]

+1 on doing the master cylinder. I was impressed on the quality of the part for the $50 spent.

 

[MissouriLC]

the million dollar question: how many miles are on your truck?

242K... sorry, should have put that in the first post!

As well, I think a lot of the miles have been city driving, and I know the P/O pulled a small trailer with it often. I suspect that the pump was working overtime with a lot of stop and go driving.

 

[katit]

242K... sorry, should have put that in the first post!

As well, I think a lot of the miles have been city driving, and I know the P/O pulled a small trailer with it often. I suspect that the pump was working overtime with a lot of stop and go driving.

Yes, I think it's either lot of stop-go or something with a system (pressure?) that causes pump run a lot. Wouldn't it indicate wear on pump as well? I'm just guessing here...

 

[MissouriLC]

Typically I see brushes more worn and commutator okay, when wires are not corroded. Interesting!

I'm real interested if this "shop in St. Louis" can source and R&R the commutator. A local re-builder I went to, could not.

When I go to point I've pulled the master. For $50. I like to go ahead and get a master plunger kit. Just adds 30 mins to the job.

BTW. For future reference. I've not found it necessary to pull dash apart. At least not when working on non VGRS systems. I've not pulled a master from any 03-07LX so not sure with the VGRS.

That's interesting... I've been doing some research myself the last few days on commutator wear. I found the article linked to below:

Maintaining DC Motors

It states:

Grooving: Unlike threading, grooves tend to smoothly wear to the width of the brushes, and commutator material is worn away rather than transferred to the brushes. Although grooving is usually due to abrasive dust in the environment, it can also be caused by a brush grade that's too abrasive. As grooving progresses, the sloped walls pinch the brushes, diverting spring tension from the brush face. This increases electrical resistance, generating more heat at the brushes and commutator. Left unchecked, grooving may lead to a “flashover,” or arcing between brush holders, that can seriously damage the brush holders, the commutator, or both. At the first sign of grooving, check for and eliminate airborne abrasive dust. Corrective actions include adding filters or ducting that moves clean air from another location. In either case, it's critical to maintain adequate airflow, because if grooving progresses too far, the only solution is to replace the commutator, which requires an armature rewind.

So, it's clear that once grooving starts, it is precipitated at a faster rate as the electrical resistance between the brushes and the commutator increases (in fact, I understand that this causes electron erosion of the commutator--the current literally eats the copper away). But what starts it in the first place? A brush that's too abrasive? Not likely. Dust? The inside of my motor had a lot of carbon and copper dust as a by-product of the grooving. However, did that start the problem?

The article further states:

Current density and brush grade: Each carbon brush grade is designed to carry a specific current. High-current density increases the operating temperature of carbon brushes. Current density that's too low causes rapid brush wear. In extreme cases, brushes can dust, or wear out, in days. To determine current density, measure the cross-sectional area of the brush surface. Think of the brushes as a group of series-parallel conductors. Since half of them constitute a parallel path for the armature current, those brushes share the total armature current.

"Current density that's too low causes rapid brush wear"... Logic would suggest that a heavily-corroded power wire would have increased electrical resistance, resulting in lower current to the brushes. That would suggest the exact OPPOSITE of what you've observed--rapid brush wear. Of course, in a mostly-sealed motor assembly like that, rapid brush wear could create dust which would precipitate grooving... maybe that's the answer?

I also read that motors that operate under light loads tend to groove commutators... but that shouldn't apply in this case. Pumping fluid, the load should be pretty constant.

Out of curiosity, with the units you've collected and autopsied, have you tracked the mileage? How does the mileage correlate to the power wire condition and commutator/brush wear? It would be interesting just to know for purposes of diagnosis... does a quickly-wearing commutator indicate something else out of spec (other than the condition of the power wire)?

Of course, these motors seem to last in the neighborhood of 20 years and 250K miles at worst... I estimate with my driving style and mileage, that motor is probably running 10 to 12 minutes per day. That's about 60 to 70 HOURS per year, or about 1,200 to 1,400 hours over 19 years... in an environment that ranges from 10 deg F to 180 deg F with vibration, dust, etc. In perspective, that's a pretty damn durable motor.

 

[MissouriLC]

Yes, I think it's either lot of stop-go or something with a system (pressure?) that causes pump run a lot. Wouldn't it indicate wear on pump as well? I'm just guessing here...

I would guess my pump kicks on for about 4 seconds every other time I stop, on average and based on when I hear it. Plus another 20 to 30 seconds on a cold start, depending on how long the vehicle has been sitting. Since I do 70% city driving, my pump is easily running 10 minutes throughout the day, on average. If I was driving the same time duration on the highway, it might run only 2 or 3 minutes per day.

Pump wear would, I think be limited to impeller bearings and seals. I would guess if the pump is making noise, it's probably not suffering undo wear. However, I have hear of symptoms where the pump shrieks or sounds like a vacuum cleaner when it kicks on. That would definitely indicate pump wear.

 

[2001LC]

That's interesting... I've been doing some research myself the last few days on commutator wear. I found the article linked to below:

Maintaining DC Motors

It states:



So, it's clear that once grooving starts, it is precipitated at a faster rate as the electrical resistance between the brushes and the commutator increases (in fact, I understand that this causes electron erosion of the commutator--the current literally eats the copper away). But what starts it in the first place? A brush that's too abrasive? Not likely. Dust? The inside of my motor had a lot of carbon and copper dust as a by-product of the grooving. However, did that start the problem?

The article further states:



"Current density that's too low causes rapid brush wear"... Logic would suggest that a heavily-corroded power wire would have increased electrical resistance, resulting in lower current to the brushes. That would suggest the exact OPPOSITE of what you've observed--rapid brush wear. Of course, in a mostly-sealed motor assembly like that, rapid brush wear could create dust which would precipitate grooving... maybe that's the answer?

I also read that motors that operate under light loads tend to groove commutators... but that shouldn't apply in this case. Pumping fluid, the load should be pretty constant.

Out of curiosity, with the units you've collected and autopsied, have you tracked the mileage? How does the mileage correlate to the power wire condition and commutator/brush wear? It would be interesting just to know for purposes of diagnosis... does a quickly-wearing commutator indicate something else out of spec (other than the condition of the power wire)?

Of course, these motors seem to last in the neighborhood of 20 years and 250K miles at worst... I estimate with my driving style and mileage, that motor is probably running 10 to 12 minutes per day. That's about 60 to 70 HOURS per year, or about 1,200 to 1,400 hours over 19 years... in an environment that ranges from 10 deg F to 180 deg F with vibration, dust, etc. In perspective, that's a pretty damn durable motor.

Good research my friend. KUDOS!

I do see at least some grooving in most if not all motors I've pulled apart. I'll watch more closely now. But that's a bit of a chicken and egg story. Wear create dust.... Dust creates wear I've pulled motors with good wire at 250K miles mark and commutator was fine and they all have dust in them. Dust enters from vent port and internal wear.

We can't easily inspect for dust in motor. But we can inspect the wires in a field inspection. This inspection is what I'm interested in. It is an earlier warning IMHO!

My thinking is, the increase in resistance due to corrosion on wires. This is reducing life of commutator which is solid copper. This is what I see 8 of 10 (your's took from 9-10) when wire corroded, commutator has excessive wear.

Excessive running does cause excessive heat which increases resistance also. But unless I've a vehicle all its life or know it's pump run time test (indicating pressure issue or not) were done frequently. I can't make any assessment on excessive run time. Only indicator if no history of run time test, is how many brake jobs or leaks, etc. Miles is poor indicator.

As you research this issue, also look into effects of increase resistance on copper. What you'll find is this does cause excessive wear of copper. It's one of the reason a handheld electric drills or shop vacs will have in the OM, limits on size and length of extension cord.

Currently if I see wires corroded, I advise replacing them as a PM. Than at same time I pulled motor apart and inspected.

The wire, nuts, and screws are non reusable anytime removed, per FSM! It gives no test for wire just not considered reusable. This is a big clue IMHO, that Toyota has always had concerns with resistance. This resistance may also effect internals of ABS unit.

I've and 00LX with over 350K miles now. Wires look good and no brake issue and run time good. So mileage is bad indicator. I will be pulling master one day, just to check in the motor.

 

[I Lean]

Good research my friend. KODOS!

Kodos caused the commutator wear?

Just kidding. This is an awesome thread, for something I kinda dread having to dig into at some point in the future.

 

[MissouriLC]

I'm real interested if this "shop in St. Louis" can source and R&R the commutator. A local re-builder I went to, could not.

Just got the call... he was able to source the correct lug-type commutator--and new brushes--which will arrive on Monday (Oct 21). Bearings are good, no need for replacement. He said they will rewind the armature, clean, and reassemble everything for $190 out the door bounce. Should be ready on Wednesday (Oct 23).

I feel a little bit funny posting the place on here w/o his permission because I am not sure he wants to potentially be flooded with this kind of work! But, I'll be happy to PM you if you are interested.

I've got new bleed screws, new bleed screw caps, new reservoir grommets, and an MC rebuild kit on order from McGeorge Toyota. Traveling for work next week, but hopefully I'll be able to get this buttoned up by next weekend.

 

[kruisinkid]

damn. thats amazing someone can (hopefully) reman these. thats several hundred cheaper than new. cant wait to hear if it works out. this is a huge score. you should link to this thread in the sticky thread.

 

[2001LC]

Sweet. Please do PM me. Sound like you found a good one.

Actually there are a lot of motor re-builders around. Most of these re builders are just throwing in brushes. Most don't replace commutator or rewind.

 

[Blake1]

My brakes look great but!!! here is mine .. what should I do .. 2001 at 150 k miles

Time for preventative maintenance . ??

 

[2001LC]

Edit 2024:

• Toyota reduce the price of booster assy w/masters (the whole Master). Dropping the price about $1K. It's a great deal. I just replace the whole master assy, these days. It's less labor, a one and done and the safest. Whereas one can replace or rebuild the motor, even other parts of master. To often we end up with master that has, a weak eternal seals. Resulting in excessively long run time. Then we're back to issues resulting heat and excessive wear of commutator.
• I've found "bad" brake fluid (mixing brands and or excessive moisture). Often results in longer run times of booster motor. Toyota has a warning in diagnostic section: Do not run motor longer than 2 minutes, while running test. These motors are designed to run often, but only for short duration. Running longer duration, reduce motor life.
• I use only Toyota brake fluid. I find the fluid stay better (less moisture) for longer. I've also found, run time of booster motor/pump, is reduced, with Toyota brake fluid.

Blake1: I would pull master and replace that wire assembly, screws & nuts. If you could please test resistance before removing, just wire after and then again after new installed and report it mud. Please PM if you don't see give you like when/if you do.

Be very careful drilling out the screws. Just take your time and start with small drill bit and work your way up. Just removing head of screws.