Brake Actuator failure

[dgmorr]

Hey guys,

Initial symptoms point to a failed brake actuator unit - dash lit up, constant alarm, no stopping power.

Has anyone used one of the ebay units from China?
ABS Brake Pump Master Cylinder Booster Actuator For Toyota 4Runner GX470 A930444 | eBay


Do I need any special tools to replace this or is it just like replacing any other master cylinder? Saw a mention of a scan tool, does gravity bleeding work? Are all the 2003-2005 models cross-compatible whether V8 or V6?

Thanks

 

[AuSeeker]

Hey guys,

Initial symptoms point to a failed brake actuator unit - dash lit up, constant alarm, no stopping power.

Has anyone used one of the ebay units from China?
ABS Brake Pump Master Cylinder Booster Actuator For Toyota 4Runner GX470 A930444 | eBay


Do I need any special tools to replace this or is it just like replacing any other master cylinder? Saw a mention of a scan tool, does gravity bleeding work? Are all the 2003-2005 models cross-compatible whether V8 or V6?

Thanks

Those are "used" units, don't know if I would buy it being it is from China, if it doesn't work it would be hard to return it wihtin the 30 return policy if at all and you have to pay shipping.

You can find used units from USA savage yards on eBay with varying warranties for the same price or even less.

Do you hear the electric motor running when you depress the brake pedal?

These master cylinders don't fail that often and when they do the part that most often fails is the electric motor and usually it's only the brushes sticking, if you can take off the motor, take it apart and clean up the brushes and brush holders it most often fixes the problem.

You can also find a new OEM motor on eBay for around $500+/-

 

[dgmorr]

Those are "used" units, don't know if I would buy it being it is from China, if it doesn't work it would be hard to return it wihtin the 30 return policy if at all and you have to pay shipping.

You can find used units from USA savage yards on eBay with varying warranties for the same price or even less.

These master cylinders don't fail that often and when they do the part that most often fails is the electric motor and usually it's only the brushes sticking, if you can take off the motor, take it apart and clean up the brushes and brush holders it most often fixes the problem.

You can also find a new OEM motor on eBay for around $500+/-

Thanks.

It may just be the motor, I don't hear it come on like usual when I turn the key to the on position. Just happened this evening so I'm looking on ebay. I'll have to call a few yards tomorrow.

Do I have to stick to a 2003-2005 unit from a V6 only?

 

[AuSeeker]

Thanks.

It may just be the motor, I don't hear it come on like usual when I turn the key to the on position. Just happened this evening so I'm looking on ebay. I'll have to call a few yards tomorrow.

Do I have to stick to a 2003-2005 unit from a V6 only?

No difference for a V8 vs. V6, but only 2003, 2004 and early 2005, I think after 9/2004 build date (look on door jamb sticker) they changed the 2005 units

The motor should come on when you depress the bake pedal on intial startup and then about every 3rd time you depress the pedal.

 

[AuSeeker]

Also if you find one from a savage yard, try and find out the mileage from the vehicle it came off of, of course the lower the mileage the better.

 

[AuSeeker]

If you have to replace the whole unit here's a remanufactured unit for just under $800, free shipping w/ 1 year warranty and they will give you $200 back for your old unit.

(Also notice the "thru 9/2004" build date for the 2005 model, I think it's when they changed the design on these units)

http://www.ebay.com/itm/ABS-PUMP-BR...49-/252289738081?_trksid=p2141725.m3641.l6368

 

[dgmorr]

Yup, t doesn't turn on like it should. I may have some other issue as I'm noticing I can lock my driver door while its open - it was never possible for me before but could be toto silly unrelated.

Thanks for the info and link, that one didn't pop up in my search. Do I need to use a a special scan tool to bleed the unit?

 

[BlackWorksInc]

I do believe you still need a scantool (it needs to be either a TIS Techstream or at the very least Toyota ABS compliant) to properly bleed the ABS Solenoid Pack. But replacing it is pretty much like any other master cylinder. It's just got more lines and wires going to it and it weighs a hell of a lot more.

It shouldn't matter if it's a V6 or V8 for the assembly (but 2WD vs. 4WD does matter) because on the '03~'04 there's a separate Skid Control ECU. I could be wrong on that as it has been a while since I have had to replace one/order the parts.

I would use a website like Partsouq.com and punch in your VIN and get the part number you're looking for. They do also have a good price on brand new units if you want to go that route.

 

[AuSeeker]

Yup, t doesn't turn on like it should. I may have some other issue as I'm noticing I can lock my driver door while its open - it was never possible for me before but could be toto silly unrelated.

Thanks for the info and link, that one didn't pop up in my search. Do I need to use a a special scan tool to bleed the unit?

They say yes, but there are topics on the forum that shows it can be done without a scan tool, just do a search for bleeding brakes and you should find the topics, the best one it seems, tells you to turn the key on and depress the brake pedal about 40 times to relieve the pressure from the pump and goes on with other inportant details to get it done properly.

Also I edited 2 of my above posts to mention when they changed the design of these MC units during the 2005 production runs...."Also notice the "thru 9/2004" build date for the 2005 model, I think it's when they changed the design on these units", so not all 2005 models have the same units.

 

[BlackWorksInc]

They say yes, but there are topics on the forum that shows it can be done without a scan tool, just do a search for bleeding brakes and you should find the topics, the best one it seems, tells you to turn the key on and depress the brake pedal about 40 times to relieve the pressure from the pump and goes on with other inportant details to get it done properly.

Also I edited 2 of my above posts to mention when they changed the design of these MC units during the 2005 production runs...."Also notice the "thru 9/2004" build date for the 2005 model, I think it's when they changed the design on these units", so not all 2005 models have the same units.

Should be 40 times before turning on the key if I remember the FSM correctly, the purpose of that is to depressurize the accumulator pump (it's also the first step when you're replacing this to make sure the pressure is low.)

I don't recall if any of the "manual" methods account for the solenoid pack being bled or nor though. I haven't looked at some of those threads in a while.

 

[AuSeeker]

Thanks for the clarification, I have CRS most of the time(Can't Rember $hit) so that why I told him to do the search, so he gets it from the original posts.

 

[dgmorr]

Thanks for all the info guys. I'll take a look under the hood in the morning and make an order. Just wish it was the rear bumper that failed so I can just replace it with a swingout

Actually one last question for now. Is there a fuse for the unit I should be checking first? There is a relay that does activate for about the same time the pump would have run on initial power-on

 

[AuSeeker]

There's most likely fuse/s for the unit but I'm not positive, look in your owner's manual and you will know for sure, all fuses and what they're for are in there.

 

[dgmorr]

I'm gonna remove the actuator this weekend. Poked around for a bit. Do I have to remove the ECU looking device that is right by the brake pedal?

I'll see if I can take it apart to see if the electric motor is what has failed and get a quote on refurbishing the motor if the price is reasonable. If not I'll be ordering the refurb part off ebay.

 

[earthrealm]

Thanks for all the info guys. I'll take a look under the hood in the morning and make an order. Just wish it was the rear bumper that failed so I can just replace it with a swingout

Actually one last question for now. Is there a fuse for the unit I should be checking first? There is a relay that does activate for about the same time the pump would have run on initial power-on

yup, there is a 40amp fuse that controls it, when i had the issue, the bad motor took out the fuse, so when i dropped in the used unit i bought, it refused to work, the first mechanic refused to install the unit, after plugging in the cables and the unit didnt power on offline, said the unit i bought is defective.

i went to another mechanic who apparently didnt know much, after installing it, it refused to work. he was stumped!.
then i had a brain wave -- swapped the 40amp fuse with another in the engine bay, and the abs assy roared to life!

 

[dgmorr]

I was able to get the motor to run for about 3 second bursts if I hammered on the casing. This is a good sign to me, as I know it's probably the motor that has failed.

So spent about 15 minutes to figure out which universal joints and extension to piece together, 5 minutes of actual labor. Looks like the commutator coating failed for me, I was hoping it was just jammed brushes. I have about 2/3 left on the brushes based on spring compression.

The motor assembly is filled with abrasive dust.

I'm gonna order the refurb assembly as I don't feel like tinkering with this unit to have it restored.

 

[BlackWorksInc]

I don't recall commutators having coatings (beyond copper-oxide I suppose?), it looks like one or more commutator bars have been glazed perhaps too much current draw on the windings?

 

[earthrealm]

yeah, mine worked for about 2weeks more with some soft taps on the motor assy.
afterwards, the soft taps didnt make it work anymore.
i didnt bother opening it, will most def try someday soon

 

[dgmorr]

I don't recall commutators having coatings (beyond copper-oxide I suppose?), it looks like one or more commutator bars have been glazed perhaps too much current draw on the windings?

You may be right. I thought I read somewhere that this is just a copper plating and once worn off, will no longer work.

 

[AuSeeker]

You may be right. I thought I read somewhere that this is just a copper plating and once worn off, will no longer work.

On quality electrical motors the commutors bars are usually a solid piece so they can wear and still function for a long life, unless one of the bars has come loose, disconnected from the armature wiring, or shorted out with the bar/s next to it, they should work as designed, if the commutor doesn't have excessive wear it can also be turn on a lathe/mill to even it out/true it up.

The brushes could be binding in their holders/guides from the wear debris buildup within the motor housing, which a good cleaning and light sanding would solve.

The only other problems stopping the motor from working would be wiring shorting out in the windings and or bad bushings/bearings.