V8Man
Member
This worked for me. Turn the com in a lathe. I had two burnt areas the op looks to have three. A drill and Emory cloth works too. In the long ago poor times "rebuilt" lots of starters this way.
Brake Actuator failure
- Thread starter dgmorr
- Start date
This worked for me. Turn the com in a lathe. I had two burnt areas the op looks to have three. A drill and Emory cloth works too. In the long ago poor times "rebuilt" lots of starters this way.
Here's why I thought it may be a coating, very thin layers flaking off. I guess I could've just ordered a new motor instead of the entire assembly. All but two and a half bars have come off.
EDIT: spun it in my Dewalt "lathe" with some emery cloth and getting no copper. Pretty certain now that it's just a copper plating - or is that step above and below the brushes the original thickness and mine has worn down to the core?
EDIT: spun it in my Dewalt "lathe" with some emery cloth and getting no copper. Pretty certain now that it's just a copper plating - or is that step above and below the brushes the original thickness and mine has worn down to the core?
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AuSeeker
Elite Member
Here's why I thought it may be a coating, very thin layers flaking off. I guess I could've just ordered a new motor instead of the entire assembly. All but two and a half bars have come off.
EDIT: spun it in my Dewalt "lathe" with some emery cloth and getting no copper. Pretty certain now that it's just a copper plating - or is that step above and below the brushes the original thickness and mine has worn down to the core?
Your commutor blocks have indeed worn beyond repair and thus the stepdown you're seeing in the commutor bars, look at the photos in the linked topic below and you can see that Hawiian Hillbilly's commutor is worn similar to your's but it is not worn nearly as bad and has some life left thus allowing him to clean up the motor, brushes, commutor and gets his motor functioning again.
Also the second post from V8Man shows a similarly worn but serviceable commutor but also badly burned which he was able to use a lathe to cut it down a bit to get his back to working.
http://www.toyota-4runner.org/4th-gen-t4rs/225205-2003-v8-brake-booster-pump-diy-fix.html
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I swapped in my refurb unit and seems to be running in about 4-6 second bursts. The reservoir and mc are completely dry. Will I continue to get the alarm until there is some hydraulic pressure or is the alarm based on the pneumatic pressure. Won't get a chance to get some brake fluid until later tonight.
AuSeeker
Elite Member
I wouldn't recommend letting the motor run or depressing the brake pedal without having brake fluid in the system, it not design to run dry!!!
There is only hydraulic pressure involved with the system, no pneumatics involved at all, unless you have air in the system along with the brake fluid which in that case the system needs to be bled to rid the system of all air, the pump as well as the master cylinder piston both produces hydraulic pressure.
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OK good to know. Not sure why I said pneumatic :der: I'm gonna try and find time to gravity bleed the fronts tomorrow and pressure bleed the rears another day.
After doing a lot of Googlefu on the brake actuator, I just discovered that my Lexus LS also suffers from this potential achilles heel :nono: Only reason I got this over an E class was because of their similar brake controller issues as well, no lol.
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I have lately noticed I can hear the noise almost every time I press the brake pedal at a low speed, such as if I'm creeping through a drive thru. Should I be concerned if it is more often than every 3 times?
I have no loss of fluid and my brakes seem to be working fine. I have an extended warranty that is about to expire. I have contemplated taking the truck in to get checked out, but i saw another thread where mulitple dealers told a guy always hearing the noise is always normal, so not sure if its worth my time.
All fixed up and back on the road again. Just to clarify, Techstream and/or a dealer visit wasn't required for the bleed process.
The hardest part of the entire job is physically putting the new unit in place. Lining up the brake pedal bracket with 4 holes and the firewall 4 holes required quite a bit of wiggling. I ended up jamming a length of wood to hold the brake pedal assembly in place. I didn't really follow the FSM bleed steps and they didn't really make much sense to me. I think the main thing they're trying to accomplish in their process is to empty the accumulator.
I meant to make a video of the process but I forgot until I closed the last nipple.
Here are the steps I took
1) Press brake pedal about 50 times in short strokes - 1-1.5" with key off. You should eventually feel some resistance. Repeat as many times as required to get some resistance. This step may or may not be required. I just did it. Gravity bleeding should accomplish the same thing.
2) Bleed front calipers with your desired method, ignition off. I did a partial gravity bleed to fill my vinyl tubing, then once i had enough in the catch bottle, I made sure the tubing was snug around the nipple and proceeded to press the brake pedal to have it flow faster. Once the nipples are closed up, the pedal should feel like a rock. Keep an eye on reservoir level.
3) Put the vinyl tubing on the rear nipples. Turn ignition on, use a rod or have someone hold brake pedal down. I think enough pressure to activate the brake lights should be far enough. Open nipples. Wait for clear fluid and no more air bubbles, make sure to watch reservoir level. Close everything up.
4) Turn car off, then start it up. Drive away.
I didn't have to do a zero point calibration or fiddle with any other electronics. The pump did seem to run in 4 second intervals every 8 seconds for whatever reason. After several cycles everything cleared up. I did this all on my own with all the wheels still on. Pretty sure anyone with slightly above average mechanical aptitude can do the same.
Good luck
The hardest part of the entire job is physically putting the new unit in place. Lining up the brake pedal bracket with 4 holes and the firewall 4 holes required quite a bit of wiggling. I ended up jamming a length of wood to hold the brake pedal assembly in place. I didn't really follow the FSM bleed steps and they didn't really make much sense to me. I think the main thing they're trying to accomplish in their process is to empty the accumulator.
I meant to make a video of the process but I forgot until I closed the last nipple.
Here are the steps I took
1) Press brake pedal about 50 times in short strokes - 1-1.5" with key off. You should eventually feel some resistance. Repeat as many times as required to get some resistance. This step may or may not be required. I just did it. Gravity bleeding should accomplish the same thing.
2) Bleed front calipers with your desired method, ignition off. I did a partial gravity bleed to fill my vinyl tubing, then once i had enough in the catch bottle, I made sure the tubing was snug around the nipple and proceeded to press the brake pedal to have it flow faster. Once the nipples are closed up, the pedal should feel like a rock. Keep an eye on reservoir level.
3) Put the vinyl tubing on the rear nipples. Turn ignition on, use a rod or have someone hold brake pedal down. I think enough pressure to activate the brake lights should be far enough. Open nipples. Wait for clear fluid and no more air bubbles, make sure to watch reservoir level. Close everything up.
4) Turn car off, then start it up. Drive away.
I didn't have to do a zero point calibration or fiddle with any other electronics. The pump did seem to run in 4 second intervals every 8 seconds for whatever reason. After several cycles everything cleared up. I did this all on my own with all the wheels still on. Pretty sure anyone with slightly above average mechanical aptitude can do the same.
Good luck
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earthrealm
Senior Member
@bolded, my truck never does this..with key off, if i intend to do the 40-50 pedal thingy, my pedal goes flat/looses resistance after about 10pumps, previous MC assy behaved same way too.
could someone please confirm if this is a bad sign
It may also depend on numerous other factors like how much air in the lines etc. In my case I think it was from using any reserve pressure in the accumulator from initial key on. Without any assistance it should be harder, which you might not even feel.
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Very helpful thread !
This thread plus a couple of other ones was extremely helpful to me. I had the same failure, lights, buzzer as others on a 2004 4Runner. Towed to Toyota dealer & quote was $3510.00. I told them no & we picked it up on a trailer & brought it home. I tapped on the pump motor with a socket & it came back to life. Now I just need to figure out how to get the motor off without disturbing the hydraulic system. Thanks for all the good info.
This thread plus a couple of other ones was extremely helpful to me. I had the same failure, lights, buzzer as others on a 2004 4Runner. Towed to Toyota dealer & quote was $3510.00. I told them no & we picked it up on a trailer & brought it home. I tapped on the pump motor with a socket & it came back to life. Now I just need to figure out how to get the motor off without disturbing the hydraulic system. Thanks for all the good info.
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