[plcfcng]

Just replaced my alternator brushes a week ago and noticed how the stable voltage improved curb idle and lights being steady in brightness even at idle. I was thinking a reason to keep up on the electrical system is that pricey Master Cylinder I have. Low voltage is a reason for electric motor failure. The 4Runner I have had always gotten a little brighter when I accelerated off of curb idle but the charge light had not come on until recently.

Things to do to maintain electrical.

1. Keep Batt Terminals clean and tight 6 months to a year should be often enough. (I use Copper anti seize on cables )

2. Check Batt cables for corrosion replace as needed

3. Clean ground contact points with a bit of sand paper and a little of the Copper anti seize.

4. Keep drive belts at the proper tension.

5. A good idea to change your brushes on your alternator after about 180,000. (saw a posting brushes
last about 200,000) saw this the other day.

Not looking forward to when I have to buy that Master Cylinder

[tvpierce]

Is there a write-up on replacing the brushes?

[brillo_76]

Originally Posted by tvpierce

Is there a write-up on replacing the brushes?

A few threads exist on changing the alternator and starter brushes. I see them from time to time. A quick search should bring them up.

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[brillo_76]

Originally Posted by plcfcng

Just replaced my alternator brushes a week ago and noticed how the stable voltage improved curb idle and lights being steady in brightness even at idle. I was thinking a reason to keep up on the electrical system is that pricey Master Cylinder I have. Low voltage is a reason for electric motor failure. The 4Runner I have had always gotten a little brighter when I accelerated off of curb idle but the charge light had not come on until recently.

Things to do to maintain electrical.

1. Keep Batt Terminals clean and tight 6 months to a year should be often enough. (I use Copper anti seize on cables )

2. Check Batt cables for corrosion replace as needed

3. Clean ground contact points with a bit of sand paper and a little of the Copper anti seize.

4. Keep drive belts at the proper tension.

5. A good idea to change your brushes on your alternator after about 180,000. (saw a posting brushes
last about 200,000) saw this the other day.

Not looking forward to when I have to buy that Master Cylinder

Excellent write up and 100% accurate as low voltage is the major reason for electrical motor failure. Great Job..

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[Jidaran]

thanks for the reminder. i'm about to hit 200k and i don't have any repair history that shows the brushes have been done. definitely on the list for this spring.

[rightyouareken]

FWIW, if your motor does go, you don't actually need to replace the whole master cylinder/ABS module assembly if you don't want to. The pump, motor, and accumulator are available as a unit for about $750 new:

1998-2007 Toyota Brake Booster 47070-60010 | Boch Toyota South

Unfortunately, when my master cylinder kicked the bucket, the failure was with a pressure switch internal to the ABS module, so I ended up replacing the whole unit. That was a bit of a bitter pill, but it's nice to know it should be good for another ~170k miles.

[brillo_76]

Originally Posted by rightyouareken

FWIW, if your motor does go, you don't actually need to replace the whole master cylinder/ABS module assembly if you don't want to. The pump, motor, and accumulator are available as a unit for about $750 new:



1998-2007 Toyota Brake Booster 47070-60010 | Boch Toyota South



Unfortunately, when my master cylinder kicked the bucket, the failure was with a pressure switch internal to the ABS module, so I ended up replacing the whole unit. That was a bit of a bitter pill, but it's nice to know it should be good for another ~170k miles.

Good to see they are still available as some of the 3rd parts are being discontinued.

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[plcfcng]

Originally Posted by rightyouareken

FWIW, if your motor does go, you don't actually need to replace the whole master cylinder/ABS module assembly if you don't want to. The pump, motor, and accumulator are available as a unit for about $750 new:

1998-2007 Toyota Brake Booster 47070-60010 | Boch Toyota South

Unfortunately, when my master cylinder kicked the bucket, the failure was with a pressure switch internal to the ABS module, so I ended up replacing the whole unit. That was a bit of a bitter pill, but it's nice to know it should be good for another ~170k miles.

There is a kit rebuild kit for the part of the master cylinder that contacts the brake fluid. I have seen on ebay some units that have been rebuilt I don't know of the quality. Some owners of 01 and 02 will look for some one parting one out and just keep it on hand in case they have a failure ( this doesn't help when your 200 miles from home but from what I have heard the failure happens typically with some warning like extended run time on the pump that you hear when first turn the key on.)

Rebuilding the motor i have not seen not saying there isn't something out there. If some one is putting them on Ebay then some one has worked something out.

[rightyouareken]

Originally Posted by plcfcng

There is a kit rebuild kit for the part of the master cylinder that contacts the brake fluid. I have seen on ebay some units that have been rebuilt I don't know of the quality. Some owners of 01 and 02 will look for some one parting one out and just keep it on hand in case they have a failure ( this doesn't help when your 200 miles from home but from what I have heard the failure happens typically with some warning like extended run time on the pump that you hear when first turn the key on.)

Rebuilding the motor i have not seen not saying there isn't something out there. If some one is putting them on Ebay then some one has worked something out.

Yeah, some have tried rebuilding their motors with varying levels of success. FWIW, our brake systems are very similar to 100 series Landcruiers, FJ Cruisers, and even the 4th and 5th gen 4runners and new Tacomas. They all have the same motor driven pump/accumulator style brake boosters. Maybe they sorted some of the problems since our first gen units, but who knows.

There is lots of info on the forums over at ih8mud.com which is the Landcruiser forum.

From what I've seen, there are several different failure modes with these systems:

1) Brake pedal to the floor followed by loud buzzers and lights in the cabin. This is typically solved by rebuilding the master cylinder hydraulic piston like any normal car master cylinder rebuild kit. There is a ~$50 kit from Toyota for the rebuild.

2) Hard pedal/loss of brake boost accompanied by loud buzzers and lights in the cabin. This would be booster pump motor/pump/accumulator failure, where the power assist is lost. This should be able to be resolved by replacing the motor/pump/accumulator for ~$750 for a new subassembly form Toyota.

3) "Dying seagull screeching" when starting the truck in the morning. This was my symptom, and seems to be the hardest to pin down, and may have various causes and solutions. This seems to be some type of hydraulic cavitation or "fluid hammer" caused by overpressure or air in the accumulator/pump system. Some people have replaced the accumulator and it solved the issue, but some found it made no difference. Others have replaced the motor/pump/accumulator and found it fixed the issue, but others found it made no difference.

After much research and troubleshooting, I found that my high pressure switch within the ABS module on the side of the master cylinder, which is supposed to shut off the motor/pump once proper pressure was reached, was not operating correctly for the first several minutes in the morning. I could tell this by reading the electrical signals from the switch, as well as the fact that I was able to stop the sound temporarily by pumping the brake pedal a few times, lowering pressure in the system. This told me that the motor and pump were operating fine, but were attempting to over pressurize the accumulator. Unfortunately this pressure switch (as well as the low pressure switch) are not replaceable. I could have replaced just the master cylinder/ABS module (without the motor/pump/accumulator) for ~$1200, but on the off chance that my problem WAS with the accumulator or pump, I didn't want to be having to take it all back out again to replace more parts. I just wanted it fixed. So I opted to replace the whole unit for ~$2200. It's been peachy since.

Unit removed:


Old unit removed and kept for spare parts:


New unit:


New unit installed:

[BoomerBob]

Originally Posted by rightyouareken

Yeah, some have tried rebuilding their motors with varying levels of success. FWIW, our brake systems are very similar to 100 series Landcruiers, FJ Cruisers, and even the 4th and 5th gen 4runners and new Tacomas. They all have the same motor driven pump/accumulator style brake boosters. Maybe they sorted some of the problems since our first gen units, but who knows.

There is lots of info on the forums over at ih8mud.com which is the Landcruiser forum.

After much research and troubleshooting, I found that my high pressure switch within the ABS module on the side of the master cylinder, which is supposed to shut off the motor/pump once proper pressure was reached, was not operating correctly for the first several minutes in the morning. I could tell this by reading the electrical signals from the switch, as well as the fact that I was able to stop the sound temporarily by pumping the brake pedal a few times, lowering pressure in the system. This told me that the motor and pump were operating fine, but were attempting to over pressurize the accumulator. Unfortunately this pressure switch (as well as the low pressure switch) are not replaceable. I could have replaced just the master cylinder/ABS module (without the motor/pump/accumulator) for ~$1200, but on the off chance that my problem WAS with the accumulator or pump, I didn't want to be having to take it all back out again to replace more parts. I just wanted it fixed. So I opted to replace the whole unit for ~$2200. It's been peachy since.

How many miles on your 02 when this was done?

[BoomerBob]

Originally Posted by rightyouareken

FWIW, if your motor does go, you don't actually need to replace the whole master cylinder/ABS module assembly if you don't want to. The pump, motor, and accumulator are available as a unit for about $750 new:

1998-2007 Toyota Brake Booster 47070-60010 | Boch Toyota South

Unfortunately, when my master cylinder kicked the bucket, the failure was with a pressure switch internal to the ABS module, so I ended up replacing the whole unit. That was a bit of a bitter pill, but it's nice to know it should be good for another ~170k miles.

I hope some enterprising shop figures out how to rebuild those and replace the switch without having to buy a $1200 or $2200 complete brake setup. That's crazy money for something like that. I think I'd buy a used ebay unit before spending that kind of cash but then I'm cheap that way.

2001-2002 Toyota 4Runner ABS Master Cylinder Brake Booster Complete Assembly OEM | eBay

[brillo_76]

I am honestly surprised Toyota isnt rebuilding these brake and throttle body assemblys.. Way too much money in these for a few components failures..

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[brillo_76]

Originally Posted by BoomerBob

I hope some enterprising shop figures out how to rebuild those and replace the switch without having to buy a $1200 or $2200 complete brake setup. That's crazy money for something like that. I think I'd buy a used ebay unit before spending that kind of cash but then I'm cheap that way.



2001-2002 Toyota 4Runner ABS Master Cylinder Brake Booster Complete Assembly OEM | eBay

Look even comes with the cut off connectors...LOL

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[rightyouareken]

Originally Posted by BoomerBob

How many miles on your 02 when this was done?

About 168k miles. Seems on the short end of what people are getting from them, but I think it was used for a lot of around town running...so a lot of brake cycles. Who knows.

Originally Posted by BoomerBob

I hope some enterprising shop figures out how to rebuild those and replace the switch without having to buy a $1200 or $2200 complete brake setup. That's crazy money for something like that. I think I'd buy a used ebay unit before spending that kind of cash but then I'm cheap that way.

2001-2002 Toyota 4Runner ABS Master Cylinder Brake Booster Complete Assembly OEM | eBay

I completely agree there should be a market for rebuilt units. I intended to take my old one apart to have a look at the switch and ABS valve assembly, but haven't done so yet. It's possible all the switch needed was some cleaning or something.

FWIW, I considered buying used, but I didn't want to risk blowing $500 for something that might put me right back where I started. There's really no way to easy test these units without installing them in the vehicle that I can think of, without building a test rig of some sort.

Ultimately, though there may have been cheaper ways to fix my issue, at least temporarily, I was tired of dealing with it and just wanted my truck to work properly so I could take it offroading into the sticks with confidence.

[BoomerBob]

Originally Posted by rightyouareken

About 168k miles. Seems on the short end of what people are getting from them, but I think it was used for a lot of around town running...so a lot of brake cycles. Who knows.



I completely agree there should be a market for rebuilt units. I intended to take my old one apart to have a look at the switch and ABS valve assembly, but haven't done so yet. It's possible all the switch needed was some cleaning or something.

FWIW, I considered buying used, but I didn't want to risk blowing $500 for something that might put me right back where I started. There's really no way to easy test these units without installing them in the vehicle that I can think of, without building a test rig of some sort.

Ultimately, though there may have been cheaper ways to fix my issue, at least temporarily, I was tired of dealing with it and just wanted my truck to work properly so I could take it offroading into the sticks with confidence.

Very informative thread. I've bookmarked it under T4R 'learning'.