Brake booster compatibility?

[Ayune]

Today I pulled some misc. parts from a wrecked ‘04 LX and grabbed the brake booster to keep as a spare in case my ‘98 LC’s booster dies. They are definitely different, though. For example, the LX uses four outputs while my LC uses only three. There’s also an extra circular connector on the LX unit.

My question is: Will this assembly be useful to me if/when my booster fails? Are the failure-prone internals shared between the two trucks (like the accumulator pump), and could I use parts from the LX assembly to fix the LC’s?

This is the one from the LX with 140k miles:

This is my ‘98 LC’s booster, with almost 300k on it, obviously a different PN.

 

[hoser]

The motor, accumulator, reservoir tank and master cylinder rebuild kit are the same for all years. The difference is mainly VSC vs non-VSC but I don't know if you could actually swap the VSC/ABS parts onto a 98-99 master cylinder.

 

[eLX470]

Today I pulled some misc. parts from a wrecked ‘04 LX and grabbed the brake booster to keep as a spare in case my ‘98 LC’s booster dies. They are definitely different, though. For example, the LX uses four outputs while my LC uses only three. There’s also an extra circular connector on the LX unit.

My question is: Will this assembly be useful to me if/when my booster fails? Are the failure-prone internals shared between the two trucks (like the accumulator pump), and could I use parts from the LX assembly to fix the LC’s?

This is the one from the LX with 140k miles:
View attachment 1884570
View attachment 1884568

This is my ‘98 LC’s booster, with almost 300k on it, obviously a different PN.
View attachment 1884569

Hey, I know I am coming a bit late to the party but could be valuable stuff for others that are in the same boat, and who probably are coming to this forum asking these questions. Inevitably, our rigs are getting old so parts like these are going to be big needs, but if you have spent any time at all asking around your local parts counter you will surely be in sticker shock when trying to price out a new replacement... I paid less for the whole car than the master brake assembly costs at the dealer.

So, the PO found himself a newer unit exactly as you did from a salvage yard. Installed it onto the LX470, and to date have not run into any issues. I took the car down to Miami and back ( from Atlanta) last year and no issues. I will try to get a picture this evening of how I have it set up, but basically, the PO installed it, capped that 3rd line, and just didn't connect the additional connector.

When I brought this up to the others on the forum here, I was told that it was a bad idea and could cause complications. Great, thank you for the warning, but ultimately I never got a concrete response as to "why" its a bad idea or actual repercussions of the swap. I seriously would love to know what I should watch out for or what could happen. I just cannot justify spending 3k on a brake master cylinder. Toyota is nuts sometimes with pricing.

I am at 378k miles on the rig ... so far so good.

 

[Ayune]

Hey, I know I am coming a bit late to the party but could be valuable stuff for others that are in the same boat, and who probably are coming to this forum asking these questions. Inevitably, our rigs are getting old so parts like these are going to be big needs, but if you have spent any time at all asking around your local parts counter you will surely be in sticker shock when trying to price out a new replacement... I paid less for the whole car than the master brake assembly costs at the dealer.

So, the PO found himself a newer unit exactly as you did from a salvage yard. Installed it onto the LX470, and to date have not run into any issues. I took the car down to Miami and back ( from Atlanta) last year and no issues. I will try to get a picture this evening of how I have it set up, but basically, the PO installed it, capped that 3rd line, and just didn't connect the additional connector.

When I brought this up to the others on the forum here, I was told that it was a bad idea and could cause complications. Great, thank you for the warning, but ultimately I never got a concrete response as to "why" its a bad idea or actual repercussions of the swap. I seriously would love to know what I should watch out for or what could happen. I just cannot justify spending 3k on a brake master cylinder. Toyota is nuts sometimes with pricing.

I am at 378k miles on the rig ... so far so good.

Thanks for the info. I'd like to know if you've yet to trigger the ABS? A dirt road test (with a GoPro trained on each wheel ) would be much appreciated!

The main question is: If a newer model's ABS controller is expecting input from 4 sensors, but is retrofitted to an older model with only 3 sensors, what's gonna happen when ABS is triggered?

Is the unused connector for the fourth sensor?

Is the third sensor still being monitored?

Will the third sensor trigger pulsing to your rear (shared) brake lines? Or the capped 'extra' line?

----
Background info: Our early-year LC & LXs have a 3-channel system, whereas later years have a 4-channel system:

"The three-channel, three-sensor ABS provides both of the front wheels with an individual valve and speed sensor. However, the rear wheels must share one valve and one speed sensor, which is located in the rear axle."1

"The four-channel, four-sensor ABS system allocates a different valve for each wheel and also a separate speed sensor for each of the four wheels."1 (4-channel system is also required for VSC.)

1: Types of ABS Systems - ACA Auto

 

[Amplificus]

Having just encountered the failed accumulator pump, I would say to first check the electrical contacts under the boot attached the the motor on the bottom of the unit. if those are clean, then it is a good sign.

 

[awkragt]

So I'm undertaking this test as well. I ordered a new unit for my Non-VSC 1998 but mistakenly ordered 47050-60041 instead of the non-VCS 47050-60012. Plugged the unused 4th brake line hole and didn't plug anything into the pressure sensor. So far everything is working fine just like normal and hard braking on wet pavement is just as it was before. My guess is that the casting and internals are the same as even on the 3 circuit casting it has the plugged hole labeled "L". The old ABS systems like this are not sophisticated enough to apply braking to individual tires.