Brake actuator replacement in pictures

[galaxee]

ADVANCE NOTE: THIS IS NOT A DO IT YOURSELF JOB. THESE ARE NOT INSTRUCTIONS. REPLACING THE ABS ACTUATOR IS A JOB FOR A QUALIFIED TECHNICIAN WITH PROPER EQUIPMENT.
I REPEAT: YOU CANNOT DO THIS AT HOME.

Our 05 Prius with just under 60k miles started doing the brake “bark” sound on me not too long ago. There is a TSB out for the issue, but the job is only covered under the 3/36 warranty. Since we got the extended warranty here at PC, we figured this was an opportune time to use it.

Part: 1769.07
Labor (5.5 hours): 407.00
Supplies (fluids): 25.30
Total: 2322.49
Our cost: 0
Extended warranty just paid for itself a couple of times over…

DH took it to the only other tech who is allowed to touch our car. And being DH, he also ended up insisting on doing most of the work. (which is a no-no, but he’s kind of an exception since he used to be a ‘yota hybrid tech himself and knows the right people.)

Ok, first things first. The resistor pack gets replaced first, because it’s under the dash and that type of interior work is best done with clean hands. The resistor pack is replaced along with the inverter because they are made and serviced as matched sets. If they’re replaced separately, they get less quiet.







Next, some digging around under the hood. The inverter has to come out. So the whole wiper cowling setup has to come out. Next, clamping of coolant hoses and removal of various plugs inside and outside the inverter case to be able to pull it out.



Like the inverter crash sensor


Battery connections [yes, the safety plug is removed and the 12v is also disconnected.]


MG connectors


Other internal connectors


Even more MG connectors

disconnected


Even more connectors


And a shot of the whole thing minus cover


And out goes the inverter! First look at the actuator- it’s got the sticker with the big B on it.


Engine electric water pump (big black thing in the center)


Brake fluid line non-pressure hose disconnected in preparation for removal of the actuator


Actuator now out, with bracket


A better profile shot- you can see the solid iron vibration dampener that it bolts to as well


Old actuator part- note that the accumulator tank end is rounded.


New actuator part- here the accumulator tank end is flat. The early actuator replacements were with the same part. This one is now different.


Lots of fun to put everything back together. Then the brake bleed and inverter bleed via the Toyota scantool- allow me to reiterate the only possible way to bleed the brakes on this car is with the Toyota scantool. DH always bleeds the inverter first because an inverter without coolant is bad news, and you might as well do it right when you add the coolant back. Then brakes- by this time, the car is angry and throwing codes left and right because there is air in the brake lines.

So far no more brakes barking! It hasn’t been very cold since the job was done, though, and the sound was associated with cold weather. The accumulator pump seems a little quieter, too.

[Patrick Wong]

Hi Galaxee,

Thanks for providing the photos and the steps behind that job. Truly fascinating.

Yesterday, having the cowl off my 2004 to do some routine maintenance, I was nosing around that area. I took a couple of photos on the passenger side of the cowl focusing on brake parts, and wanted to ask for your (or your DH's) comments.

The first photo is of the brake stroke simulator, I believe. Can you confirm?

The second photo seems to be some kind of horn but I can't find it in the repair manual. That is located below the brake stroke simulator. Is that the horn that provides warning when the brake system has a serious problem?

Thanks!

[galaxee]

Patrick-
why are we not surprised you're the first reply?

your first picture looks very much like the stroke simulator. if it was on the passenger side, that is likely it. the second is probably the anti-theft horn. it's buried way in the engine compartment so it's not easy to just clip off during a theft attempt. the brake problem buzzer is in the interior of the vehicle, he spent some time listening to that yesterday.

[jayman]

Hmmm only slightly less complicated than building your own nuclear bomb. I'm sure he had fun with that job

[hobbit]

Wow, great stuff! I have some additional pix of the actuator
and its relationship to the inverter in my maint50k page
and managed to avoid dropping the inverter too heavily onto the brake
lines during all that, but have never actually cracked any of the
coolant lines for that process or cleaning the throttle body. Never
had the inverter completely out of my car, obviously.
.
What's with the "resistor pack", what does it do? I think I've seen
it up under the dash [left side next to the sidewall, right?] but
never really knew what subsystem it was for. You didn't change the
brake ECU during this, correct?
.
How many hands/fingers at once did it take to perform the initial
bleeding? The manual implies that it takes at least two people to
start the process and get the rest of the lines hooked up, before
the scantool stuff even begins.
.
The brake beeper is definitely inside, mounted right on the ECU,
visible in this pic from the wheel-speed-diff page next to all the
metal spikes that form the brake-ECU heatsink. [Why heatsinked?
Because all the solenoid drivers for the actuator are in the ECU.]
Pulling the two pump relays and playing with the pedal is a good
way to make it start howling, if anyone's curious to mess with it.
.
_H*

[galaxee]

Originally Posted by jayman

Hmmm only slightly less complicated than building your own nuclear bomb. I'm sure he had fun with that job

he enjoyed getting back under the hood. and yeah, only a little less complicated.

[galaxee]

Originally Posted by hobbit

What's with the "resistor pack", what does it do? I think I've seen
it up under the dash [left side next to the sidewall, right?] but
never really knew what subsystem it was for. You didn't change the
brake ECU during this, correct?

that is indeed its location. the resistor pack is for the pump motor. he's not sure why its actual purpose is, and why it couldn't be built into the unit itself. but... there it is.

no change of brake ecu.

How many hands/fingers at once did it take to perform the initial
bleeding? The manual implies that it takes at least two people to
start the process and get the rest of the lines hooked up, before
the scantool stuff even begins.

the r&r and bleed initiation can be done by one person. the brake bleeding procedure is a little less difficult than the manual has led you to believe- but just a little. one person can do most of a bleed, but it takes about twice as long as two people. there is one point where you do need two people, but it's brief.

[Patrick Wong]

I looked in the repair manual, and this says: "Be sure to replace the actuator and the resistor together. If they are not replaced together, motor noise may be increased."


However the 2004 wiring diagram manual, Brake Control System section, does not show the resistor assembly so it is very strange.

Also, to remove that resistor it looks like the instrument panel has to be disassembled to the point where the passenger airbag can be removed, so it seems that part of the repair is not a minor effort.

[galaxee]

you have to pull the MFD to pull the dash panel high enough to reach it, but not the entire dash.

[Mike Dimmick]

Originally Posted by Patrick Wong

I looked in the repair manual, and this says: "Be sure to replace the actuator and the resistor together. If they are not replaced together, motor noise may be increased."

However the 2004 wiring diagram manual, Brake Control System section, does not show the resistor assembly so it is very strange.

Psst, 2006 manual here. Keep it quiet. (Despite the EU URL, this is the North America manual.) Either there wasn't a resistor there on the 2004-2006 car, or they didn't think it was going to need replacement and didn't mention it. It could be that the resistor has to be a specific value to perform whatever task is necessary (motor speed control?) and the motors are actually varied enough in winding resistance that they can't use the same resistance on all cars.

I wouldn't be surprised if the complaint that the motor was too noisy was 'fixed' by adding resistance to reduce the voltage across the motor, making it spin slower.

Originally Posted by Patrick Wong

Also, to remove that resistor it looks like the instrument panel has to be disassembled to the point where the passenger airbag can be removed, so it seems that part of the repair is not a minor effort.

I'd guess that the resistor is in that odd place so it's in the cabin air flow. It looks like it dissipates quite a lot of power.