Brake problem approach

I'll put the charger on and get the battery voltage up. Maybe keep it on during the test. If the warnings go away, boy will I feel stupid. Checking the 12V should always be the first step.

Bob Wilson

 

I put the 12V on a charger but it had no effect on the brake problem. So it is time to take a 'road trip' to the salvage yard.

Before leaving, I'm building a special connector so I can check the junk yard, brake boosters before taking the hour or so to pull one out. The problem is the pump connector is 90 degrees so you can't even see the blades. The tests are:

• check the resistance range
• apply 12V and feel the motor running

I'll make a quick-and-dirty and test on the 03 Prius. Then when I get to the junk yard, I'll cannibalize the first vehicle checked; solder up some longer leads, and; test that one and the rest. My KLUDGE connector is just in case I have any issues getting a plug.

BTW, my OEM Windows 7 software arrived and installed. I had to make a disk image file on my DVD Mac and then mount the image file on the TechStream testing system. Right now I'm getting all the Windows updates, 951.3 MB. I'll make sure Java is current and use this as my base. After making a copy, I'll install TechStream and we'll see if I can get the actual codes instead of using the flasher (i.e., jumper OBD.)

Bob Wilson

 

Finally got TechStream, V13.00.022, running on Windows 7 under Virtual PC. The next task is building the jumpers to test the booster pump:

• measure resistance
• apply 12V to see if pump runs

Once I get to the salvage yard, I'll get one of the plugs and rig up a proper jumper tester.

Bob Wilson

 

Wednesday I went to the salvage yard to look over the inventory and get a connector for the brake power boost:

The brake booster connector is at a 90 degree angle, impossible to see in the car. Yet the diagnostic manual says to:

1. Measure resistance
2. Apply 12V to see if the motor runs

I'll use this to screen the brake boosters in the yard before spending the hour or so to remove what may be a bad booster. I trimmed the latch so it won't lock in the brake booster connector.

Bob Wilson

 

The test fixture works. I measured an open circuit to the motor. So I looked closely at a brake booster on eBay and noticed something new.

Notice the small black box, looks like a fuse box, between the connectors and the accumulator cylinder:

Time to open the cover an see if there are fuses. If one is blown, this may turn out to be an easy if undocumented fix.

Regardless, it looks like there are three main bolts at the bottom that hold the brake booster in the car. If I take out the wheel well liner, those three bolts should be readily accessible from the bottom:

I've already found the four bolts on the bottom.

Bob Wilson

 

I pried open the little black box:

It appears to be the control electronics for the motor, not a hoped for fuse.

Time to head to Nashville; test the salvage brake boosters, and; drop one to replace this one.

Bob Wilson

 

Lesson's learned:

• It takes ~3 hrs each way - South Huntsville through town to North Nashville, ~105 mi. Left just after 8 AM and in the salvage yard at ~11 AM. The car I was planning to pull the brake booster, I couldn't find. So I worked on another one. I had taken the brake fluid tank out of the one I'd been working on.
• With hand tools, it takes about ~45 min to remove the wipers, cowling cover and access the booster. Using the test connector: 4.6 ohms, and 12V made the motor spin. The test connector can be made in the field by bringing wire strippers, crimper, and a pair of ~2 ft, #22-#18 wire. Using a screwdriver, pull off the connector, strip and extend the left connector going into socket, B+, and right, to nominal ground. I trimmed the plug to defeat the lock. Then measure the resistance, ~4.5 ohm, and using a 12V power tool battery pack, test the model to hear it spin up.
• Knowing the brake booster is good, the next step is to remove and drain the brake fluid INTO A BOTTLE. You do not want to sit in a puddle of brake fluid and deal with slippery parts. However, the old fluid can be used to clean the exterior later.
• Removal out the top would require removing the AC and heater coolant pipes making replacement in the repair vehicle, a bad thing. So I took the wheel well cover out and the engine cover too. A 10 mm socket took them out quickly along with one cut with a hand saw. The drink bottle on the ground holds most of the brake fluid. Preserve them on the repair car. On the repair vehicle, with the wheel removed, have it turned to the right to make access easier. Adjust height of car to make it comfortable to work under the wheel well.
• Here we have clear access to the bottom of the triangular piece the base for the booster.

I stopped taking photos trying to get the assembly out before the yard closed at 5 PM. Tools needed:

• 12 mm socket and open ended wrenches - the structural pieces
• 10 mm socket and open ended wrenches - everything else but the two hydraulic pipes
• 9 mm or bolt cutter to take the out the two hydraulic pipes BUT this exposes the female port. Using bolt cutters would minimize contamination until the part is removed and cleaned. Trying to unscrew the hydraulic couplers with the wrong tools UGH! and lost a lot of time. Crescent wrench better than nothing but often very little rotation due to tight area.
• 2 ft socket extension or break-over to reach one 12 mm nut located at the apex corner

By 4:30 PM, I was getting cramps and was faced with a hard problem. There are two, threaded studs, one from the firewall and the other the passenger side of the engine compartment. About 2 cm long and at a 90 degree angle, they are the only mechanical pieces still holding the triangular base in the car. <AGGGGHHHH!!!!>

My first thought was a battery operated Dremil tool but the salvage yard take a dim view of sparks and fire in their inventory. Does brake fluid burn?

Bob Wilson

 

I am using the removal as my guide for installation. I’m also trying to document how to do it and lessons learned.

Bob Wilson

 

My current thinking:

• The passenger side quarter panel is most easily worked on as the passenger side firewall is backed by the hybrid ECU assembly.
• Use a plumb bob to measure the height and forward-back offset. Then scrape the protective, outer layer to located the stud.
• Use a 12 mm nut and bolt to extend the stud. Then hammer it to back it out.

Hummm, I wonder if I call it a hydraulic pump instead of a brake booster I can get it for less.

Bob Wilson

 

I got the part:

I didn't have a cold chisel so I used one crescent wrench on the pipe and a second on on the handle. A little rocking motion and metal fatigue severed the pipe. I then pulled the end pieces out of the way:


Working the four, 10 mm bolts on the bottom, all had variable amounts of rust making them difficult to remove. The fourth bolt made it easy by twisting off the head:

BTW, the effort needed to remove these four, rusted bolts also deformed the triangle piece to take it off of one of the 90 degree threaded studs.

After cutting trimming the 1.5" (4 cm) diameter cables, the last 12 mm bolt was revealed. Quickly unscrewing, the hydraulic pump and accumulator were released. Note I'd already cut the wires pan the second connector ... car side:


Gravity tried to find a way to drop through the front steering and drive assembly ... it didn't work:


With pipes and wiring out of the way, I brought the assembly up only to find the metal plate holding the fuse box made removal impossible. Cut all of the wires to the fuse box and then find the three, 12 mm bolts holding it on:

My only 3/8" drive, 12 mm socket slipped and remains in the donor car frame ... sacrifice to Murphy, the God of Engineering.

Here is the fuse holder fixture moved out of the way. I was then able to noodle the hydraulic pump out:


Third round trip to Nashville and back. The first, salvaged a connector needed to test the unit. The second trip started removal but more of here is the roadmap. Third trip, opened the top and was able to remove the part.

The salvage yard charged $75. Trips, labor, cuts and scrapes ... priceless.

Bob Wilson

 

Removal synopsis:

IDENTIFY USABLE PART

Scanning can be done in 20-30 minutes but It will take several hours to remove the part. First scan the part to make sure it is working.

You'll need: 12-18V hand tool battery pack; short jaw wire cutter and stripper; two ~18" hookup wire (color coded) ; wire crimps; cheap VOM; small flat screw driver; 10 mm and 12 mm sockets and box/open ended wrenches, and; Phillips head screw driver.

Remove the windshield wipers and cowl covers. At first donor car, disconnect one of the two connectors and cut the connector and wire on the car side.


Here the easy to reach connector has been removed from the part:


Splice the hookup wire to the larger wires on the connector with the one closest to firewall coded as B+. Optional, defeat the connector locking tab. Put the connector on the pump and measure resistance, ~4.5 ohms. If open or shorted, look for another donor car. Then apply 12-18V, B+ closest to firewall, and listen for the motor to run. If it runs, you have a salvage part.


REMOVAL

This will take several hours so work carefully with deliberate speed. Taking it out the top, the least risky and fastest way, involves cutting and bending pipes, wires, and steel brake line. Going out the bottom risks running into suspension and drive disassembly issues, a huge time risk.

You'll need in addition to the above: safety glasses to avoid debris and brake fluid in the eyes, couple of empty water bottles for the brake fluid; cold chisel and hammer; wire/metal cutters; two crescent wrenches; drive extensions; a break-over bar; spare 10 mm and 12 mm sockets; medium vice grips (your 3d hand); penetrating oil, and; general purpose strap. WARNING: salvage yards don't like sparks from grinders or Dremel tools ... big fire hazard!

The goal is to remove the hydraulic pump and accumulator:

Note the four bolts attaching the hydraulic pump and accumulator to the triangular piece bolted to the firewall and passenger side quarter panel. There are two, threaded studs and 90 degrees that make removal difficult. So we'll go after the four bottom attachment bolts ... the well rusted, frozen bolts:

The quarter panel, threaded stud is in the lower left. This taken under the car while resting on the well padded, rear seat cover. The seat back can be used to block direct sunlight as needed.

To access the bottom of the car, you'll need to remove the wheel wheel and lower engine covers:

The bottle on the lower right holds some of the brake fluid.

From the top, unbolt the brake fluid reservoir and with the empty bottles, drain and collect the fluid instead of making a puddle you'll soon be lying in. Then you can remove the overhead hoses and put the container aside:


Here the vice grips are holding the reservoir to make removal and draining easier:


The tank is mounted on a metal piece, lower left, held by three, 12 mm bolts. This has to be taken out before the hydraulic pump and accumulator can be removed:

To the right of the accumulator bottle is the plastic engine cover that makes removal more difficult than it needs to be ... snip snip.

Here is the mount for the brake fluid tank that must be removed to allow the brake pump and accumulator removed:

There is also a plastic shield on the back of the engine that trimmed makes removal a little easier.

Let loose your inner Vandal and remove and cut every overhead hose and wire bundle. Leave the red coated, brake line attached. The others, use the wire/metal cutters. Avoid unscrewing the uncoated, brake line. Here I'm using the rocking crescent wrench technique on an aluminum pipe:


This completes 1/3 of the task and 90% remains.

Bob Wilson