Are you afraid to change pads in a Toyota Prius? Well, it should; if you treat it like any other vehicle. But, if you know a few things in advance, the job can be done like any other bridle job.
- - Locking hubs and axles
- - How regenerative braking works
- - Detection of faults in the brake system
Don't worry about high voltage. Worry about angry customers due to recalls because the brake/ABS light is on. Servicing a Prius doesn't require a lot of special tools to replace the front brake pad. All you need is normal hand tools and maybe a scan tool and software that can read chassis codes if you're out of luck or need to replace your hydraulics. But it's possible, according to Toyota, to replace the pads without a sweep tool.
There are three basic principles that technicians need to keep in mind before pushing back on front caliper pistons. First, the most important basic for any technician to understand is that the Prius' brake system has pressure sensors in the master cylinder and wheel outlets. These sensors check the pressure and any abnormality between the two pressures will cause a trouble code to set.
Second, when the driver presses the brake pedal, it may not produce hydraulic braking force on the wheel. The system measures the stroke and pressure generated in the brake pedal and translates it into braking force created by a generator. The system is not a full-time wire brake system. Hydraulic brakes are used during hard stops and at speeds below 16 km/h. When regenerative braking kicks in, it gives feedback to the driver with a device called a "racing simulator".
Finally, even with the engine off and the car stopped, there is still hydraulic pressure in some of the lines. The Prius can drive without the internal combustion engine running. Also, even if the car is parked with the engine running and the keys in the ignition, the engine could start to charge the battery or operate the HVAC system. Keys must be outside and away from the vehicle during service. If you keep these concepts in mind, you can perform any brake job with the right tools.
The Prius was released in 2001. The rotor and caliper are the same as the Echo, Scion Xa/Xb and MR2. In 2004, Toyota changed the brake system by upgrading the batteries and electric motor. The most striking difference is the lack of a vacuum brake booster. In 2004 a different ECU and a larger accumulator and pump provided the boost.
Behind the wheel, the system remained the same as far as rotor and caliper were concerned. However, the characteristics of the brake pads have been changed for better longevity and corrosion resistance.
At the rear, there are drum brakes without regenerative braking. The rear drum brake is nearly bulletproof. But there were some problems with the cables for the emergency/parking brake and the electric motor that drives the system. TSB BR002-07 describes how to troubleshoot the brake light that remains on after the emergency/parking brake has been released. This procedure will require a scan tool
It's not uncommon to find a Prius with 70,000 or 100,000 miles on it with the original set of pads. This is due to regenerative braking which generates most of the braking force. But that doesn't mean other components like hardware and rubber seals/covers can't fail sooner.
The Prius has unique requirements for the braking system. On 2001-2004 models, the hydraulic brakes were not used until the vehicle was below 7 mph or if the vehicle had to come to a sudden stop.
Most of the time, the pads never reach conventional operating temperatures and corrosion between the backplate and the friction material can occur because the pads never dry out. On some vehicles, corrosion between the friction material and the backplate would cause complete separation.
Always use a high quality pad for Prius and other hybrid applications to avoid problems. It's not a matter of better performance. It's a matter of quality and engineering.
Since it is impossible to perform a conventional break-in/break-in procedure on your test drive, make sure the manufacturer promises excellent performance right away. Also, applying a non-driving finish with a ball polish will help the new pads evenly deposit a layer of friction material on the new rotor.
The Prius uses a two-part wedge. The solid piece is the anti-noise layer. The perforated part provides lubrication and acts as a bearing. The contact areas of the two wedges float in the lubricant and slide during application. Always replace the wedge and do not reuse an old wedge!
There's nothing special about keeping the rotors on this vehicle. But, if you plan on using a brake vise on your car, make sure the system is off for two minutes. Most car brake lathes operate below the speed limit of the generator's ability to generate voltage.
Impellers with excessive offset or thickness variation can cause hydraulic pulsations in the brake circuit. These irregularities can cause the pressure sensor to activate trouble codes C1341 through C1344 which indicate a malfunction in the hydraulic circuit.
hydraulic componentsIf you ever need to replace a caliper, wheel cylinder, or brake hose, you should have a scan tool that can clear codes and run the ABS pump while bleeding. Manual or “one man” bleeding will not work on this vehicle due to the valves and solenoids that manage regenerative braking. Also, the system must be turned off to prevent component damage. Also, read all precautions in the service information before attempting to replace any hydraulic component.
brake pad replacement
- Raise the car and remove the wheels.
- If work that does not involve bleeding the brake fluid, such as disc brake pad replacement, is started two minutes or more after turning off the power switch, Brake Control/Brake Control Override (ECB) it is not necessary.
If you are replacing calipers or other hydraulic components, you will need to disable the system with a sweep tool. Most scan tools will guide you through the process which involves removing the two ABS pump relays and pressing the foot pedal in sequence to depressurize the system. The system can also be disabled by waiting two minutes after turning off the switch, stopping brake pedal operation and closing the driver's door before removing the two relays (see photo).
Also, it is good practice when working on vehicles with advanced ABS and Stability Control systems to remove the keys from the vehicle and place them in a different room, such as the front counter.
- Remove the two bolts and lift the front disc brake caliper off the sliding pins. Make sure you have a 17mm flat end wrench to access the hex head screw on the inside of the slide pin. Attach the caliper to the bracket with a hook or loop.
- Remove pads and inspect friction material for glazing, corrosion, edge lifting or other mechanical damage. Using a ruler, measure the pad liner thickness from the bottom of the backplate to the friction surface. Also, make sure the inner and outer pads are evenly worn.
- Standard thickness: 11.0 mm (0.433 in.).
- Minimum thickness: 1.0 mm (0.039 in.).
- Remove the two anti-squeak wedges from the pads.
- Remove the caliper brackets. Inspect surfaces for corrosion and mechanical damage.
- Remove the slide pins, dust caps and pad holder clips from the caliper holder. Clean the bracket with brake cleaner. Be sure to remove all old grease from the slide pin holes.
- Check front wheel bearing play and misalignment on axle hub before removing impeller. Secure the front disc with the nuts (torque: 103 Nm or 76 ft/lbs).
- Using a micrometer, measure the rotor thickness in at least six areas.
- Standard thickness: 22.0 mm (0.866 in.).
- Minimum thickness: 20.0 mm (0.787 in.).
- Check the runout by holding a dial indicator 10 mm from the outside edge of the rotor. Maximum disc eccentricity: 0.05 mm (0.0020 in.). Before removing the impeller, mark the high and low offset points. Also, mark the position of the rotor on the hub. If you do, you can change the rotor and shaft mounting positions to reduce the offset. After removing the impeller, measure the runout on the hub face and mark the high and low points.
- Machine the rotor with a bench or automotive brake vise.
- Fit the new brake pads. If using stock shims, apply high temperature disc brake grease to the contact area of the #1 anti-squeal shim. Install the two #1 anti-squeal shims and the two #2 anti-squeal shims on the brake pads front disc.
Do not use excessive amounts of grease which could contaminate the friction material after the brakes are warmed up.
- Install the caliper brackets with the two screws. Torque: 109 Nm, 81 ft/lb).
- Install the front disc brake cylinder sliding pin. Toyota recommends lithium soap-based glycol grease. Push the front disc brake cylinder slide pin into the boot and install. Make sure the dust cap seals are in the grooves on the pins.
- Install the support clips onto the caliper support surfaces. A specific high temperature brake grease can be used on the surfaces that make contact with the pawls or pad ears. Apply only a very light layer.
- Install the pads into the caliper holders. Toyota advises that the brackets (pillar clamp) have sufficient bouncing when installing the pad. Also, check the block for excessive play after installation. This can lead to brake friction and increased fuel consumption.
- Gently push the caliper piston just enough to seat over the new pads and shims. Toyota says that it's not necessary to break the bleeders during this procedure and it can cause more problems than it solves. If you are comfortable blocking the brake hose and breaking the bleeders to remove displaced brake fluid, you can do it this way. See TSB BR0012 for more information.
- Install the brake calipers. Torque: 34 Nm or 25 ft/lbs).
- Install the front wheels. Torque: 103 Nm or 76 ft/lb)
- With the car still off and the key out of the ignition, step on the pedal a few times to bring the pads into contact with the rotor.
- Check the fluid level in the reservoir. Adjust the brake fluid level to the MAX line with the ignition switch (IG). The brake fluid level must be set to the MAX line.
- Test the vehicle. Be sure to make several stops at 0 mph and at least one hard stop. If the ABS warning light doesn't come on, you're done. If an ABS light comes on, you'll need to take some additional steps.
ABS light on?
If the ABS light comes on during the test drive, disconnecting the battery is not the way to clear the codes. Yes, it will clear some codes, but you will have to recalibrate the steering wheel position sensor and other items like the power windows will stop working.
What happened during the test drive is that the pressure sensors in the wheel detected an abnormal reading when the hydraulic system was first engaged. The system may have detected low pressure when additional fluid is needed for the piston to contact the rotor or residual pressure when the piston is pushed back. DTCs can be stored if brake fluid leaks, the wheel cylinder vibrates due to uneven brake disc rotor wear, or if foreign material gets into the solenoid valve.
Toyota issued Technical Service Bulletin BR012-06 on the matter. It states, "When replacing the brake pads on a vehicle equipped with an ECB (Electronic Controlled Brake) system, retracting the caliper piston and installing new brake pads may cause trouble codes to be set the next time the pedal is cycled. held down." of the pedal. brake".
If any of the following four trouble codes are established, all codes should be cleared and another test drive completed to verify the code has cleared:
- C1341 Right Front Hydraulic System Malfunction
- C1342 Left front hydraulic system failure
- C1343 Right Rear Hydraulic System Malfunction
- C1344 Left Rear Hydraulic System Malfunction
If you don't have a scan tool, it is possible to clear the codes with the Special Service Tool (SST) 09843-18040 (basically a fancy jumper wire).
(a) Using SST, connect the DLC3 TC and CG terminals.
(b) Turn on the power switch (READY).
(c) Clear DTCs stored in the ECU by pressing the brake pedal eight times or more within five seconds.
(d) Check that the warning light indicates a normal system code.
(e) Remove the SST.
Note: DTCs cannot be cleared by removing the cable from the negative (-) battery terminal or the ECU-IG fuse.
In May 2008, Toyota announced that its cumulative worldwide sales of the Prius had passed the 1 million mark. Nearly 60% of all Prius sales were in North America, where 183,800 vehicles were sold in 2007. This is a significant opportunity for retailers as the age of the hybrid fleet begins to age.
You won't have to wear insulating gloves or rubber-coated tools to work on the brake system, but you will need to arm yourself with knowledge.
TSB BR002-07: The parking brake warning light stays on after the parking brake pedal is released.
Models: 2004 –2007 Prius
Some customers of 2004-2007 Prius vehicles may complain that the parking brake warning light stays on after the parking brake pedal is released. The parking brake assembly, which includes the parking brake switch, has been modified to correct this condition. Use the following repair procedure to remove and replace the parking brake pedal assembly.
(Includes model year 2004 - 2007 Prius vehicles produced BEFORE the current production change in VINs from JTDKB20U#73249043 to JTDKB20U#77632091.)
- Confirm customer complaint that the parking brake warning light stays on after the parking brake pedal is released.
- Check the parking brake switch for looseness and/or the plastic guide pin on the parking brake switch for breakage. This could cause the switch to rotate out of position and NOT make further contact with the parking lever to engage the parking brake switch and open the circuit.
- Replace parking brake pedal assembly if condition in step 2 is found. Refer to the repair manual for "Parking Brake Control Pedal Assembly: Check" procedures.
TSB BR002-07: Brake actuator noise
Fits: 2004 – 2007 PriusSome 2004-2007 Prius vehicles may make a screeching noise when you press or release the brake pedal. This noise can only be audible when the vehicle is in "READY" mode and the vehicle is not moving. Brake system performance is not affected by this noise. Use the following procedure to fix this issue.
- Confirm the noise condition by pressing/releasing the brake pedal.
- Bleed the brake system using a sweep tool and the correct repair procedure. If the noise is no longer present when pressing/releasing the brake pedal, the repair is complete. If noise is still present, go to step 3.
- If noise persists, replace brake actuator assembly.
Consult your repair information source for the correct procedure.
4. Road test to verify correct operation.