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Brakes

Brake Job: 2011-2015 Chevy Volt

At the wheels, the Chevy Volt is nothing more than a Chevy Cruz. But the similarities end under the hood at the master cylinder. These changes make all the difference if you are changing the brake pads.

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I know you are probably thinking: “There aren’t that many electric or hybrid vehicles on the roads. Why should I worry about the Chevy Volt?” 

The answer is because this is one of the vehicles that will cause you problems if you treat it like any other vehicle.

Pads & Rotors

There is nothing special about pad and rotor replacement on the Volt. The only precaution is to make sure the High-Pressure Accumulator (HPA) is depleted.

To deplete the HPA, the transmission must be in the PARK position, the power button in the OFF position, and the brakes not applied to ensure HPA pressure relief occurs. This process will take approximately 1 to 3 minutes.

The HPA can also be depleted with the ignition OFF and the brakes cool. Apply the brakes 3-5 times, or until the brake pedal effort increases significantly, in order to deplete the brake booster power reserve.

Thanks to regenerative braking, the brake pads and rotors will last a long time. This is why it is critical to use a high-quality brake pad. It the rear brakes are dragging or making noise, check the condition of the emergency/parking brake in the hat of the rotor. If there is pitting from rusting, the rotor must be replaced. Do not attempt to machine the surfaces.

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Brake Bleeding

The system can be bled manually or with a scan tool to bleed the HCU and master cylinder.

BLEEDING SEQUENCE:

1. Left front

2. Right front

3. Left rear

4. Right rear

Brake Pedal Feel Simulator

For the regenerative braking to work, the pressure applied to the brake pedal is measured by the system to generate braking force with the generator and charge the batteries. The system tricks the driver into thinking they are applying conventional hydraulic brakes.

On the pedal is a travel sensor, as well as a pressure sensor to measure force. To allow operation of the pedal feel simulator, the brake modulator assembly energizes and then closes the Normally Open (NO) valve to direct brake fluid only to the pedal feel simulator. The brake modulator also energizes and opens a Normally Closed (NC) valve to allow brake fluid to escape from the backside of the brake pedal feel simulator to the master cylinder reservoir, allowing the simulator piston to move.

Parking Brake

Park brake application input force is received by activating the Electronic Parking Brake (EPB) switch signaling the EPB control module and transfers an evenly distributed force through the parking brake cables and equalizer to the parking brake application levers. The electric parking brake can be used to prevent roll back for vehicles with a manual transmission taking off on a hill; a situation where no roll back is desired.

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Tension can be fully released from the park brake cables to allow for service of the park brake system. The tension in the cable can be released with a scan tool or manually.

METHOD 1:

Turn the ignition switch to the ON/RUN position with the engine OFF.

Place the automatic transmission in PARK or manual transmission in NEUTRAL, as equipped.

Apply and hold the brake pedal. The brake pedal must remain applied throughout the park brake cable tension release process.

Press and hold down the electronic park brake (EPB) switch approximately five seconds.

Observe the PARK BRAKE lamp on the instrument cluster.

When the PARK BRAKE lamp flashes, release then immediately press and release the EPB switch. The parking brake cable tension is fully released.

Release the brake pedal. 

In the event you need to release the EPB and the battery is dead, the following procedure may be used to release the brakes:

Remove the left rear tire and wheel assembly.

Remove the left rear wheelhouse panel liner.

Remove the protective plug (1) from the EPB manual release.

Using an appropriate square-drive tool, rotate the mechanism clockwise until the tension is fully released from the parking brake cables. Up to 50 turns may be required until the parking brake cable tension is fully released.

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